Not Guilty by Reason of Insanity Definition

A plea entered by a defendant in a criminal trial, in which the defendant claims that they were so mentally disturbed or incapacitated at the time of the offense that they could not have intended to commit the crime. A jury that agrees with this plea may find the defendant not guilty by reason of insanity, but usually the defendant faces civil commitment proceedings if the defendant is judged to be dangerous in a subsequent hearing. (See also: insanity defense)