Hijacked: Addiction, the Brain, and the Question of Criminal Responsibility

In 1957, a man named Lawrence Robinson was stopped by Los Angeles police officers who observed needle marks on his arm. He was not caught using drugs. He was not in possession of drugs. He was arrested for being a drug addict, which was a criminal offense under California law at the time.

He was convicted and sentenced to ninety days in jail.

Five years later, the Supreme Court of the United States ruled that convicting a person simply for the status of being addicted to drugs violated the Eighth Amendment's prohibition on cruel and unusual punishment. The Court compared it to criminalizing a person for having a mental illness or a disease. [1]

That decision, Robinson v. California, was one of the most significant moments in the legal history of addiction. It suggested that the law was beginning to understand something that neuroscience would spend the next several decades confirming: that addiction is not simply a moral failure or a series of bad choices. It is a condition of the brain.

What the law has done with that understanding since is a story full of contradictions.

What Addiction Is

For most of the twentieth century, addiction was understood primarily as a problem of willpower. A person who could not stop using drugs or alcohol was seen as weak, self-indulgent, or morally compromised. Treatment, where it existed at all, was often punitive.

The scientific understanding has shifted dramatically. The American Society of Addiction Medicine, the American Medical Association, and the American Psychiatric Association all classify addiction as a chronic brain disorder, characterized by compulsive substance use despite harmful consequences, driven by changes in brain structure and function that develop over time. [2]

This is not a metaphor. The brain changes are measurable, documented, and consistent across substances and populations.

Lens One: The Scientific Evidence

The evidence that addiction produces lasting changes in the brain is now extensive enough that it is no longer scientifically contested, even if it remains legally and culturally contested.

Longitudinal neuroimaging studies have shown that people with substance use disorders exhibit measurable reductions in gray matter volume in the prefrontal cortex, reduced activity in circuits responsible for inhibitory control, and structural changes in the dopamine system that persist long after the person has stopped using the substance. These changes are not present before addiction develops in the same degree, and they worsen with the duration and severity of use. [3]

Research on relapse rates is particularly relevant for the law. Even among people who are highly motivated to stop using substances, who have completed treatment, who understand the consequences clearly, and who have strong social support, relapse rates remain high. Studies of opioid use disorder, for example, show relapse rates between forty and sixty percent in the year following treatment. [4] For a legal system that interprets continued drug use as evidence of ongoing choice, this statistic is worth sitting with. If choice alone governed the behavior, motivated people with treatment and support would not relapse at these rates.

The science also shows that vulnerability to addiction is not evenly distributed. Genetic factors account for an estimated forty to sixty percent of a person's risk for developing an addiction. Early childhood trauma, adverse childhood experiences, and stress exposure are among the most powerful environmental risk factors. People do not choose their genetics or their childhood environments. [5]

Lens Two: The Neuroscience

To understand why addiction makes stopping so difficult even for people who want to stop, you need to understand what the brain's reward system is and what substances do to it.

The dopamine system is the brain's primary mechanism for motivating behavior. When you do something that promotes survival or wellbeing, such as eating, connecting socially, or achieving a goal, the brain releases dopamine. This creates a signal of reward that motivates you to repeat the behavior. The system is designed to respond to natural rewards that arrive in moderate amounts over time.

Addictive substances flood this system with dopamine at levels far beyond what any natural reward produces. Cocaine, for example, produces dopamine surges that are roughly ten times greater than those produced by natural rewards. The brain responds to this flooding by reducing the number of dopamine receptors and decreasing its own dopamine production in an attempt to compensate. [6]

The result is a brain that can no longer experience normal levels of pleasure from natural rewards, while simultaneously having developed a powerful conditioned response to the cues associated with drug use. Seeing a location, a person, or an object associated with past use triggers intense craving that originates not in conscious deliberation but in automatic brain processes operating below the level of awareness.

At the same time, chronic substance use damages the prefrontal cortex, the region responsible for exactly the capacities needed to resist those cravings: impulse control, long-term planning, the ability to weigh future consequences against immediate desires. [7] The substance use disorder systematically impairs the very brain systems that would allow a person to override the compulsion it creates.

This is the neurological trap of addiction. The drug damages the brain's capacity for self-regulation while simultaneously creating powerful automatic responses that demand the behavior. A person caught in this cycle is not simply making a series of bad decisions. They are operating with a brain that has been structurally altered in ways that make the behavior increasingly compulsive and the capacity for voluntary control increasingly compromised.

Lens Three: The Legal Interpretation

The law's response to addiction has been, and remains, deeply conflicted.

Robinson v. California established that the state cannot punish a person merely for the status of addiction. But the following decade, in Powell v. Texas in 1968, the Supreme Court ruled that states could still criminalize conduct associated with addiction, in that case public intoxication. [8] Justice Thurgood Marshall, writing for the plurality, acknowledged the evidence that alcoholism involves a loss of control but argued that the Court was not prepared to use the Constitution to resolve what was fundamentally a policy and scientific question still under debate.

That holding set the pattern for how the law has treated addiction ever since. Addiction cannot be criminalized as a status. But the behaviors it produces can be, even when those behaviors are the direct expression of a compulsion the person cannot fully control.

The practical consequence has been mass incarceration for drug offenses. At the peak of the War on Drugs, the United States was incarcerating people for drug offenses at rates that dwarfed every other developed nation. People with substance use disorders filled jails and prisons rather than treatment facilities. Incarceration, which removes access to substances by force, does nothing to address the neurological changes that drive addiction, which is one reason why people released from incarceration face sharply elevated overdose risk in the weeks immediately following release, as tolerance has decreased but the brain's compulsion has not. [9]

Drug courts emerged in the 1990s as an attempt to redirect people with substance use disorders toward treatment rather than incarceration. They represent the legal system's most significant structural acknowledgment that addiction requires a different response than ordinary criminal conduct. Research on drug court outcomes has generally shown reduced recidivism and improved public health outcomes compared to standard prosecution. [10] But drug courts reach only a fraction of the people with addiction-related charges, and their availability is uneven across jurisdictions.

The deeper legal question, which courts have not resolved, is whether the neurological impairments associated with addiction are severe enough to qualify as a mitigating factor in sentencing, or even, in the most severe cases, as a factor affecting criminal responsibility. If a brain with serious prefrontal cortex impairment and a powerful automated compulsion is less capable of voluntary control than a brain without these features, that difference seems legally relevant. The law has not yet developed a consistent framework for addressing it.

Putting All Three Lenses Together

The scientific evidence shows that addiction produces measurable, lasting changes in the brain systems governing reward, motivation, and impulse control. The neuroscience explains the mechanism: dopamine system dysregulation creates compulsive behavior while prefrontal cortex damage undermines the capacity to override it. The law acknowledged in 1962 that addiction cannot be treated as a simple moral failing, then spent the following decades building a criminal justice apparatus that functionally treats it as exactly that.

The tension at the center of this post is not easy to resolve. Acknowledging that addiction impairs voluntary control does not mean that no one with addiction is responsible for anything. It means that responsibility exists on a spectrum, that neurological impairment is relevant to where a person falls on that spectrum, and that a system designed around punishment alone is not equipped to address a condition that is fundamentally biological.

The opioid epidemic of the late 2010s shifted public discourse on addiction in the United States in ways that decades of advocacy had not. Communities that had previously supported harsh drug sentences were suddenly watching their own family members caught in the same cycle. The political language around addiction shifted toward disease and treatment. Whether the legal system will follow that shift, with consistency and structure rather than case by case exception, remains an open question.

What the neuroscience establishes is that the question of how much choice is involved in addictive behavior is not a moral question that individuals can simply answer by trying harder. It is a question about what the brain is doing, and what the brain is capable of, under specific neurological conditions. The law has always claimed to be interested in that question. It has not always been willing to follow where the answer leads.

The next post will examine implicit bias in the courtroom, and ask what neuroscience has to say about the unconscious racial assumptions that may be shaping legal outcomes without anyone in the room being aware of it.

Sources

[1] Robinson v. California, 370 U.S. 660 (1962): supreme.justia.com/cases/federal/us/370/660

[2] American Society of Addiction Medicine, Definition of Addiction, 2019: asam.org/quality-care/definition-of-addiction

[3] Volkow, N.D. et al., "Neurobiologic Advances from the Brain Disease Model of Addiction," New England Journal of Medicine, 2016: nejm.org/doi/full/10.1056/NEJMra1511480

[4] McLellan, A.T. et al., "Drug Dependence, a Chronic Medical Illness," JAMA, 2000: jamanetwork.com/journals/jama/fullarticle/193214

[5] NIH National Institute on Drug Abuse, "Genetics and Epigenetics of Addiction": nida.nih.gov/publications/drugfacts/genetics-epigenetics-addiction

[6] Volkow, N.D. and Morales, M., "The Brain on Drugs: From Reward to Addiction," Cell, 2015: cell.com/cell/fulltext/S0092-8674(15)00975-X

[7] Goldstein, R.Z. and Volkow, N.D., "Dysfunction of the prefrontal cortex in addiction," Nature Reviews Neuroscience, 2011: nature.com/articles/nrn3119

[8] Powell v. Texas, 392 U.S. 514 (1968): supreme.justia.com/cases/federal/us/392/514

[9] Binswanger, I.A. et al., "Release from Prison: A High Risk of Death for Former Inmates," New England Journal of Medicine, 2007: nejm.org/doi/full/10.1056/NEJMsa064115

[10] Marlowe, D.B., "Research Update on Adult Drug Courts," National Association of Drug Court Professionals, 2010: nadcp.org