Understanding the Insanity Defense (National Overview)

This lecture describes the history and practical uses of the insanity defense in the United States. The insanity defense has always been unpopular and controversial, and many violent offenders are convicted in spite of, and even because of, severe mental illness. The lecture describes the essential paradox of the insanity defense: more evidence of insanity tends to establish greater danger, and leads to convictions even in cases where defendants meet the legal definition of insanity. The lecture describes the development of the insanity defense in the United States, including the M'Naghton and  "irresistible impulse" tests, the "Durham" test experiment, and the national evisceration of insanity defenses following the acquittal of John Hinkley, Jr. Lastly, the lecture describes the practical problems of the insanity defense, including diagnosis of mental illness, prior histories and law testimony, evidence of planning and flight, the relationship between insanity and other defenses, the consequences of an NGRI verdict, jury instructions and closing argument.

Learning Objectives: 

1. Review the major differences between jurisdictions as to the different "tests" for insanity
2. Understand the practical problems of presenting justification defenses, including strategy, tactics, instructions, and typical evidentiary issues