As opposed to the all-or-none insanity defense, mens rea defense permits gradations of guilt but is generally inapplicable unless elements of a crime are redefined to permit consideration of motivational aspects. California's change from a diminished capacity defense to a diminished actuality defense represents a return to the complex, somewhat artificial legal concept of intent and a resurrection of confusing and antiquated common law definitions. The change was made in response to an unpopular jury verdict and a political climate in which little interest existed for understanding reasons behind the commission of a crime. The authors point out that some of the later restrictions imposed by the California Supreme Court on allowing voluntary intoxication to reduce murder to voluntary manslaughter should not apply to mental illness. They also indicate that knowledge of complex mens rea issues and relevant defenses is essential for any forensic psychiatrist who evaluates defendants in jurisdictions where such defenses are admissible. 55 references