Also known as: product of mental disease or defect · products of mental disease · Durham rule · product test
Written by attorneys · grounded in primary & secondary sources — see below
An offense that results from a mental disease or defect under the Durham insanity test. The offense qualifies as the product when the defendant would not have committed it but for the condition.
Pierce Patterson, a senior engineer, disabled hospital network security and deployed ransomware while suffering psychotic delusions that the servers transmitted mind-control signals. Psychiatrists testified that Patterson would not have launched the attack but for his serious mental disease. In a jurisdiction applying the product test, the jury must acquit because the offense resulted from the disease.
Portia Price, a retail night manager with severe paranoid schizophrenia, set fire to a stockroom after delusions convinced her that merchandise tags contained tracking devices. Experts testified that she would not have committed arson but for the psychotic delusion. Under the product test the jury must acquit because the fire was the direct result of her mental disease.
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Pavel Petrov, an emergency room nurse with severe postpartum psychosis, attacked a pharmaceutical representative after delusions that the visitor was a demon poisoning IV bags. Defense experts testified that but for the psychosis Petrov would not have committed the assault. The product test requires acquittal because the attack resulted from the mental disease.
Pedro Pacheco, a bus driver experiencing auditory hallucinations commanding him to act, veered into a crowded plaza and injured pedestrians. Experts testified that the psychotic disorder caused the deviation and that Pacheco would not have done so but for the disease. The product test compels acquittal because the charged conduct was the result of the mental condition.
The jury must determine whether the defendant would not have committed the crime but for the mental disease or defect. If that but-for causal link is established, the offense is the product of the disease and the defendant must be acquitted.
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No. The product test focuses solely on causation. A defendant may be acquitted even if aware in some abstract sense that the act was wrong, provided the offense would not have occurred but for the mental disease.
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The product test asks only whether the offense resulted from the mental disease in a but-for sense. The irresistible impulse test instead requires proof that the defendant could not control conduct or conform it to the law, regardless of causation.
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Yes. When facts show the defendant would likely have committed the offense even without the mental disease, such as prior similar conduct for rational reasons, the but-for link fails and acquittal is not required.
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…unlike that followed by the New Hampshire court since 1870: an accused is not criminally responsible if his unlawful act was the product of mental disease or mental defect. We use 'disease' to mean a condition capable of improvement or deterioration; 'defect' to mean a more static condition which may be congenital, due to injury, or residual…