Mens Rea and Methamphetamine: High Time for a Modern Doctrine Acknowledging the Neuroscience of Addiction
Mens Rea and Methamphetamine: High Time for a Modern Doctrine Acknowledging the Neuroscience of Addiction
Meredith Cusick 0 1
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1 Fordham University School of Law
Recommended Citation Meredith Cusick, Mens Rea and Methamphetamine: High Time for a Modern Doctrine Acknowledging the Neuroscience of Addiction, 85 Fordham L. Rev. 2417 (2017). Available at: http://ir.lawnet.fordham.edu/flr/vol85/iss5/20
MENS REA AND METHAMPHETAMINE:
HIGH TIME FOR A MODERN DOCTRINE
ACKNOWLEDGING THE NEUROSCIENCE
In American criminal law, actus non facit reum, nisi mens sit rea, “an act
does not make one guilty, without a guilty mind.” Both actus reus and
mens rea are required to justify criminal liability. The Model Penal Code’s
(MPC) section on culpability has been especially influential on mens rea
analysis. An issue of increasing importance in this realm arises when an
offensive act is committed while the actor is under the influence of drugs.
Several legal doctrines address the effect of intoxication on mental state, including the MPC, limiting or eliminating its relevance to the mens rea analysis. Yet these doctrines do not differentiate between intoxication and addiction.
Neuroscience research reveals that drug addiction results in catastrophic
damage to the brain resulting in cognitive and behavioral deficits.
Methamphetamine addiction is of particular interest to criminal law
because it causes extensive neural destruction and is associated with
impulsive behavior, violent crime, and psychosis. Furthermore, research
has revealed important distinctions between the effects of acute intoxication
and addiction. These findings have implications for the broader doctrine of
mens rea and, specifically, the intoxication doctrines. This Note argues for
the adoption of an addiction doctrine that acknowledges the effect of
addiction on mens rea that is distinct from doctrines of intoxication.
I. MENS REA, THE MODEL PENAL CODE, AND THE COURTS UNDER
THE INFLUENCE OF INTOXICATION .............................................. 2420
* J.D. Candidate, 2018, Fordham University School of Law; M.S., 2014, Georgetown
University; B.S., 2012, University of Rochester. I would like to thank Professor Deborah
Denno for her guidance, insight, and enthusiasm throughout this process. I would also like
to thank my husband Louis and my family for their love and support.
III. THE MENS REA PROBLEM FOR DRUG-ADDICTED CRIMINAL
DEFENDANTS: DIFFERENTIATING ADDICTION FROM CRIMINAL
LAW’S INTOXICATION DOCTRINES .............................................. 2434
On a cold February day in Northern California, new mother Samantha
Green swam across a fifty-five-degree muddy slough while holding her
nineteen-day-old son, who was only wearing a thin onesie.1 After crossing
the water with her newborn, Green passed out under a tree.2 When she
awoke along the marsh the next day, she screamed until she was found.3
Her infant son had died of exposure to the cold.4 When police arrived, their
dashboard cameras captured Green shivering and howling at the death of
her son.5 She moaned in grief on the recording, crying out, “I just want my
baby,” “he doesn’t deserve this,” and “I love my baby. Why?”6
At trial, defense attorneys argued that, while Green was responsible for
her infant son’s death, she was not a murderer.7 Green, a
methamphetamine addict who had binged that tragic morning, crossed the
slough in search of the father of her child (her fiancé and drug provider)
correctly believing him to be with another woman.8 Defense experts
testified that Green was in the grips of a methamphetamine-induced
psychosis, experiencing apocalyptic thoughts and hallucinations.9
Bypassing the lesser charge of involuntary manslaughter, the jury found
Green guilty of second-degree murder10 by concluding that Green satisfied
the offense’s mental state requirements: “that 1) she intentionally
committed an act that she knew was dangerous to human life, and 2) had a
conscious disregard of that risk.”11 The jury was instructed that voluntary
intoxication was no defense to murder.12 Green was sentenced to fifteen
years to life in prison for her role in the death of her nineteen-day-old son
In American criminal law, “‘actus non facit reum, nisi mens sit rea’
(meaning ‘an act does not make one guilty, without a guilty mind’).”14
Both an act, actus reus, and a guilty mind, mens rea, are required for
criminal liability.15 The necessity of examining each defendant’s mindset
has contributed to the increasing overlap between neuroscience and
criminal law.16 Between 2006 and 2012, the number of “law and
neuroscience” publications multiplied by nearly tenfold, and interest in the
intersection between these two fields continues to grow.17 Of interest is the
potential for neuroscience to inform the understanding of moral
responsibility and criminal liability.18
This Note contributes to that body of scholarship by examining criminal
law’s approach to the relationship between drug use and mental state. It
examines neuroscience research on the effect of addiction on the brain, with
a focus on methamphetamine addiction, and considers whether these
findings suggest addiction requires a different legal doctrine than that of
The history of the intoxication doctrine reflects tensions between
criminal law, blameworthiness, and morality.19 What is not clear is
whether addiction should fit within the various intoxication doctrines—and,
if so, where—and how criminal law should adjust the mens rea analysis to
acknowledge neuroscience findings that drug addiction results in
catastrophic damage to the brain.20 This Note addresses this question with
a focus on the mens rea and intoxication provisions of the Modern Penal
Part I of this Note provides an overview of mens rea and the intoxication
doctrine, including an analysis of the three prominent doctrines of
intoxication in American criminal law. Next, Part II analyzes
methamphetamine abuse and the neurological and behavioral changes
associated with methamphetamine addiction. Then, Part III explores
difficulties in applying doctrines of intoxication to
methamphetamineaddicted individuals. Finally, Part IV makes the case for a separate doctrine
of addiction within the MPC and highlights addiction’s relevance to the
mens rea analysis.
I. MENS REA, THE MODEL PENAL CODE, AND THE COURTS
UNDER THE INFLUENCE OF INTOXICATION
The foundation of American criminal law relies on the positive
association between criminal liability and a guilty mind.21 But when an
actor has committed a crime while under the influence of a mind-altering
substance, there is debate as to whether intoxication should affect the mens
rea analysis and, therefore, the imposition of criminal liability.
This part examines the MPC’s approach to the mens rea analysis and the
legal doctrines of intoxication. Part I.A focuses on the MPC’s goals of
(last visited Mar. 25, 2017)
17. See Owen D. Jones et al., Neuroscientists in Court, 14 NATURE REVIEWS
NEUROSCIENCE 730, 731 (2013) (showing a sharp rise in “neurolaw” field publications in
18. See Bennett, supra note 14, at 437.
19. See infra Part I.B.
20. This Note does not take a position on the general admissibility of neuroscience
evidence in court for culpability analyses.
21. See infra Part I.A.
simplicity and standardization in adopting the four mental states of purpose,
knowledge, recklessness, and negligence. Part I.B discusses the emergence
of criminal law’s intoxication doctrines, which are often invoked to negate
A. Mens Rea in the Model Penal Code
The MPC, completed in 1962 by the American Law Institute (ALI),
sought to bring clarity to criminal common law.22 Its promulgation
“prompted a wave of state code reforms in the 1960s and 1970s, each
influenced by the Model Penal Code,” and the MPC is perhaps “the closest
thing to being an American criminal code.”23 In addition to its influence on
state code reform, the MPC is frequently cited by courts as persuasive
authority.24 The MPC’s commentaries, published in the 1980s, illuminate
the reasoning behind code provisions and frequently discuss the adoption or
rejection of individual provisions by the states.25 The MPC’s mens rea
section, section 2.02, is perhaps its greatest contribution to American
criminal law reform.26
The drafters of the MPC faced a daunting task in grappling with and
codifying the near eighty mens rea terms in use among the states.27 The
MPC predominantly sought to simplify and standardize the mens rea
analysis in two ways: (1) by reducing the use of normative terms and (2) by
decreasing the number of mental states.28
Abandoning terminology that required normative judgments—such as
malice aforethought, premeditation, willfulness, carelessness, and
wantonness—the drafters sought standardization in adopting “presumably
testable phenomena such as ‘conscious object’ or ‘knowledge.’”29 The
commonly held belief that consciousness and voluntariness would involve a
more scientific analysis highlights the substantial influence exerted by the
contemporaneous science of Freudian psychoanalysis.30 The MPC treats
the conscious, voluntary act as a threshold requirement before a defendant’s
mens rea can be determined.31 The mens rea analysis that proceeded was
then meant to “represent a subjective inquiry into a defendant’s mental
attitude, not an objective inquiry based upon a reasonable person
standard.”32 The emphasis on subjectivity also reflects the Freudian
approach to individualized therapy.33 The drafters incorporated the science
of their times while developing the MPC.34 While the fields of
neuroscience and psychology have changed drastically since Freud’s time,
the MPC’s mens rea analysis has not. Still of critical importance to
criminal law is the MPC’s most radical change to the law of mens rea,
which was the adoption of only four culpability terms: purpose,
knowledge, recklessness, and negligence.35
The selection of only four mens rea terms may have been necessary to
accommodate the MPC’s novel requirement that each element of an offense
carry its own mental state.36 Instead of a typical offense analysis, in which
only one state of mind is required by an offense, the MPC adopted criminal
offense definitions that contain multiple elements, each of which might
require a different culpable mental state.37 The elements to be examined
under the MPC are conduct, attendant circumstance, and result.38
By establishing only four culpability terms, the MPC eliminated some of
the flexibility and nuance associated with the traditional mens rea analysis.
Throughout history, “the process of recognizing additional distinctions [in
culpable states of mind] has been through the recognition of additional
bases for mitigation. The new distinction creates a new category that will
receive less harsh punishment, or limits a more harsh punishment to the old
category.”39 The restriction of culpable mental states has resulted in the
formation of doctrines seeking to negate mens rea, such as intoxication,
which play a significant role in American criminal law.
B. The Law on Drugs
The MPC and common law differ in their approach to the culpability of
an intoxicated criminal defendant. This section highlights the three
prominent doctrines of intoxication in American criminal law: (1) MPC
section 2.08, (2) the common law doctrine of specific intent, and (3) the
Supreme Court’s ruling in Montana v. Egelhoff.40
1. The MPC on Drugs: Voluntary Intoxication
The MPC addresses drug use in section 2.08, titled “Intoxication.”41
Although often referred to as a defense or excuse, the MPC’s doctrine of
intoxication is nearly the opposite.42 First, even when intoxication is
applicable, it is not so much a defense as the absence of an offense, or the
failure to establish proof of mens rea.43 Second, the MPC contracts
intoxication’s scope as a defense by articulating “what amounts to an
intoxication exception to the general rule that criminal liability requires a
match between behavior and offense definition.”44 Intoxication is generally
not an excuse for criminal conduct under the MPC45 because it cannot be
used to negate recklessness46 and “recklessness is sufficient to establish
mens rea for most offenses.”47
Reflecting the views at the time it was adopted, the MPC’s intoxication
section deals almost exclusively with intoxication due to alcohol.
Throughout the Comments, drunkenness is frequently substituted for
intoxication.48 But in the last portion of the Comments, the definition of
“intoxication” is untethered from alcohol intoxication: “The use of drugs or
any other substance is to be treated in the same way as the use of
alcohol.”49 A short statement about narcotics is all that follows as the
Comment explains that the intoxication doctrine will have little practical
bearing on crimes committed under the influence of narcotics, as “[t]he
effect of a narcotic is to make the addict less aggressive without any great
interference with mental powers.”50
Although devoting little space to drugs other than alcohol, the Comments
discuss at length how the MPC’s intoxication doctrine (allowing negation
of purpose and knowledge) is clearer than—yet substantively equal to—the
common law’s approach.51
2. The Common Law on Drugs:
Specific Intent Negation
Prior to the nineteenth century, the common law did not allow any
concession for intoxication in determining criminal liability.52 Due to the
harsh effects of this standard, judges sought a workable compromise by
which they might consider intoxication without undermining the entirety of
the traditional mens rea analysis.53 Judge John Coleridge articulated this
compromise in 1849 in noting that “evidence of voluntary intoxication was
relevant only if it deprived the defendant of ‘the power of forming any
specific intention.’”54 From here, the distinction between general and
specific intent offenses originated, providing the basis for the intoxication
doctrines followed by many states and courts.
The distinction between general and specific intent “is a device,
conceived at common law, to achieve a certain result rather than reflecting a
coherent theory.”55 As a result, it is not possible to accurately frame
general and specific intent within a complete, unitary theory.56 The most
simple formulation is this: specific-intent offenses are those that require
proof that the defendant intended to bring about some additional
consequence or social harm.57 The new common law rule allows negation
of specific intent, but not general intent, offenses.58
The ambiguous and “perhaps incoherent” specific intent doctrine
developed in response to the harshness of a rule that prohibited
consideration of intoxication in the mens rea analysis.59 The common law
formulation is substantively equivalent to the Model Penal Code’s
intoxication doctrine because crimes of recklessness and negligence are
usually considered general intent offenses.60 Just as intoxication does not
negate a general intent offense under the common law, it does not negate
recklessness or negligence under the MPC, whatever the effect the
intoxication may have had on the awareness or knowledge of the actor.61
At the heart of both doctrines is an attempt to acknowledge the potential for
intoxication to alter one’s mens rea or mental culpability.
3. The Supreme Court on Drugs:
Montana v. Egelhoff
The leading U.S. Supreme Court case on voluntary intoxication,
Montana v. Egelhoff,62 embodies a decidedly different approach. In this
case, a divided Court upheld a state law prohibiting consideration of
voluntary intoxication in the determination of mens rea.63 The Court
determined that such a law does not violate the Due Process Clause of the
Constitution, because the new common law rule—that intoxication may be
considered for intent—is not “so rooted in the traditions and conscience of
our people as to be ranked as fundamental.”64 The Egelhoff decision
revealed a Court fragmented over whether states may bar consideration of
voluntary intoxication.65 With only a plurality decision, the narrow
grounds on which Justice Ginsburg concurred established the holding of the
Court.66 As discussed in Tidwell v. Cash,67 the Court “clearly established
that when a state law barring consideration of voluntary intoxication can be
characterized as a rule ‘[d]efining mens rea to eliminate the exculpatory
value of voluntary intoxication,’ rather than as a rule of evidence, the statute
does not offend the Due Process Clause.”68 In light of this ruling, a state
does not have to prove purpose or knowledge in “a purely subjective sense”
but may prove “circumstances that would otherwise establish knowledge or
purpose ‘but for’ [the defendant’s] voluntary intoxication.”69 Thus, a
defendant’s voluntary intoxication may be irrelevant to the mens rea
common law and MPC formulations are generally the same); Johnson, supra note 52, at
532–38 (stating that “[c]rimes of recklessness and negligence are general-intent offenses”).
61. See MODEL PENAL CODE § 2.08(2), at 349.
62. 518 U.S. 37 (1996).
63. See id. at 56.
64. See id. at 47–48; see also U.S. CONST. amend. V (“No person shall . . . be deprived
of life, liberty, or property, without due process of law.”); id. amend. XIV, § 1 (“[N]or shall
any State deprive any person of life, liberty, or property, without due process of law.”).
65. See Egelhoff, 518 U.S. at 37.
66. See, e.g., Marks v. United States, 430 U.S. 188, 193 (1977) (“When a fragmented
Court decides a case and no single rationale explaining the result enjoys the assent of five
Justices, ‘the holding of the Court may be viewed as that position taken by those Members
who concurred in the judgments on the narrowest grounds.’” (quoting Gregg v. Georgia, 428
U.S. 153, 169 n.15 (1976))).
67. No. EDCV 10-1883-AG RCF, 2012 WL 1570038 (C.D. Cal. Mar. 29, 2012), report
and recommendation adopted, No. EDCV 10-1883-AG RCF, 2012 WL 1570032 (C.D. Cal.
Apr. 30, 2012).
68. Id. at *10 (alteration in original) (quoting Egelhoff, 518 U.S. at 58–59 (Ginsburg, J.,
69. Egelhoff, 518 U.S. at 58 (Ginsburg, J. concurring).
70. See id.
The Court’s approach differs significantly from both the MPC’s
intoxication doctrine71 and the specific-intent common law doctrine, which
had been adopted by a majority of states before Egelhoff.72 While the MPC
and common law doctrines of intoxication may limit the consideration of
voluntary intoxication in the mens rea analysis, neither doctrine allows its
After Egelhoff, there is no clear prevailing doctrine among the states.74
The diversity in approaches to the relationship between intoxication and
mens rea, as emphasized by Justice Antonin Scalia in Egelhoff, reflects
tensions between criminal law and virtues.75 The doctrine of mens rea
“historically provided the tools for a constantly shifting adjustment of the
tension between the evolving aims of criminal law and changing religious,
moral, philosophical, and medical views of the nature of man.”76 Evolved
understanding of the differences between intoxication and addiction—in
particular, neuroscience findings that drug addiction results in catastrophic
damage to the brain—may suggest such an adjustment for the mens rea
analysis for drug-addicted criminal defendants.
II. METHAMPHETAMINE ADDICTION AND THE BRAIN
Methamphetamine is a particularly addictive stimulant, abuse of which is
associated with significant neurological damage and severe effects on
cognitive and behavioral functioning.77 Popular use of methamphetamine
has increased substantially in the last twenty years, in part due to the
simplicity of producing the drug.78 In contrast to cocaine, which is derived
naturally in Central and South America and then processed elsewhere,
methamphetamine can be manufactured on a large scale in the United
States.79 The 2004 determination that methamphetamine was “the
fastestgrowing illicit drug in North America”80 prompted Congress to pass the
amphetamine Epidemic Act of 2005
.81 This act initially
decreased methamphetamine availability by limiting access to its precursor
chemicals, but production and use has been on the rise since 2011.82
This part focuses on methamphetamine as a model drug through which to
examine the relationship between drug addiction and mental states
implicated in the mens rea analysis.83 Part II.A explains why this Note
focuses on methamphetamine addiction, and Part II.B discusses the unique
pattern of methamphetamine use and abuse, which illuminates the dramatic
effect this addiction has on an individual’s life. Part II.C then examines
some of the significant neurophysiological changes associated with
methamphetamine addiction and the correlative influence on behavior and
A. Why Focus on Methamphetamine?
Methamphetamine tests the boundaries of criminal law because it can
feature prominently in crimes unrelated to possession, use, and
trafficking.84 Although the use of heroin, a narcotic, has skyrocketed in
America,85 any amount of methamphetamine abuse remains critically
important to the criminal justice system because its abuse drives violent
crime.86 Where its abuse is prevalent, this stimulant’s relationship to
79. See Arthur K. Cho, Ice: A New Dosage Form of an Old Drug, 249 SCIENCE 631,
633 (1990). Methamphetamine can be manufactured in a simple one-step process, in which
either ephedrine or pseudophedrine is reduced. See id. This method creates what is known
colloquially as “crystal” or “ice,” due to the drug’s heightened purity as compared to the
market’s previous methamphetamine. See id. Prior to the emergence of “crystal meth,”
synthesis was more commonly achieved through a condensation reaction between
phenylacetone and methylamine, which resulted in a higher proportion of contaminants. See
murders and armed robberies has been described as “truly frightening,”
appearing to lead to “utterly irrational violence.”87
Methamphetamine is a highly potent and addictive psychostimulant but is
unique even among stimulants.88 It is easily manufactured with modest
equipment and knowledge and is thus more widely available than most
drugs.89 While cocaine predominantly affects one biological pathway,90
methamphetamine “exerts multiple pharmacological effects via different
molecular processes.”91 In addition, because methamphetamine’s
elimination half-life is substantially longer than cocaine’s,
methamphetamine exerts behavioral and psychological effects for
significantly longer periods of time.92 In comparison to its parent
compound, amphetamine, methamphetamine is lipophilic, which allows it
to better penetrate the central nervous system.93 These characteristics have
made the effects of methamphetamine abuse an area of focused study in
several scientific fields.94
Methamphetamine-addicted individuals are in prisons and on death row
for committing crimes unrelated to drug possession, distribution, or
manufacturing.95 In prosecuting these offenses, the state has the burden of
proving that the defendant satisfies the required mens rea for each element
of the offenses with which he has been charged.96 Thus, it is necessary to
inquire whether these defendants’ methamphetamine addiction has any
significance within the mens rea analysis. As the mens rea analysis requires
a subjective determination of mental state, the effects of methamphetamine
on the addicted user must first be examined for their potential to influence
B. The High, Binge, Tweak, and Crash:
An Introduction to Methamphetamine Use and Abuse
Methamphetamine addicts’ distinctive pattern of drug use highlights the
drug’s dramatic effect on individual’s lives and informs a
methamphetamine user’s experience over the course of four stages: the
high, the binge, the tweak, and the crash.97
When methamphetamine first enters the body, the person experiences
“the high,” which is characterized by an immediate rush of pleasure lasting
for a matter of minutes, “followed by a euphoria that lasts for up to 12
hours.”98 During the high, the user may experience heightened confidence,
assertiveness, productivity, energy, attentiveness, and curiosity, but he may
also experience increased aggression, anxiety, and insomnia.99 As the high
fades, most users will continue to consume methamphetamine every few
hours to maintain feelings of euphoria in “the binge” period. A typical user
may dose between one and six times a day, but with each dose of
methamphetamine, there is less of a rush in response until, eventually, there
is no rush at all.100 Users will typically self-administer methamphetamine
until they either run out of the drug or choose to stop dosing, usually due to
the lack of a rush as a result of tolerance.101 Users may not eat or sleep at
all during the binge, which can last from three to fifteen days.102
It is the detrimental physical effects of “the tweak” that most people
associate with methamphetamine use and abuse.103 In this stage, high
adrenaline causes the user to engage in obsessive behavior.104 The user
may experience formication—the unnerving feeling that bugs are crawling
under the skin—which “causes the user to pick out skin until sores and cuts,
known as ‘crank bugs,’ arise. The user can also become physically
aggressive, while simultaneously experiencing a psychosis that is
characterized by a deluded and paranoid thought process.”105 The last stage
of methamphetamine use is “the crash,” a period of extreme somnolence in
which the user may sleep for up to three days.106
Repeatedly subjecting the body and brain to this pattern of drug use
results in catastrophic damage to bodily systems. Recent neuroscience
research has focused on key brain areas damaged by methamphetamine
abuse and associated changes in cognition and behavior.
C. Your Brain on Methamphetamine: Neurophysiological Changes and Associated Cognitive and Behavioral Deficits
Neurophysiological research has revealed that methamphetamine
addiction causes global neural impairment, with catastrophic damage to key
neural structures and deficits in associated cognition and behaviors.107 This
section discusses one of the severe effects of methamphetamine addiction—
damage to a critical neurotransmitter system—and resultant neurocognitive
and behavioral deficits.
1. Methamphetamine Addiction Causes Severe Damage
to the Critical Dopaminergic System
Long-term methamphetamine abuse leads to catastrophic brain changes
that are due, in part, to the drug’s neurotoxicity.108 Methamphetamine has
severe neurotoxic effects on neurotransmitter systems, particularly
dopamine circuits109—which predominate in the striatum of the brain110—
and serotonin circuits in the frontal cortex and hippocampus.111 There are
several pathways by which methamphetamine might exert its neurotoxic
effects.112 Much of the scientific literature focuses on dopamine pathways
because methamphetamine’s ability to regulate dopamine transmission
through multiple mechanisms contributes to the drug’s effects as a general
Methamphetamine causes an initial surge in dopamine levels,114 resulting
in the pleasurable effects of the methamphetamine high. It accomplishes
this, in part, by acting as a substrate115 for the dopamine transporter, which
increases extracellular, or active, dopamine levels116 and increasing the
excitability of dopaminergic neurons.117 In response to this dopamine
surge, the brain circuitry compensates by decreasing dopamine
transmission.118 The combined effects of long-term dopamine
overexposure and methamphetamine neurotoxicity result in catastrophic
degeneration of dopaminergic nerve terminals and depletion of dopamine in
the central nervous system.119 Similar effects are seen on serotonergic
Key brain areas that are impaired by methamphetamine addiction include
the striatum, amygdala, and prefrontal cortex, as these areas rely on
dopaminergic and serotonergic pathways.121 The impairment of the
functioning of dopaminergic-dense and serotonergic-dense structures in the
brain, which is just one of the many neurophysiological effects of
methamphetamine addiction, has associated neurological, social-cognitive,
and behavioral deficits.122
2. Methamphetamine Addiction:
Emotion Dysregulation, Aggression, Impulsivity, and Psychosis
The neurological damage caused by methamphetamine addiction is
associated with social-cognitive impairments, such as emotion
dysregulation, and associated maladaptive behaviors, including impulsivity,
aggression, and even psychosis. Emotion dysregulation is the suboptimal
modulation of operations that influence responses during emotion
processing, particularly in response to provocation.123 Emotional regulation
is a primary function of the amygdala, which is rich in D2-type dopamine
receptors,124 and the prefrontal cortex, which contributes to response
inhibition and contains both dopaminergic and serotonergic pathways.125
Emotion regulation is also influenced by activity in the striatum—rich in
D2/D3-type dopamine receptors—which is implicated in controlling
delayed gratification and impulsivity.126 Increased severity of addiction is
correlated with increased emotional dysregulation and associated behavioral
Emotion dysregulation is associated with impulsivity and increased
propensity for aggression and violence.128 Dopamine influences
impulsivity, “a category of behaviors encompassing deficits in the ability to
delay immediate gratification for future larger rewards, and in response
inhibition.”129 The loss of striatal dopamine activity in methamphetamine
abusers contributes to the high impulsivity and lack of inhibition control
observed in these individuals.130 In addition, the striatal dopamine system
is crucial to processing probabilistic information.131 Therefore,
methamphetamine-addicted individuals do not process or learn from the
probability of risk in the same way as nonaddicted individuals.132 This lack
of inhibition and failure to perceive risk is associated with increased
aggression and violence133 but is not the sole factor behind these behaviors.
Aggression and violence are associated with disturbances in emotional
regulation, response inhibition, facial affect recognition, self-awareness,
and theory of mind, all of which have been demonstrated in
methamphetamine-dependent individuals.134 Methamphetamine addicts
themselves perceive the drug as contributing to their violence, specifically
attributing this to the drug decreasing their ability to empathize and its
tendency to dominate every aspect of their life.135 Neurobiologically,
aggression is associated with defects in the emotion-processing circuitry
between the amygdala and prefrontal cortex.136 Methamphetamine addicts
show severe structural, neurochemical, and metabolic abnormalities in this
circuitry.137 Scientific models of aggression suggest that aggression is
increased where there is failure of either emotional regulation or emotional
insight.138 Methamphetamine addiction impairs both these processes,
which contributes to methamphetamine addicts’ aggression, as they may
misinterpret stimuli as hostile and threatening.139
The effects of methamphetamine addiction can become so severe as to
result in methamphetamine-induced psychosis. Acute methamphetamine
intoxication may have transient psychosis-inducing effects that are “almost
indistinguishable from acute paranoid schizophrenia,” including
hallucinations and delusions.140 The high drug doses associated with
140. Rebecca McKetin et al., The Profile of Psychiatric Symptoms Exacerbated by
Methamphetamine Use, 161 DRUG & ALCOHOL DEPENDENCE 104, 104 (2016). This study
sought to differentiate psychiatric symptoms induced by methamphetamine use from those
caused by preexisting psychiatric disorders. See id. at 105. Methamphetamine use did not
induce the negative symptoms associated with schizophrenia—diminished emotional
expression or avolition—but did increase the severity of many psychiatric symptoms,
including positive psychotic symptoms (hallucinations and persecutory delusions), affective
symptoms (depression, suicidality, hostility, and self-neglect), and psychomotor agitation.
See id. at 107–08.
addiction may result in an enduring psychosis that persists even after the
drug has been eliminated from the bloodstream.141 Even individuals who
recover from the prolonged psychosis may suffer “flashbacks” of psychotic
symptoms when confronted with stressful situations.142
Methamphetamineinduced psychosis is often cited by experts testifying on behalf of violent
methamphetamine-addicted criminal defendants.143
Methamphetamine addiction results in catastrophic brain damage to
critical neural circuits and structures. Associated with this damage are
corresponding cognitive and behavioral deficits linked to long-term
methamphetamine addiction, which are distinct from effects due to acute
intoxication. This may suggest that addiction, particularly to
methamphetamine, should be handled in a different manner than
intoxication in the mens rea analysis.
III. THE MENS REA PROBLEM FOR DRUG-ADDICTED
CRIMINAL DEFENDANTS: DIFFERENTIATING ADDICTION
FROM CRIMINAL LAW’S INTOXICATION DOCTRINES
American criminal law has various approaches to the effect of
intoxication on mens rea, including a Supreme Court ruling from over
twenty years ago that allows states to prohibit consideration of intoxication
in the mens rea analysis.144 But if methamphetamine addiction results in
dramatic brain changes, as supported by the neuroscience findings
discussed above, should its effect on mental culpability be considered in the
mens rea analysis in a different way than acute intoxication?
This part discusses the arguments for and against differentiating between
acute intoxication and addiction. Part III.A looks at whether addiction
should be considered “voluntary” and thus subject to the same doctrines
that govern voluntary intoxication. Part III.B discusses whether addiction
affects mental state and, if so, whether disallowing consideration of
addiction in the mens rea analysis improperly elevates actus reus and
violates due process. Then, Part III.C addresses whether pragmatic
concerns about juries’ ability to make fine culpability distinctions support
rejection of neuroscience in the courtroom.
A. The Nuances of Voluntary Addiction
The legal doctrines of intoxication represent an exception to the general
tenet of criminal law that liability requires a match between behavior and
141. See Barr et al., supra note 78, at 306.
142. See id.
143. See, e.g., Bonnifield v. Lewis, No. C 12-3857 PJH (PR), 2014 WL 1101658, at *4–5
(N.D. Cal. Mar. 18, 2014)
(describing expert testimony that the defendant had “damaged
himself irretrievably due to decades of methamphetamine abuse” and was experiencing a
“drug-induced psychosis,” which lasted even when the drug had exited his system); Malone
v. Oklahoma, 168 P.3d 185, 195 (Okla. Crim. App. 2007) (recounting the testimony of Dr.
David Smith, who stated that the effect on a person of “amphetamine psychosis” is
comparable to paranoid schizophrenia).
144. See generally Montana v. Egelhoff, 518 U.S. 37 (1996); supra Part I.B.
offense mental state requirements.145 Under Egelhoff, the state does not
have to prove mens rea in “a purely subjective sense,” but it may instead
prove circumstances that would otherwise establish the required mens rea
“but for” the intoxication.146 The question is whether this exception should
extend to addiction, thus encompassing addiction within the doctrines of
intoxication. Is addiction as voluntary as intoxication?
Limiting the legal relevance of intoxication to the mens rea analysis is
generally justified by voluntariness: an individual should not be found less
blameworthy for conduct committed while in a voluntarily induced
intoxicated state.147 “The law accepts free will and blame-worthiness as a
general premise,” and will rarely depart from that presumption.148 The
legal exception to this tenet, regarding issues of capacity, arises where the
defendant’s incapacitated state is seemingly out of his control and cannot be
deterred.149 By contrast, imbibing intoxicating substances is considered a
choice and gross intoxication a moral failing.150
Deterrence is a clear goal of doctrines that limit or eliminate the
relevance of voluntary intoxication to the mens rea analysis. The MPC
Comments acknowledge that, even if intoxication does affect an
individual’s awareness of risk, “[b]ecoming so drunk as to destroy
temporarily the actor’s powers of perception and judgment is conduct that
plainly has no affirmative social value . . . . The actor’s moral culpability
lies in engaging in such conduct.”151 In the Egelhoff plurality opinion,
Justice Scalia emphasized that a rule disallowing consideration of voluntary
intoxication acts as a general deterrent, a specific deterrent (in the form of
incarceration), and “comports with and implements society’s moral
perception that one who has voluntarily impaired his own faculties should
be responsible for the consequences.”152
The issues of deterrence and voluntariness, however, may require a
distinction between acute intoxication and addiction. The deterrent effects
of intoxication doctrines may not apply to addiction due to the disconnect
between the act of drug use and the resultant condition of addiction.153
Only some individuals who experiment with drugs become addicted.154
Contrast this with intoxication, where the ingestion of intoxicating
substances is directly and temporally related to the inducement of an
intoxicated state.155 Because of this causal connection, doctrines seeking to
deter offenses committed while intoxicated can effectively deter the act of
becoming intoxicated.156 But the same is not true for addiction.157 This
difference in causality suggests that deterrence is not a likely outcome of
addressing addiction under current doctrines of intoxication.
Furthermore, neuroscience findings posit that neither the initiation nor
maintenance of addiction is voluntary in the same way as is the act of
ingesting a substance to become acutely intoxicated.158 Drug-addicted
individuals and nonaddicted individuals may seek drugs for vastly different
reasons: while a nonaddicted individual may seek the “high” or
stressrelieving effects of the drug, an addict is fulfilling a need.159 As one former
addict recounted, “While actively using, I don’t care about you, I don’t care
about myself, and I sure as hell don’t care about no police. . . . I was using
against my will because once you’re in that lifestyle, it totally consumes
you. We don’t even think about the consequences.”160 While doctrines of
intoxication might fairly impute a mental state for voluntarily choosing to
become intoxicated, the justification for doing so does not apply to
The emergence of drug addiction in an individual “is ultimately a
function of interactions between drug effects, biological and environmental
factors, which are crucially influenced by the developmental stage of the
individual.”161 The development of addiction is in part mediated by the
dopaminergic system which, as discussed above, is catastrophically altered
by methamphetamine use.162 “Repeated use of the drug changes the brain
of the user so that behaviors become more reflexive and, consequently,
much less amenable to cognitive interference.”163 The entire system of
processing risk and reward becomes compromised.164 Acute drug intake
increases dopamine release, which is followed by marked decreases in
154. See id.
155. See Jordan B. Peterson et al., Acute Alcohol Intoxication and Cognitive Functioning,
51 J. STUD. ON ALCOHOL 114, 115–16 (1990) (describing methods of measuring alcohol
intoxication, performed fifteen minutes after drinking).
156. See Egelhoff, 518 U.S. at 49–50 (stating that the effect of increased punishment for
unlawful acts committed while drunk has the direct result of deterring drunkenness).
157. See Baler & Volkow, supra note 153, at 559.
158. See id.
159. See id. at 560 (noting that addicted individuals continue to take drugs compulsively
“even when it is no longer perceived as pleasurable”).
160. Juleyka Lantigua-Williams, ‘Using Against My Will,’ ATLANTIC (June 19, 2016),
(providing an edited portion of a conversation between the author and Adrian Silva, a former
methamphetamine addict with an extensive criminal past, who reformed his ways after
participating in a court’s drug program) [https://perma.cc/23QH-4GYJ].
161. Baler & Volkow, supra note 153, at 559.
162. See supra Part II.C.
163. Baler & Volkow, supra note 153, at 559.
164. See id. at 560.
drug-addicted individuals.165 This pattern of dopamine flux becomes
conditionally associated with other stimuli or cues, until the stimuli
themselves are able to stimulate dopamine release and a strong desire for
the drug.166 Even with knowledge of the negative effects of the drug, this
positive feedback loop makes an addict in remission extremely vulnerable
and at high risk of relapse when exposed to any number of previously
Furthermore, increased severity of addiction is associated with increased
severity of deficits in coping with stress.168 Deficits in coping with stress
are strongly related to drug craving, and the involvement of several
neurotransmitter systems in that relationship has been shown not only for
users of methamphetamine but also for those who use cocaine, heroin,
alcohol, and tobacco.169 The emotion dysregulation associated with drug
abuse contributes to the maintenance of addiction, which in turn contributes
to increased severity of dysregulation.170 This positive feedback loop
makes recovery from addiction incredibly difficult—and relapse likely171—
and highlights the differences between acute intoxication and the significant
neurological effects of long-term addiction. These effects suggest that
neither the initiation nor maintenance of addiction is voluntary and that
addiction is not a moral failing, but a biological one.
B. Does Addiction Affect Mens Rea?
Even if addiction is not voluntary, it has been argued that there is no
effect of addiction on mens rea. As it was described by one scholar:
[A]ddicts . . . will not lack mens rea for their substance-related criminal
activity . . . . In most cases of serious criminal wrongdoing . . . there still
will be no mens rea problem. An addict who burgles, robs, or kills surely
forms the intent to do so.172
The MPC agrees, stating that there is a “relative rarity of cases where
intoxication really does engender unawareness as distinguished from
imprudence.”173 Courts have employed similar reasoning when faced with
acts committed by methamphetamine-addicted individuals. In denying a
writ of habeas corpus for a man sentenced to death, a Texas court
determined that no reasonable juror would have found the man’s mental
impairments—including a chronic methamphetamine addiction and
thirteen-day methamphetamine binge—negated the intent or knowledge
165. See id.
166. See id.
167. See id.
168. See Okita et al., supra note 122, at 168.
169. See id.
170. See id.; see also Kohno et al., supra note 127, at 1554 (noting that methamphetamine
addiction’s effect on temporal discounting of rewards “may promote the initiation as well as
the maintenance of addiction”).
171. See Okita et al., supra note 122, at 168.
172. Morse, supra note 148, at 27.
173. MODEL PENAL CODE § 2.08 cmt. 1, at 359
(AM. LAW INST., Official Draft and
Revised Comments 1985)
required for a capital murder conviction.174 In granting a certificate of
appealability for ineffective assistance of counsel,175 a California court
found the prisoner had not made a substantial showing that trial counsel
was ineffective for failing to present the defense of mental defect due to
long-term drug abuse but had made a showing that counsel was ineffective
for failing to do the same for a mental defect due to causes other than
longterm drug use.176 The court was not convinced that a reasonable juror
would have ruled differently had counsel argued at the guilt phase of trial
that the defendant’s long-term methamphetamine addiction had caused
brain damage that prevented him from forming an intent to kill.177 This
distinction illuminates the court’s opinion that a reasonable juror would not
believe long-term methamphetamine addiction might cause a mental defect
that negates mens rea, even if said juror might believe that a mental defect
due to a different, non-drug-related cause can negate mens rea.178
The severe effects of methamphetamine addiction on the brain and
associated cognitive and behavioral deficits, however, suggest that
addiction does affect mens rea.179 The distinctions among the culpability
terms of the MPC and terms used in state and federal jurisdictions lie along
the axes of attitude and probability.180 For purposely and knowingly, the
distinction is one of attitude: conscious object versus awareness.181 The
Comments make this explicit, stating that “action is not
purposive . . . unless it was [the actor’s] conscious object to perform an
action of that nature or to cause such a result. It is meaningful to think of
the actor’s attitude as different.”182 In contrast, the distinction between
knowingly and recklessly is one of probability: practically certain versus
substantial risk.183 While both involve awareness of risk, recklessness
involves risk “of a probability less than substantial certainty” that is
“unjustifiable.”184 Finally, the distinction between recklessly and
negligently is one of awareness.185 While acting recklessly involves
“conscious risk creation,”186 a person acts negligently “when he
inadvertently creates a substantial and unjustifiable risk of which he ought
to be aware.”187 The question is whether methamphetamine addiction
influences the ability to form any of these mental states.
Methamphetamine addiction results in organic brain damage to key
pathways and structures that influence cognition and behavior, contributing
to emotion dysregulation, impulsivity, deficits in risk and reward
processing, and characteristics of psychosis.188 Each of these deficits may
influence an individual’s ability to form an offense’s requisite mens rea.
For intent, an impulsive individual, who struggles to inhibit his response to
provocation and misapprehends the world as a dangerous place,189 may not
have the “conscious object” to cause, for example, the death of another
human or may not be practically certain that such result will occur, as
required for knowledge.190 If the deficits are severe enough, such an
individual may not even satisfy the requirements of recklessness, because
he may not be capable of comprehending the existence of a risk.191 It is
only negligence, the objective culpability term, for which addiction can
categorically be stated to have no effect.192 Therefore, particularly
depending on the severity of the addiction, neuroscience research suggests
that methamphetamine addiction may have a significant effect on the ability
of a criminal defendant to form an offense’s requisite mental state.
Some have maligned the argument that addiction should be considered in
the mens rea analysis, even if it does influence mens rea,193 because drug
users are aware of the risk of addiction and can “fairly be held responsible
to a substantial degree for becoming addicted.”194 While the close temporal
relationship between ingesting an intoxicant and committing acts while
intoxicated might justify such liability under the legal doctrines of
intoxication,195 addiction is distinguished by the more tenuous connection
“substantial” and “unjustifiable” are terms of degree, so the MPC provides a standard for
determining “how substantial and how unjustifiable the risk must be in order to warrant a
finding of culpability.” Id. § 2.02 cmt. 3, at 237. The defendant’s disregard of the risk must
“involve a gross deviation from the standard of conduct that a law-abiding person would
observe in the actor’s situation.” Id. § 2.02 cmt. 3, at 226.
185. See Robinson, supra note 27, at 841.
186. MODEL PENAL CODE § 2.02 cmt. 3, at 236.
187. Id. § 2.02 cmt. 4, at 240.
188. See supra Part II.C.
189. See supra note 139 and accompanying text.
190. See supra notes 181–82 and accompanying text.
191. See supra note 132 and accompanying text.
192. See Susan F. Mandiberg, Protecting Society and Defendants Too: The
Constitutional Dilemma of Mental Abnormality and Intoxication Defenses, 53 FORDHAM L.
REV. 221, 228 (1984) (noting that “mental abnormality and intoxication can be negativing
defenses only to subjective mental state requirements: intent, purpose, knowledge, and in
some cases recklessness” (footnote omitted)).
193. See, e.g., Herbert Fingarette, Addiction and Criminal Responsibility, 84 YALE L.J.
413 (1975) (criticizing arguments that addiction-related conduct is involuntary); Morse,
supra note 148.
194. Morse, supra note 148, at 22.
195. See supra note 155 and accompanying text.
between the initial acts contributing to one’s status as an addict and acts
committed months, or even years, later.196 “Very few [individuals
becoming addicts] would in fact foresee committing specific
crimes . . . . [E]ven if addicts are mostly responsible for becoming addicted
and may be aware of the general risks addiction poses, this responsibility is
different from the responsibility necessary to be culpable for specific
crimes.”197 Therefore, imputing the mental state involved in becoming an
addict to the offense’s requisite mens rea is inappropriate. Neither the
“conduct” nor “moral culpability” of becoming addicted to drugs—as is
used to justify intoxication doctrines by the MPC and Egelhoff,
respectively198— justifies assigning liability regardless of mens rea to
drugaddicted criminal defendants.
In Egelhoff, the Court determined that excising voluntary intoxication
from the mens rea analysis—regardless of the actual effect of intoxication
on mental state—did not violate due process because the right to have
intoxication considered on issues of intent is not fundamental.199 However,
the requirement that criminal defendants satisfy offenses’ mens rea
requirements to be found guilty—and the intended subjectivity of that
analysis—may be so rooted in the conscience of the American people as to
be fundamental.200 The mens rea analysis examines the subjective mental
state of the criminal defendant.201 Excluding the negating evidence of
addiction on mental state selectively redefines an offense to allow the
defendant at issue to be found guilty on objective standards, while
subjective standards apply to everyone else.202 This creates a mere legal
fiction, as “[s]uch concealed redefinition [of the offense] permits the
illusion that the defendant was convicted on the basis of a subjective mental
state, and so permits the enhanced punishment attendant upon such
Furthermore, imputing the mens rea for becoming an addict to crimes
committed once addicted is a form of strict liability,204 as it assigns liability
for actus reus with no regard for mens rea.205 For at least 800 years,
criminal law has focused on both the criminal act and the criminal mind.206
In the American criminal justice system, mental state is as important an
element as the act itself in justifying criminal liability.207 Ignoring a
defendant’s addiction in the mens rea analysis, where it has been
established that such a condition results in lasting brain damage that may
196. See supra notes 153–71 and accompanying text.
197. Morse, supra note 148, at 22–23.
198. See supra Part I.B.
199. See generally Montana v. Egelhoff, 518 U.S. 37 (1996).
200. See Bennett, supra note 14, at 438.
201. See supra note 32 and accompanying text.
202. See Mandiberg, supra note 192, at 233.
204. See Morse, supra note 148, at 22.
205. See supra note 35 and accompanying text.
206. See Bennett, supra note 14, at 438.
207. See id.
affect mental state, likely violates a defendant’s fundamental right to due
process. While intoxication is a voluntary, transient condition—potentially
justifying imputing the mens rea of becoming intoxicated to an act
committed minutes or hours later—addiction endures.208 If the effects of
addiction cannot be considered in evaluating mental state, the act alone is
sufficient to establish liability.209 Such a result is not consistent with
traditions in criminal responsibility, suggesting that the due process analysis
for drug-addicted individuals should be differentiated from that of voluntary
intoxication in Egelhoff.210
Outlawing consideration of the effects of addiction in the mens rea
analysis likely violates a fundamental right, regardless of the status of the
doctrines of voluntary intoxication, in light of both the neuroscience
research suggesting that methamphetamine addiction does affect mens rea
as well as criminal law’s concern with subjective mental state. However,
even where the law acknowledges a right as fundamental, it may be
restricted where the state can demonstrate a compelling interest.211 One
such interest may be in reliable and efficient fact-finding.
C. Pragmatic Problems of Presenting Neuroscience to the Jury
Jurors are the court’s fact-finders and the foundation of evidentiary law is
in circumscribing what can and cannot be set before the jury. Scientific
evidence—particularly neuroscience—is often treated as presenting a
distinct risk.212 In the courtroom, presenting brain scans to validate expert
testimony is often met with resistance, “as if [defendants’] experts’
interpretations of brain scans are somehow less reliable than their experts’
unsubstantiated testimony.”213 Lawyers and nonlawyers alike are
concerned that neuroscience is “too complex and too technical” for
ordinary, untrained people to understand and apply.214 Or they worry that
the evidence will be used to draw overbroad inferences about individual
actors from data collected in group studies.215 The suggestion is that the
pragmatic problems posed by such evidence justify its limitation.
There is a belief among some courts and scholars that allowing evidence
of intoxication—and by extension, addiction—to disprove mental state is
particularly dangerous because juries cannot make subtle culpability
distinctions and are unduly influenced by scientific evidence.216
208. See supra notes 161–71 and accompanying text.
209. See supra note 35 and accompanying text.
210. See supra Part I.C.
211. See Bennett, supra note 14, at 438.
212. See Deborah Denno, The Place for Neuroscience in Criminal Law, in
PHILOSOPHICAL FOUNDATIONS OF LAW AND NEUROSCIENCE 69, 77–80 (Dennis Patter
Michael Pardo eds., 2016
213. Id. at 79.
214. Jones et al., supra note 17, at 730.
215. See id. at 731.
216. See Mandiberg, supra note 192, at 242–43 (“It is the use of the evidence to disprove
mental state, not the evidence itself, that some courts find inherently confusing; these courts
think such usage requires the jury to make unduly subtle distinctions.”).
“[N]euroscientific evidence should not be used to make fine-grained
culpability assessments at trial. It is beyond the qualifications of the jury in
our adversarial system of justice to make nuanced distinctions about where
a qualifying agent falls on the capacity spectrum.”217 However, the juror
does just that—make nuanced distinctions—in evaluating mental state in
every criminal trial. This fact-finding is precisely within the responsibility
and capability of the jury.
However, courts have expressed unease about juries’ capabilities as
well.218 Of particular concern to the Supreme Court is the possibility that
juries are unduly influenced by scientific evidence. In Egelhoff, Justice
Scalia noted that laws prohibiting consideration of intoxication in the mens
rea analysis are even more justified in modern times because juries
presented with evidence of intoxication “will be too quick to accept the
claim that the defendant was biologically incapable of forming the requisite
mens rea.”219 Neurological images from magnetic resonance imaging
(MRI) and positron emission tomography (PET) scans—with their bright
colors and perceived legitimacy—are often considered particularly
dangerous in their ability to confuse the jury.220
Interestingly, the opposite reasoning has been used to justify withholding
from the jury evidence of the effects of intoxication on mental states. For
example, a Minnesota court remarked that “we treat expert testimony on
intoxication and mental illness cases much the same. . . . [E]xpert opinion
testimony about the general effects of mental illness or intoxication is
ordinarily inadmissible because most jurors have some experience with
these conditions.”221 While in some cases neuroscience evidence is
inadmissible for its potential to confuse an unknowing jury, it is
inadmissible in others because the jury naturally has such knowledge. This
seasonal treatment suggests that it is the category of evidence itself, not its
potential value to the fact-finder, that influences its admissibility.
Other scholars strongly disagree with limiting neuroscience evidence in
the courtroom. Professor Deborah W. Denno, Founding Director of the
Neuroscience and Law Center at Fordham University School of Law,
wrote, “[A]lthough neuroscience brings unique insight to the law, there is
nothing about neuroscience that merits unique treatment by the law.”222
Others maintain that the best way to rectify concerns about jurors’ ability to
distinguish between mens rea culpabilities is by improving jury
instructions.223 One study found that small differences in wording of the
language used to communicate mens rea to jurors can significantly improve
accuracy in distinguishing between culpable mental states.224 This suggests
that careful construction of jury instructions on mens rea, the effects of
addiction, and the application of neuroscience evidence would likely
alleviate most of the concerns about juror’s distinguishing capabilities.225
As Minnesota Supreme Court Judge Sandra Gardebring articulated,
“Though a subjective state of mind may at times be difficult to determine,
there is no mystery to mens rea, the latinism notwithstanding. Jurors in
their everyday lives constantly make judgments on whether the conduct of
others was intentional or accidental, premeditated or not.”226 Judge David
L. Bazelon of the D.C. Circuit advocated a similar position.227 In
determining culpability, he acknowledged that there is “no simple, scientific
formula that will provide a clear-cut answer to every case” and stated that
we should just tell jurors the truth: the jury is to judge the defendant’s
blameworthiness, there is no “calibrated, easily-applied standard” to guide
their decision, and the question must be resolved with reference to the
jury’s “own understanding of community concepts of blameworthiness.”228
While allowing the consideration of addiction in the mens rea analysis
may complicate the jury’s assignation of liability, this is an insufficiently
compelling reason to eliminate such consideration altogether. Renowned
criminal law scholar Paul H. Robinson stated eloquently: “I agree that
complexity is to be avoided as much as possible. . . . But in the end, the
proper distribution of liability sometimes depends upon a concept that is
complex. . . . The law must be as complicated as are our notions of
justice.”229 Justice requires that criminal law incorporate scientific findings
into culpability analyses rather than ignore such discoveries for the sake of
IV. THE CASE FOR A DOCTRINE OF ADDICTION
This part advocates for a doctrine of addiction that adopts neuroscience
findings of the impact of addiction on cognition and behavior and
acknowledges addiction’s potential to affect mens rea. Specifically, this
Note argues that addiction should not be incorporated under the law’s
doctrines of intoxication. Instead, it should be acknowledged that addiction
does affect mens rea and its effect should be considered in the mens rea
analysis. Finally, this Note encourages the update of the MPC and
prescribes a section on addiction.
A. Addiction Is Distinct from Intoxication
and Should Not Be Incorporated Under the Law’s
Doctrines of Intoxication
Application of the doctrine of voluntary intoxication to drug-addicted
criminal defendants is inappropriate due to the significant differences
between acute intoxication and long-term addiction.230 Even if criminal
law’s doctrines of intoxication, limiting the relevance of intoxication to the
mens rea analysis,231 remain unchanged, these doctrines should not be
expanded so as to include such limitations on addiction. Addiction is
neither voluntary in the sense that we understand the term in reference to
voluntary intoxication nor is it transient or as temporally connected to the
act of drug ingestion as is intoxication.232 Therefore, the justifications for
doctrines of intoxication that limit or eliminate the relevance of intoxication
to the mens rea analysis do not apply to long-term drug addiction.
Voluntariness justifies doctrines that limit intoxication’s relevance to the
mens rea analysis.233 It is instinctively undesirable that a criminal
defendant might not satisfy the elements of an offense simply because his
voluntary intoxication rendered him unaware of the degree of risk involved
in his actions. Intoxicated actors can wreak havoc if they get behind the
wheel of a car, play around with a dangerous object, or attempt physical
contact with another person. Criminal law seeks to deter the act of
becoming so intoxicated that one cannot control himself or comprehend
situational risks.234 The temporal relationship between imbibing
intoxicating substances and the resultant intoxication, combined with the
truly voluntary nature of such an act, may provide a reasonable justification
for disallowing consideration of intoxication in the mens rea analysis, even
if such intoxication does affect mental state.235
The same reasoning cannot be extended to addiction. The fear of
addiction may deter some individuals from using drugs, but in the
population of drug users, the emergence of addiction is too variable to
230. See supra Part III.A–B.
231. See supra Part I.
232. See supra notes 153–71 and accompanying text.
233. See supra Part III.A.
234. See supra Part III.A.
235. See supra notes 147–52 and accompanying text.
expect such a policy to significantly deter the state of addiction.236 The line
between drug use and drug addiction is not well understood and is
influenced by a variety of social, environmental, and biological factors.237
While there may be a “safe” level of intoxication—thus, individuals may be
deterred from becoming too intoxicated—there is no safe level of addiction.
Furthermore, unlike the close temporal relationship between ingesting an
intoxicant, being intoxicated, and committing acts while intoxicated,
addiction is distinguished by its more tenuous connection between the
initial acts contributing to one’s status as an addict, developing addiction,
and offensive acts committed months or even years later.238 Therefore, the
state of addiction cannot be deterred in the same way that Egelhoff suggests
intoxication can be deterred.
A counterpoint may be that including addiction within doctrines of
intoxication is justified because it is sufficient to seek to deter all drug use
in order to deter addiction. However, plenty of addictive drugs are legal for
adults to purchase and consume.239 Whether the addictive substance is
alcohol, heroin, or methamphetamine, it is unrealistic for the success of a
doctrine to rest on the deterrence of all drug use. Therefore, deterrence
does not justify including addiction within the doctrines of intoxication, as
there is limited ability to deter addiction.
Furthermore, the state of being an addict is not voluntary in the same
sense as is the state of intoxication. Neuroscience evidence suggests that
the issues of voluntariness and choice are particularly nuanced for
drugaddicted individuals.240 Both the initiation and maintenance of addiction
are influenced by a host of environmental and biological factors that are
distinct from the direct effects of an intoxicating substance.241 Even when
the effects of the drug are not pleasurable, addicts may continue to feel a
compulsion to seek out the drug.242 Research on the dopaminergic system
involved in addiction suggests that repeated use of drugs leads to reflexive
behaviors, a relationship that is buoyed by the forming of complex
associations between cues and the drug.243 The result is that previously
neutral stimuli may themselves stimulate dopamine release and intense
cravings for the drug.244 This cycle may be heightened by the various
effects of the specific drug abused.245 Methamphetamine, for example,
contributes to severe emotion dysregulation, inhibitory dysfunction, and
236. See supra notes 153–71 and accompanying text.
237. See Baler & Volkow, supra note 153, at 559–60 (noting the complexity of the
physiological interactions in addiction).
238. See supra notes 153–71 and accompanying text.
239. For example, caffeine, nicotine, alcohol, and a variety of prescription opioids are all
addictive, yet legal. See generally Commonly Abused Drugs Chart, NAT’L INST. ON DRUG
Mar. 25, 2017)
240. See supra notes 153–71 and accompanying text.
241. See Baler & Volkow, supra note 153, at 559.
242. See id. at 560.
243. See id.
244. See id.
245. See id.
difficulty coping with stress.246 Each of these has been shown to increase
drug craving, and it is worth noting that the neurotransmitter systems
affected by methamphetamine are also disturbed by cocaine, heroin, and
alcohol.247 Although initial drug use is a choice, neither the emergence nor
maintenance of addiction is voluntary. Therefore, the justification for
criminal law’s doctrines of intoxication, which focuses on deterrence of the
voluntary act of becoming intoxicated, does not provide a similar
justification for applying those doctrines to addiction.
B. Addiction Does Affect Mental State and Should Be Considered in the Mens Rea Analysis
As discussed above, addiction results in significant damage to neural
structures and pathways that have a critical role in cognition and
behavior.248 The culpability terms of the MPC and the mens rea terms used
throughout American jurisdictions may require analysis of intent,
awareness, and probability.249 Neuroscience research reveals that each of
these is influenced by particular neural circuits and structures, many of
which may be damaged by drug addiction as has been specifically
demonstrated for methamphetamine addiction.250 It is at best naive to
suggest that drug addiction has no effect on mental state or the formation of
an offense’s requisite mens rea.
The extent of the effect of addiction on mental state may vary according
to many factors, including severity of addiction, type of drug, and
comorbidities.251 Any such analysis, therefore, could not be a simple
“check yes for addict” but would require the jury to carefully weigh the
persuasiveness of all evidence regarding the nature of the individual
defendant’s drug addiction and its potential effect on mental state.
Although there are valid concerns about jurors’ ability to comprehend such
complexities,252 that is precisely the role of the jury as fact-finder.253
Concerns about juror aptitude are not unique to neuroscience evidence, and
carefully constructed jury instructions may mitigate these issues.254 The
pragmatic concerns of such an analysis should not prevent its
implementation where it is necessary for a fair and just trial for all
The mens rea analysis has traditionally been a subjective inquiry in
American criminal law, designed to address the mental state of the
defendant at the time of commission of the offensive act.255 A doctrine that
would define the mental element of offenses to make addiction irrelevant,
246. See supra Part II.C.
247. See Okita et al., supra note 122, at 168.
248. See supra Parts II.C, III.B.
249. See supra Part I.A.
250. See supra notes 153–71 and accompanying text.
251. See Homer et al., supra note 77, at 302–03.
252. See supra notes 212–20 and accompanying text.
253. See supra notes 223–28 and accompanying text.
254. See supra notes 223–28 and accompanying text.
255. See supra note 32 and accompanying text.
as is allowed for intoxication under the Egelhoff doctrine,256 improperly
elevates the importance of actus reus over mens rea. This amounts to strict
liability for the act, with no consideration of the mental state of the actor.257
Such a doctrine is anathema to traditional offense definitions in American
criminal law. What is traditionally a subjective analysis for all defendants
is redefined to become an objective analysis for drug-addicted defendants
only.258 Moreover, this departs from fundamental principles of American
criminal law and potentially violates due process.
This Note does not suggest the elimination of criminal responsibility for
drug-addicted criminal defendants. Instead, it seeks to remind legal
institutions that mens rea remains a critical justification for criminal
liability, one that should not be manipulated for specific categories of
defendants. Nor should modern science be ignored for the sake of
simplicity.259 It may be that future scientific findings continue to
complicate the assignment of criminal culpability.260 However, the practice
of limiting the relevance of addiction to mental state renders the mens rea
analysis an unacceptable legal fiction now. Therefore, the potential effects
of addiction on mental state should be considered in the mens rea analysis.
Doctrines that would eliminate addiction’s relevance may violate the
constitutional rights of criminal defendants.
C. The MPC Should Be Updated to Reflect Current Science and Acknowledge the Effect of Addiction on Mental State
The drafters of the MPC relied on the science of their time when
developing the mens rea culpability categories and doctrine of intoxication,
which focuses almost exclusively on alcohol.261 While an immense
achievement in American criminal law at the time, both of these sections
are now outdated. “In promulgating a Model Penal Code, the American
Law Institute sought and obtained the trust and reliance of many states who
adopted their model code. Knowing the model to be seriously flawed, the
Institute has an obligation to address those flaws.”262
Immense advances in science in the time since its completion have led to
calls for an update in the MPC’s approach to mental state. Professor Denno
writes, “The failure to update the MPC further has resulted in a mens rea
provision that no longer mirrors current science if it is interpreted in the
way it was originally intended.”263 Although section 2.02’s reliance on
Freudian psychotherapy renders the MPC’s focus on “voluntary act” and
“conscious object” outdated, and the assignation of greater liability for
knowingly than recklessly is potentially at odds with the values of the
256. See supra Part I.B.2.
257. See supra note 204 and accompanying text.
258. See supra note 202 and accompanying text.
259. See supra note 229 and accompanying text.
260. See supra note 229 and accompanying text.
261. See supra Part I.B.1.
262. Robinson, supra note 229, at 43.
263. Denno, supra note 30, at 614.
everyday citizen,264 the MPC’s culpability terms are at least a workable
attempt to categorize mental states. What is no longer workable, however,
is the MPC’s ignorance of addiction. The ALI has updated portions of the
MPC from time to time.265 It is time for the ALI to reexamine the MPC’s
intoxication section and, crucially, include an additional section on
addiction that reflects modern neuroscience. This Note proposes adoption
of the following:
§ 2.X. Addiction.
(1) Addiction is not a defense unless it negatives an element of the
(2) Addiction does not, in itself, negative an element of the offense but
requires additional proof that the effect of the addiction is such that it
negatives an offense’s requisite mens rea. The burden of proof for
such a showing lies with the defendant.
(3) A criminal defendant’s addiction to intoxicating substances is
relevant to the analysis of the mental culpability or mens rea elements
of an offense. Factors that may be considered in analyzing the
potential effect of addiction on mens rea include but are not limited to:
(a) Severity of addiction. Indicia of severity may include length of
addiction, frequency of drug use, and history of overdose or
(b) Drug(s) of choice. Expert testimony and scientific research
regarding the neural, cognitive, and behavioral effects of the
specific drug(s) abused are encouraged.
(c) Neurological damage observed in defendant. Brain scans and
expert testimony are not dispositive but may assist the fact-finder.
(d) Comorbidities. These may include a history of depression,
bipolar disorder, schizophrenia, psychosis, or any other relevant
disease or disorder.
(e) Any other factor(s) deemed relevant and significant by the
scientific and legal communities.
(4) In considering these factors, the goal is to elucidate the subjective
mental state of the defendant during the commission of the offense for
which he has been charged.
The ALI’s adoption of such a provision on addiction will hopefully be a
call to action for the state and federal systems. In the process, the ALI
might consider whether its culpability terms and intoxication sections also
require an update to reflect modern values and scientific understanding. At
the very least, it is imperative that the ALI acknowledge the vast amount of
264. See supra note 224 and accompanying text.
265. The ALI is currently “re-examining Article 213 of the Model Penal Code, which was
ahead of its time when approved by ALI in 1962, but is now outdated and no longer a
reliable guide for legislatures and courts.” Model Penal Code: Sexual Assault & Related
Offenses, ALI, https://www.ali.org/projects/show/sexual-assault-and-related-offenses/
visited Mar. 25, 2017)
research on the effects of addiction on cognition and behavior. As the
selfproclaimed “leading independent organization in the United States
producing scholarly work to clarify, modernize, and improve the law,”266
the ALI has a professional and moral obligation to address a fundamental
flaw existing within one of their most important contributions, the Model
American criminal law is outdated in its approach to the effect of drugs
on the mens rea analysis. Modern neuroscience findings reveal extensive
differences between acute intoxication and drug addiction, particularly with
regard to voluntariness and effects on neurophysiology, cognition, and
behavior. However, the Modern Penal Code, U.S. Supreme Court, common
law, and legislatures all fail to recognize these distinctions in their criminal
law doctrines. It is time for legal acknowledgment and adoption of
neuroscience findings, particularly with regard to the relevance of addiction
to the mens rea analysis. Addiction should be distinguished from
intoxication and a new doctrine of addiction should be adopted. Any
doctrine of addiction must recognize the relevance of drug addiction to the
mens rea analysis and incorporate a subjective analysis of the potential
influence of addiction on the mental state of the criminal defendant in
question. Anything less renders delusory the mens rea analysis for
drugaddicted criminal defendants and may result in fundamental injustice.
A. Mens Rea in the Model Penal Code........................................ 2421
B. The Law on Drugs .................................................................. 2422 1. The MPC on Drugs: Voluntary Intoxication................... 2423 2. The Common Law on Drugs: Specific Intent
Negation .......................................................................... 2424 3. The Supreme Court on Drugs: Montana v . Egelhoff....... 2425
II. METHAMPHETAMINE ADDICTION AND THE BRAIN ........................... 2426
A. Why Focus on Methamphetamine?. ........................................ 2427
Methamphetamine Use and Abuse........................................ 2429
Deficits .................................................................................. 2430 1 . Methamphetamine Addiction Causes Severe Damage to
the Critical Dopaminergic System .................................. 2430 2 . Methamphetamine Addiction : Emotion Dysregulation,
Aggression , Impulsivity, and Psychosis.......................... 2432
A. The Nuances of Voluntary Addiction ...................................... 2434
B. Does Addiction Affect Mens Rea? .......................................... 2437
to the Jury ............................................................................. 2441
IV. THE CASE FOR A DOCTRINE OF ADDICTION.. ................................... 2444
Incorporated Under the Law's Doctrines of Intoxication ..... 2444
Considered in the Mens Rea Analysis................................... 2446
on Mental State ..................................................................... 2447
CONCLUSION ........................................................................................... 2449 1 . See Lindsey Bever & Amy B. Wang , Mother Whose Baby Died During a Meth-
Fueled Search for Her Lover Is Found Guilty of Murder, WASH . POST (Sept. 17 , 2016 ),
mother-accused-in-newborns-death-during-meth-fueled-search-for-lover/?utm_term= . 9b15
e4094ff6 [https://perma.cc/Z6MH-84EZ ]. 2. See id. 3. See id. 4. See id. 5 . See Darrell Smith , Samantha Green Guilty of Murder in Death of Infant
Son , SACRAMENTO BEE ( Sept . 16, 2016 ), http://www.sacbee.com/news/local/crime/
article102222787.html [https://perma. cc/2WNX-U9Q2]. 6. Id. 7. See id. 8. See id. 9 . See Darrell Smith , Expert Says Drug-Induced Psychosis Led Samantha Green into
Slough with Infant Son , SACRAMENTO BEE (Sept. 7 , 2016 ), http://www.sacbee.com/
news/local/crime/article100532587.html [https://perma.cc/XU7F-LM5A ]. 10. See Smith, supra note 5 . 11. Jade Wolkansky , Jury Finds Green Guilty of Second Degree Murder, DAVIS
VANGUARD (Sept. 16 , 2016 ), http://www.davisvanguard.org/ 2016 /09/jury-finds-green-
guilty-of-second-degree-murder/ [https://perma.cc/CN3U-QKWZ]. 12 . See id. 13 . See Lauren Keene, Samantha Green Sentenced to Prison; Bid for New Trial Denied,
DAVIS ENTERPRISE (Dec. 11 , 2016 ), http://www.davisenterprise.com/local-news/crime-fire-
N-YMBW ]. 14 . Elizabeth Bennett , Neuroscience and Criminal Law: Have We Been Getting It
Wrong for Centuries and Where Do We Go from Here?, 85 FORDHAM L . REV. 437 , 437 - 38
( 2016 ) (quoting BLACK'S LAW DICTIONARY (5th ed. 1979 )). 15 . See id. 16 . Neuroscience involves the study of the physiology, biochemistry , anatomy, or
behavior. See Neuroscience , MERRIAM-WEBSTER'S DICTIONARY , https://www.merriam22. See MARKUS D. DUBBER , AN INTRODUCTION TO THE MODEL PENAL CODE 2 (2d ed.
2015 ) ; see also id. at 44 (describing section 2.02 as “the heart of the Model Penal Code” ). 23 . Paul H. Robinson & Markus D. Dubber , The American Model Penal Code: A Brief
Overview , 10 NEW CRIM. L. REV. 319 , 320 ( 2007 ). 24 . See id. at 327 . 25. See id. 26 . See DUBBER , supra note 22, at 44 . 27. See Paul H. Robinson , A Brief History of Distinctions in Criminal Culpability, 31
HASTINGS L.J . 815 , 815 ( 1980 ). 28 . See Robinson & Dubber, supra note 23, at 335 . 29. Id . 30 . See generally Deborah W. Denno, Criminal Law in a Post-Freudian World, 2005 U.
ILL. L. REV . 601 . Freudian psychoanalysis, which dominated psychiatry in the 1950s and
1960s, is rooted in a fundamental distinction between conscious and subconscious thought .
See id . at 616 , 619 - 20 . 31 . See id. at 621. Interestingly, the MPC does not define the term “voluntary” but
instead provides examples of acts that are considered not voluntary . Id. at 620 . Moreover,
while the MPC also fails to define “unconsciousness,” “the MPC's Commentaries do make 40 . 518 U.S. 37 ( 1996 ). 41 . See MODEL PENAL CODE § 2 .08, at 349 ( AM . LAW INST., Official Draft and Revised
Comments 1985 ). The MPC defines intoxication as “a disturbance of mental or physical
capacities resulting from the introduction of substances into the body . ” Id . 42. See DUBBER , supra note 22, at 69 . 43. See MODEL PENAL CODE § 2 .08, at 349 (“ Intoxication of the actor is not a defense
unless it negatives an element of the offense .”); DUBBER, supra note 22, at 69 . 44. DUBBER, supra note 22, at 69 . 45. See MODEL PENAL CODE § 2 .08, at 349. Exceptions are involuntary intoxication,
is susceptible.” Id. § 2 . 08 ( 5 ), at 349 . 46. See id. § 2 . 08 ( 2 ), at 349. “ When recklessness establishes an element of the offense,
been aware had he been sober, such unawareness is immaterial . ” Id. 47. Id. § 2.08 cmt. 1, at 354. 48. See id. § 2.08 cmt. 1, at 352-59. 49. Id. § 2.08 cmt. 4 , at 366. 50. Id . (emphasis added). “Opiates are quieting drugs that repress hostile urges, create a
MED. ASS'N, REPORT ON NARCOTIC ADDICTION 24 ( 1957 )). 51 . See id. § 2 .08 cmt. 1, at 353-56 (describing the distinction between specific and
formulation and the usual formulation seems to be the same ). 52 . See Eric A. Johnson, Understanding General and Specific Intent: Eight Things I
Know for Sure , 13 OHIO ST. J. CRIM . L. 521 , 529 ( 2016 ). 53 . See id. 54 . Id . (quoting Regina v . Monkhouse ( 1849 ) 4 Cox C .C. 55 , 56). 55. Id. at 522 (quoting PAUL ROBINSON, CRIMINAL LAW DEFENSES § 65 (e), at 298
( 1984 )). 56 . See id. 57 . See id. at 524- 25 . Johnson's illuminating article on general and specific intent
require “proof that the defendant 'intended to commit some further act . '” Id. at 527-30. 58. See id. at 529 . 59. Id. at 521 , 529 - 30 . 60 . See MODEL PENAL CODE § 2.08 cmt. 1 , at 353-56 (AM. LAW INST ., Official Draft
and Revised Comments 1985 ) (describing various offenses and how the net effects of the 71 . See supra Part I.B. 72. See Egelhoff , 518 U.S. at 48 ( plurality opinion) (noting that only one-fifth of states
either never adopted the common law intoxication rule or had recently abandoned it ). 73. See supra Part I.B.1-2 . 74 . Even a cursory search through statutes and court rules shows that some states use the
MPC. See CAL . PENAL CODE § 29.4 (West 2016 ) ; CONN. GEN. STAT . ANN. § 53a- 7 (West
2017 ) ; ME. REV. STAT . ANN. tit. 17 , § 37 ( 2017 ); S.D. CODIFIED LAWS § 22-5-5 ( 2016 );
TENN. CODE ANN. § 39 - 11 -503 ( West 2016 ) ; N.M. CT . R. 14 - 5105 ( providing an updated
ANN. § 13 - 503 ( 2016 ) ; IND . CODE ANN. § 35-41-2-5 (West 2016 ) ; MONT . CODE
ANN. § 45 -2-203 ( West 2017 ). Hawaii “follows the position taken by Judge Learned Hand
relevant,' ” including recklessness . HAW. REV. STAT . ANN. § 702 - 230 ( West 2016 ) (quoting
MODEL PENAL CODE § 2.08 cmt. 3, at 6-7 (AM . LAW INST., Tentative Draft No. 9 , 1959 )). 75 . See Egelhoff, 518 U.S. at 56 . 76. Id . (quoting Powell v . Texas , 392 U.S. 514 , 536 ( 1968 )). 77 . See Bruce D. Homer et al., Methamphetamine Abuse and Impairment of Social
Implications , 134 PSYCHOL. BULL. 301 , 301 ( 2008 ). 78 . See Alasdair M. Barr et al., The Need for Speed: An Update on Methamphetamine
Addiction , 31 J. PSYCHIATRY & NEUROSCIENCE 301 , 301 ( 2006 ). 80 . Barr et al., supra note 78 , at 308 . 81. Pub . L. No. 111 - 268 , 120 Stat. 192 (codified at 21 U.S.C. § 830 ( 2012 )). 82 . See Jane Carlisle Maxwell & Mary-Lynn Brecht , Methamphetamine: Here We Go
Again?, 36 ADDICTIVE BEHAVIORS 1168 ( 2011 ). Once desired precursors were not available,
Stuff-Type Deal ( AMC television broadcast Mar. 9 , 2008 ). 83 . This Note uses methamphetamine as a paradigmatic drug . The conclusions of this
generally. 84. See infra notes 87 , 95 and accompanying text. 85. See Pete Williams , DEA Finds Heroin Use Skyrocketing Across U.S. , NBC NEWS
(Nov. 4 , 2015 ), http://www.nbcnews.com/news/us-news/ dea-finds-heroin-use-skyrocketing-
n457336 [https://perma.cc/AP2K-3GGB ]. 86. See id. 87 . Number of Crimes Committed by Methamphetamine Addicts 'Truly Frightening,'
WA's Top Judge Says , ABC RADIO PERTH (Feb. 25 , 2015 ), http://www.abc.net.au/news/
2015-02-25/wa-chief -justice-says-ice- problem- truly-frightening/6261310 [https://perma.cc/
4U4L-GQTW] . In Western Australia, where methamphetamine is the “drug of choice ,”
Chief Justice Wayne Martin states that 95 percent of armed robberies and nearly half of
a recipe you can get off the internet . ” Id . 88. See generally J. Cobb Scott et al., Neurocognitive Effects of Methamphetamine: A
Critical Review and Meta-Analysis , 17 NEUROPSYCHOLOGY REV . 275 , 275 ( 2007 ). 89. See supra note 79 . 90. Cocaine “works principally by blocking plasma membrane transporters that reuptake
monoamines.” Barr et al., supra note 78 , at 302 . 91. Id . ; see also infra Part II.C. 92 . See Barr et al., supra note 78 , at 302. Cocaine has an elimination half-life of 1-3
hours, while methamphetamine's elimination half-life is 8-13 hours . See id. 93 . See Homer et al., supra note 77 , at 301 . 94. See infra Part II.C. 95 . See , e.g., Aja Goere , Murderer Who Traded Another Man's “Life for
Methamphetamine” Sentenced to Life in Prison, KPAX . COM (Dec. 6 , 2016 ),
methamphetamine-sentenced-to-life-in-prison [https://perma .cc/DQ9H-UQG9] ; Amy Renee
Leiker , Oral Arguments Set in Death-Row Inmate's Appeal , WICHITA EAGLE (Dec. 7 , 2016 ),
http://www.kansas.com/news/local/crime/article119462028.html (listing the status of death-
upheld by the Kansas Supreme Court in July 2016 ) [https://perma.cc/VPE7-WHQ8]; Laura
Zuckerman , Mother Sentenced to 12 Years in Baby's Meth Death , POST REG. (Dec . 22,
2016 ), http://www.postregister.com/articles/news-daily -email-todays-headlines-west/2016/
12 /22/mother-sentenced-12 - years -baby's-meth [https://perma .cc/ZM5G-8RWT ]. 96. See supra note 37 and accompanying text. 97 . See Stephanie C. LoConto , Methamphetamine: The Physical Effects, PROSECUTOR,
Mar .-Apr. 2007 , at 30 , 30 - 31 ( providing a broad overview of the physical effects of
methamphetamine) . 98 . Id. at 30 (explaining that the neurotransmitters dopamine, epinephrine,
methamphetamine's inhibition of neurotransmitter reuptake into the nerve terminal ). 99 . See id.; see also Homer, supra note 77 , at 301 . 100. See LoConto , supra note 97, at 30-31; see also Homer, supra note 77 , at 302 . 101. See Barr et al., supra note 78 , at 303 . 102. See LoConto , supra note 97, at 31. Interestingly, recent historical research has
on Hitler and Meth: Book Says Nazis Were Fueled by Drugs , N.Y. TIMES (Dec. 9 , 2016 ),
http://www.nytimes.com/ 2016 /12/09/books/high-on -hitler-and-meth-book-says-nazis-were-
fueled-by-drugs .html [https://perma.cc/FR3C-TF4P]. “ Hopped-up soldiers would sprint
later gloat that his men had stayed awake for 17 straight days . ” Id . 103. See Meth's Devastating Effects: Before and After , CBS NEWS,
Mar. 25 , 2017 ) [https://perma.cc/6RZ2- P66C ]. 104. See LoConto , supra note 97, at 31 . 105. Id . 106 . See id. at 31 . 107. See , e.g., Barr et al., supra note 78; Homer et al., supra note 77 . 108. See Barr et al., supra note 78 , at 304-05; Homer et al., supra note 77 , at 302 . 109. See Min Lin et al., Methamphetamine Regulation of Firing Activity of Dopamine
Neurons , 36 J. NEUROSCIENCE 10 , 376 , 10 , 376 ( 2016 ). 110 . See Linda Chang et al., Structural and Metabolic Brain Changes in the Striatum
Associated with Methamphetamine Abuse , 102 ADDICTION 16, 16 ( 2007 ) (noting that
id. at 16-17 . 111 . See Barr et al., supra note 78 , at 306; Thomas E. Nordahl et al., Neuropsychological
15 J. NEUROPSYCHIATRY & CLINICAL NEUROSCIENCES 317 , 319 ( 2003 ) ; Scott et al ., supra
note 88, at 278-79 . 112 . See Nordahl et al., supra note 111 ( discussing methamphetamine-induced
neurotoxicity) . 113 . See Lin et al., supra note 109 , at 10 , 376 . 114. See David Sulzer et al., Mechanisms of Neurotransmitter Release by Amphetamines:
A Review , 75 NEUROBIOLOGY 406 ( 2005 ) (describing how the drug class of amphetamines
causes the release of neurotransmitters) . 115 . A substrate is a substance acted upon by an enzyme . See Substrate , MERRIAM-
visited Mar . 25 , 2017 ) [https://perma.cc/EC8X-WCZJ]. As a substrate, methamphetamine
supra note 109 , at 10 , 376 . 116. See Lin et al., supra note 109 , at 10 , 376 . Methamphetamine “increases extracellular
dopamine via the transporter . ” Id . 117. See id. Methamphetamine regulates the excitability of dopaminergic neurons by
altering membrane channel activity . See id. at 10 , 387 - 89 . Methamphetamine also stimulates
decrease. See id. at 10 , 389 . 118. See Nordahl et al., supra note 111 , at 319 . 119. See id. 120 . See Yoshimoto Sekine et al., Brain Serotonin Transporter Density and Aggression in
Abstinent Methamphetamine Abusers, 63 ARCHIVES GEN. PSYCHIATRY 90 ( 2006 ) (discussing
the effect of methamphetamine addiction on serotonin transporter density in the brain ). 121 . See generally Barr et al., supra note 78; Homer et al., supra note 77 . 122. See , e.g., Barr et al., supra note 78 , at 306; Homer et al., supra note 77 , at 303;
Buyean Lee et al., Striatal Dopamine D2/D3 Receptor Availability Is Reduced in
Methamphetamine Dependence and Is Linked to Impulsivity, 29 J. NEUROSCIENCE 14 , 734
( 2009 ) ; Kyoji Okita et al ., Emotion Dysregulation and Amygdala Dopamine D2-Type
Receptor Availability in Methamphetamine Users, 161 DRUG & ALCOHOL DEPENDENCE 163
( 2016 ). 123 . See Okita et al., supra note 122, at 164. 124. See id. at 163-64 . 125 . See Nordahl et al., supra note 111 , at 319 , 321 - 22 . 126 . See generally Michael E. Ballard et al., Low Dopamine D2/D3 Receptor
Methamphetamine Dependence , INT'L J. NEUROPSYCHOPHARMACOLOGY 1 (May 2015 ),
https://academic.oup.com/ijnp/article/675342/ Low-Dopamine-D2-D3- Receptor-Availability-
is [https://perma.cc/P8ZG-DLD2]. 127. See Okita et al., supra note 122 , at 166. Decreased D2-type dopamine receptor
Functional Connectivity and Ventral Striatal Dopamine D2-Type Receptors : Link to
Impulsivity in Methamphetamine Users, 21 MOLECULAR PSYCHIATRY 1554 , 1554 ( 2016 ). 128 . See Okita et al., supra note 122 , at 164 . 129. Lee et al., supra note 122 , at 14 , 734 . 130. See id. at 14 , 734 - 35 , 14 ,738 (finding a fundamental negative correlation between
impulsivity and striatal D2/D3 receptor in humans and suggesting that methamphetamine's
negative impact on the D2/D3 receptor system promotes impulsivity); see also Kohno et al .,
supra note 127 , at 1557-58 ( finding upregulation of midbrain activity-likely through the
combination of low striatal D2-type receptor availability, reduced dopamine availability, and
positively correlated with impulsivity) . 131 . See Uri Maoz & Gideon Yaffe , What Does Recent Neuroscience Tell Us About
Criminal Responsibility ?, 3 J.L. & BIOSCIENCES 120 , 135 - 36 ( 2016 ). 132 . See id. 133 . See Doris E. Payer et al., Neural Correlates of Affect Processing and Aggression in
Methamphetamine Dependence , 68 ARCHIVES GEN. PSYCHIATRY 271 , 272 ( 2011 ). 134 . See id. 135 . See Mary-Lynn Brecht & Diane M. Herbeck , Methamphetamine Use and Violent
Behavior: User Perceptions and Predictors, 43 J. DRUG ISSUES 468 , 477 - 78 ( 2013 ) ; see
also Payer et al., supra note 133 , at 277 ( replicating findings that methamphetamine-
dependent individuals self-report higher aggression than controls do) . 136 . See Payer et al., supra note 133 , at 272 . 137. See id.; Sekine et al., supra note 120 , at 90 (“ Protracted abuse of methamphetamine
aggression, even in currently abstinent abusers . ”) . 138 . See Payer et al., supra note 133 , at 278- 79 . Scientific models of aggression translate
influenced by methamphetamine addiction . See id. at 271 . 139. See id. at 279. This study found a particular region of the prefrontal cortex-the
id. 145. See supra note 44 and accompanying text. 146. See Egelhoff , 518 U.S. at 58 (Ginsburg, J., concurring) . 147. See id. at 49-50 (plurality opinion) . 148 . United States v. Brawner , 471 F.2d 969 , 1002 (D.C. Cir . 1972 ) (stating that the court
Reason : Addiction, Agency and Criminal Responsibility, 56 INQUIRY 490, 497 ( 2013 )
a passive victim” of “biological or environmental variables”). 149. See Carissa Byrne Hessick & Douglas A. Berman, Towards a Theory of Mitigation,
96 B.U. L. REV . 161 , 175 - 80 , 183 - 85 ( 2016 ) (discussing justifications for doctrines of
diminished capacity) . 150. See MODEL PENAL CODE § 2.08 cmt. 1, at 359 (AM. LAW INST ., Official Draft and
Revised Comments 1985 ); see also Egelhoff, 518 U.S. at 49- 50 . 151. MODEL PENAL CODE § 2.08 cmt. 1 , at 359. 152. Egelhoff , 518 U.S. at 49- 50 . 153 . See Ruben D. Baler & Nora D. Volkow , Drug Addiction: The Neurobiology of
Disrupted Self-Control , 12 TRENDS MOLECULAR MED . 559 , 559 ( 2007 ). 174 . See Stroman v. Thaler, No. 3 : 05 -CV-1616 -D , 2009 WL 3075168, at *6- 7 ( N.D. Tex .
Sept. 28 , 2009 ). 175. A claim of ineffective assistance of counsel is a constitutional claim of a denial of a
Washington , 466 U.S. 668 , 686 ( 1984 ) (quoting McMann v . Richardson , 397 U.S. 759 , 771
n. 14 ( 1970 )). 176 . See Bonnifield v. Lewis, No. C 12 - 3857 PJH (PR) , 2014 WL 1101658, at *12, * 16
(N.D. Cal . Mar. 18 , 2014 ) (denying the petition for a writ of habeas corpus, but granting a
certificate of appealability) . 177 . See id. (denying a prisoner's constitutional claim that trial counsel was ineffective
claim among those satisfying the certificate of appealability standard) . 178. See id. 179 . See supra Part II.C. 180 . See DUBBER , supra note 22, at 59- 61 . 181 . See id. at 55. 182. MODEL PENAL CODE § 2.02 cmt. 2, at 233 (AM. LAW INST ., Official Draft and
Revised Comments 1985 ) (emphasis added) . 183 . See DUBBER , supra note 22, at 59-60. 184. MODEL PENAL CODE § 2.02 cmt. 3 , at 236- 37 . The MPC Comments emphasize that
the level of certainty of the risk is a subjective analysis . See id. As the Comments note, both 217 . Peggy Sasso , Criminal Responsibility in the Age of “Mind-Reading,” 46 AM. CRIM.
L. REV . 1191 , 1223 ( 2009 ). 218 . Courts throughout the United States have expressed concern about a juror's ability to
make culpability distinctions . See, e.g., Bethea v . United States , 365 A.2d 64 , 89 - 90 (D.C.
1976 ) (“The potential impact of psychiatric evidence in an area so critically close to the
subtle distinction between mental states . . . .”); State v . McKenzie , 581 P.2d 1205 , 1233
(Mont . 1978 ) (stating that “psychiatric evaluation as to subtle gradations of mental
juror”) , vacated, 443 U.S. 903 ( 1979 ); Steele v . State, 294 N.W.2d 2 , 9 (Wis. 1980 ) (“Judge
classifications of human behavior . . . .” (quoting Curl v . State , 162 N.W.2d 77 , 93 (Wis.
1968 ))). 219 . Montana v. Egelhoff , 518 U.S. 37 , 50 - 51 ( 1996 ). 220 . See Ruben C. Gur et al., A Perspective on the Potential Role of Neuroscience in the
Court , 85 FORDHAM L. REV. 547 , 571 ( 2016 ); Jones et al., supra note 17 , at 731 . 221. State v. Provost , 490 N.W.2d 93 , 103 (Minn. 1992 ). 222 . Denno, supra note 212, at 81 . 223. See Matthew R. Ginther et al., The Language of Mens Rea , 67 VAND. L. REV. 1327 ,
1358 ( 2014 ). 224 . See id. at 1363. Interestingly, even once the participants were able to distinguish
harm knowingly or instead recklessly . ” Id. at 1363-64. 225. See id. 226. Provost , 490 N.W.2d at 101 (explaining why the court believes expert opinion
testimony is not helpful in determining whether a defendant formed intent ). 227 . See United States v. Brawner , 471 F.2d 969 , 1012 (D.C. Cir . 1972 ) (Bazelon , J. ,
concurring) . 228. Id . 229 . Paul H. Robinson , In Defense of the Model Penal Code: A Reply to Professor
Fletcher , 2 BUFF. CRIM . L. REV. 25 , 35 ( 1998 ).