The authors outline some of the problems involved in making a determination of legal insanity when a crime is committed following the use of LSD. Three cases of murder known to be associated with the use of LSD are described, one of them involving an individual examined personally by the authors. Five specific criteria that the authors have found to be useful aids in forensic examinations of such cases are offered. Finally, the differences between alcoholic intoxication and LSD-induced psychosis are discussed to help clarify the issue of voluntary intoxication in regard to criminal responsibility.Abstract Teaser