durham rule n[from Durham v. United States , 214 F.2d 862 (1954), a case heard by the District of Columbia Court of Appeals that established the rule]
: a rule of criminal law used in some states that holds that in order to find a defendant not guilty by reason of insanity the defendant's criminal act must be the product of a mental disease or defect compare irresistible impulse test , m'naghten test , substantial capacity test
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.