Prescription amphetamines, psychosis, and criminal responsibility: what United States v. Rainford illustrates

In United States v. Rainford, a federal murder case arising from a 2021 shooting in Oklahoma, the defendant had been prescribed unusually high doses of Adderall before developing persecutory delusions about his neighbor. A Bureau of Prisons psychologist concluded that he had amphetamine-induced psychosis and was legally insane at the time of the shooting because of involuntary intoxication. The jury rejected that defense and convicted him of first-degree murder. In December 2025, the Tenth Circuit reversed the conviction because the jury had been given legally erroneous instructions about involuntary intoxication.

The case highlights a difficult intersection between psychiatry and criminal law. A defendant may voluntarily consume one substance while also taking prescribed medication. A prescribed medication may itself produce an unexpected psychiatric reaction. In other cases, medication may amplify or alter the effects of alcohol or another drug in a way the person did not anticipate.

Those situations can raise questions that are quite different from ordinary voluntary intoxication. The terminology and legal consequences of intoxication vary by jurisdiction, and the psychiatric questions do not themselves determine whether a particular defense is legally available.

In our 2021 article, “Voluntary Intoxication, Homicide, and Mens Rea: Past, Present, and Future”, my coauthors and I reviewed the substantial variation among jurisdictions in how voluntary intoxication may affect the prosecution's proof of mens rea. Depending on the jurisdiction, intoxication evidence may sometimes bear on whether a defendant formed the mental state required for a particular offense, even though voluntary intoxication itself generally does not establish legal insanity.

When Prescription Medication Changes the Intoxication Question

Voluntary intoxication may appear relatively straightforward conceptually: a person knowingly consumes an intoxicating substance and later argues that the intoxication affected his mental state. Prescription medication can make the analysis considerably more complicated.

A defendant may take a medication exactly as prescribed and experience an unexpected adverse psychiatric effect. A medication may produce psychosis, mania, delirium, or another significant change in mental state. A defendant may also voluntarily consume alcohol or an illicit substance while taking prescribed medication and experience effects that are substantially different from what either substance would ordinarily produce alone.

That can create a more complex analysis. Rather than identifying whether the defendant voluntarily consumed something intoxicating, there may be questions involving whether the resulting psychiatric condition was reasonably foreseeable, whether prescribed medication caused or materially contributed to it, and whether an unexpected interaction changed the nature or severity of the intoxication.

Rainford illustrates the problem directly. The defense evidence attributed Rainford's psychosis to prescribed Adderall. There was also evidence concerning possible methamphetamine use. The Tenth Circuit emphasized that illegal drug use could be relevant to the analysis, but it could not automatically defeat the involuntary-intoxication defense without considering causation. The relevant question was which substance, or combination of substances, caused the mental condition at issue.

Intoxication and Substance-Induced Psychosis Are Different Clinical Phenomena

Acute intoxication can produce impaired judgment, disinhibition, confusion, perceptual changes, agitation, and other behavioral effects.

Substance-induced psychosis may involve hallucinations, delusions, or other psychotic symptoms attributable to a substance or medication. Depending on the substance and the individual, those symptoms may persist beyond the period of obvious intoxication.

A defendant who drank heavily and became impulsive presents a different psychiatric picture from someone who developed sustained paranoid delusions after exposure to a stimulant. Both situations involve substances, but the effect on mental functioning may be very different.

Furthermore, a substance-induced psychiatric disorder may affect perception of reality in ways that ordinary intoxication does not.

What Did the Defendant Know and What Was Foreseeable?

One of the most interesting aspects of Rainford involved what the defendant knew about Adderall's possible effects.

The trial court instructed the jury that Rainford could not be involuntarily intoxicated if he knew that Adderall could have intoxicating effects. The Tenth Circuit rejected that categorical approach. Knowledge of possible effects could be relevant, but it did not automatically resolve whether Rainford's actual psychiatric reaction was reasonably foreseeable.

For example, a patient may know that a medication can cause insomnia, anxiety, or appetite suppression without reasonably anticipating severe persecutory delusions. Likewise, someone may understand that drinking alcohol while taking a medication is discouraged without necessarily anticipating an extreme psychiatric reaction from the combination.

Relevant considerations can include what the defendant was told, prior effects, the dose involved, the timing of symptoms, other substances being used, and whether the psychiatric reaction was reasonably foreseeable.

Voluntary Intoxication Can Be Complicated by Prescription Medication

There is also an important middle ground between ordinary voluntary intoxication and a purely involuntary reaction to prescribed medication.

Suppose a defendant voluntarily drinks alcohol while taking a prescribed medication. The alcohol use is clearly voluntary. But the medication unexpectedly amplifies the effect of the alcohol or contributes to a psychiatric reaction that is far more severe than the person has experienced previously.

Or suppose a defendant voluntarily uses a stimulant but is also taking another medication that substantially alters its effects.

These cases do not fit neatly into a simple voluntary-versus-involuntary framework.

The legal significance will depend on the jurisdiction, while causation may become an important part of the psychiatric analysis. Relevant questions can include which substance contributed to the mental state, whether the medication independently caused symptoms, whether the substances interacted, whether the resulting effects were foreseeable, and whether the defendant was experiencing ordinary intoxication, a substance-induced psychiatric disorder, or both.

The answers may affect how the psychiatric evidence relates to mens rea, criminal responsibility, or another legal issue.

The Timeline Becomes Critical

Substance-related forensic evaluations often depend heavily on chronology.

The chronology may include when each substance or medication was taken, when symptoms began, whether psychotic symptoms persisted after intoxication should have resolved, whether similar episodes occurred during periods of sobriety, and whether psychiatric symptoms existed before the substance exposure.

Toxicology can help, but it does not answer every question. A positive test establishes exposure, not necessarily the degree of intoxication at an earlier moment or the psychiatric effect produced in that particular person. Conversely, a negative toxicology result does not necessarily establish that the person had not previously used the substance. Detection windows vary, and psychiatric effects triggered by an earlier ingestion may persist after the substance is no longer detectable.

Treatment records, prescription records, pharmacy data, witness accounts, electronic communications, police observations, and behavior before and after the offense may therefore become particularly important.

In Rainford, contemporaneous observations were relevant because witnesses and police described unusual behavior around the time of the shooting, while the expert testimony addressed whether the prescribed amphetamine had produced psychosis.

Criminal Responsibility and Mens Rea Still Need to Be Kept Separate

Substance-related psychiatric cases can become confusing because several legal concepts may be discussed at once.

Legal insanity asks whether a mental condition affected capacities defined by the jurisdiction's insanity standard. Mens rea asks whether the prosecution has established the mental state required for the charged offense.

Intoxication defenses may interact with either question, but the rules vary by jurisdiction.

As described in our paper, some jurisdictions allow intoxication evidence to negate certain forms of specific intent, while others restrict or prohibit its use more broadly.

For the psychiatrist, the important point is that the clinical diagnosis does not answer the legal question by itself. The psychiatrist may conclude that a defendant was intoxicated, psychotic, or experiencing a substance-induced disorder. The next question is what that condition actually changed about perception, judgment, intent, appreciation of wrongfulness, or another capacity relevant to the law.

Why Rainford Matters

Rainford is important because it shows how quickly substance-related criminal cases can become more complicated than the phrase "voluntary intoxication" suggests.

A defendant may be taking prescribed medication. There may be unexpected psychiatric effects. Other substances may also be involved. The resulting mental state may reflect intoxication, a medication-induced psychiatric disorder, an interaction among substances, or an underlying psychiatric illness.

The appellate court did not decide that Rainford was legally insane. It held that the jury had been instructed incorrectly about how to evaluate his involuntary-intoxication defense and reversed the conviction for a new trial.

Forensic psychiatry can be particularly useful in these cases because the clinical task is often one of reconstruction and causation. The evaluation may therefore examine what substances and medications were present, what psychiatric condition developed, how the timing fits together, what effects were reasonably foreseeable, and what the resulting mental state meant.

Disclaimer: This article is provided for general educational and informational purposes only and reflects discussion of forensic psychiatric issues, not legal or medical advice. The significance of psychiatric evidence depends on the facts of the individual case, the applicable legal standard, and the information available for review. Any forensic psychiatric opinion should be understood only in the context of the specific evaluation in which it is offered. Legal questions should be addressed by qualified counsel.