Also known as:Durham Product Test · Durham test · Durham rule · product test · Durham insanity test · product rule
Written by attorneys · grounded in primary & secondary sources — see below
A 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 the condition when the defendant would not have committed the crime but for the mental disease or defect.
Sources & Authorities
How it applies
Common Examples
2
Delusional Contamination of Medication
Dylan Duffy, a research chemist with severe schizoaffective disorder featuring delusions of mind-control conspiracies, contaminated a clinical trial batch with household cleaner after believing management had ordered a dangerous additive. He immediately told investigators that the cleaner would neutralize the threat to participants. Expert testimony confirmed the disorder generated fixed false beliefs that directly motivated the precise conduct. Under the product test the jury must acquit because the offense would not have occurred but for the mental disease.
Paranoid Bypass of Safety Interlocks
Demetrius Douglas, a nuclear facility technician with documented schizo-paranoid disorder, bypassed three redundant cooling-system interlocks while experiencing active delusions that federal agents had installed them to cause a blackout. He told investigators immediately afterward that the interlocks formed part of the conspiracy. Although he had bypassed identical interlocks on prior occasions for production reasons, the current conduct aligned directly with the content of the delusions. The product test requires acquittal if the jury finds the offense would not have taken place but for the mental disease.
Select any source to read its text and confirm it supports the definition.
Common Law
Casebooks
Study Supplements
Blocker v. U.S.274 F.2d 572 (D.C.Cir.1959)
Common questions
Frequently Asked
4
What must the prosecution prove to defeat a Durham product defense?+
The prosecution must prove beyond a reasonable doubt either that the defendant lacked a mental disease or defect or that the offense was not the product of any such condition. The but-for causation inquiry examines all evidence of motive, timing, planning, and statements to determine whether the defendant would have committed the offense even without the illness.
Supporting sources
Does evidence of an independent rational motive automatically defeat the Durham product test?+
No. The test turns on whether the offense would have occurred but for the mental disease or defect. When evidence shows both a delusional motive and a separate rational motive, the jury must decide which inference is stronger based on the full record, including timing, prior conduct, and expert testimony.
Supporting sources
How does the Durham product test differ from the irresistible impulse test?+
The product test focuses solely on causation in fact between the mental disease and the offense. The irresistible impulse test instead asks whether mental illness deprived the defendant of the ability to control conduct or conform it to the law, regardless of whether the illness originated the criminal idea.
Supporting sources
Can the product test apply to nonviolent financial crimes?+
Yes. The test applies to any criminal offense whenever the mental disease or defect is the but-for cause of the conduct. A manic episode producing grandiose delusions that lead to fraudulent endorsements satisfies the standard if the jury finds the illness supplied the necessary impetus.
Supporting sources
823 P.2d 128 (Colo. 1992)Criminal Law
…(adopting modern “product”test). But see United States v. Brawner , 471 F.2d 969 (D.C.Cir.1972) (abandoning Durham product test and adopting ALI-MPC test).[^disA-2] In Colorado, the test of criminal responsibility, which has been codified in section 16-8-101(1), is the “right from wrong” prong of the test announced…