What is the difference between insanity and mental illness?  How might this distinction affect a forensic evaluation?

Insanity is a legal term with its modern roots in the M'Naghten ruling in 1843. This has been revised several times (Durham v. United States, 1954; The ALI Standard, 1962; Insanity Defense Reform Act, 1984).

Mental illness is a clinical term based upon diagnostic criteria usually set forth in the DSM-IV.  An individual may be mentally ill but not legally insane. However, an individual cannot be insane without suffering from a mental disease or defect.


BACK