Diminished Responsibility Law and Legal Definition

Diminished responsibility is a defense sometimes offered in criminal cases that refers to a condition of arrested or retarded development of mind, whether inherent or caused by disease or injury, that substantially impairs a person's mental responsibility for his/her acts or omissions. It is also referred to as diminished capacity.

The diminished capacity plea is based in the belief that certain people, because of mental impairment or disease, are simply incapable of possessing the mental state required to commit a certain crime. If diminished responsibility is proven, it may negate an element of the crime, such as premediation, with which a defendant is charged, so that the defendant can be convicted only of a lesser offense. It differs from an insanity plea, because unlike the successful insanty defense, a defendant will not be found not guilty, but will instead be subject to a lesser charge.