Also known as: Durham rule · Durham test · product test
Written by attorneys · grounded in primary & secondary sources — see below
A product test for criminal insanity under which a defendant receives an acquittal if the charged offense resulted from a mental disease or defect. An offense qualifies as the product of such a condition when the defendant would not have committed the crime but for the mental disease or defect.
Clifford, a control-room technician with a documented schizo-paranoid disorder, bypassed three safety interlocks while convinced they were government devices designed to cause a blackout. He told investigators immediately afterward that he had acted solely to thwart the conspiracy. The jury credited expert testimony that Clifford would not have bypassed the interlocks absent his fixed delusions.
After an acquittal by reason of insanity, Foucha remained confined because Louisiana law permitted continued detention of insanity acquittees who posed a danger even after they regained sanity. The Supreme Court reviewed whether due process allowed indefinite civil commitment without proof of ongoing mental illness.
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Durham, charged with housebreaking, offered evidence of longstanding mental illness. The D.C. Circuit held that acquittal follows whenever the crime is the product of that illness rather than a separate volitional choice.
Ford, sentenced to death, developed delusions that prison guards were poisoning his food. Florida's procedures for determining sanity for execution were challenged as inadequate to protect his Eighth Amendment interest in avoiding execution while insane.
McDonald, acquitted under the Durham rule, later faced disputes over whether his diagnosed condition qualified as a mental disease or defect. The en banc court clarified that any abnormal mental condition recognized by medical experts could satisfy the threshold.
Powell was convicted of public intoxication despite arguing that his chronic alcoholism constituted a mental disease that produced the offense. The Court examined whether the Durham product test or any other insanity formulation compelled acquittal for status-based conduct.
The defendant must show that the charged offense resulted from a mental disease or defect. This requires proof that the defendant would not have committed the crime but for the mental condition.
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The Durham test focuses solely on causation rather than whether the defendant knew the act was wrong or could conform conduct to the law. A jury may acquit even if the defendant understood the wrongfulness of the act provided the mental disease was the but-for cause.
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Yes. Evidence that the defendant performed the same acts on earlier occasions for non-delusional reasons supports the inference that the mental disease was not the but-for cause of the charged offense.
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Expert testimony that the defendant would not have committed the offense but for the mental disease satisfies the product standard when credited by the fact-finder. The test does not require proof that the disease completely destroyed free will.
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…the hallmark of the procedural protections afforded by the Due Process Clause. See Lassiter v. Department of Social Services of Durham County , 452 U. S. 18, 24-25 (1981). Thus, the question in this case is whether Florida's procedures for determining petitioner's sanity comport with the requirements of due…