Right and Wrong Test Law and Legal Definition

Right and Wrong Test, also known as McNaghten rules is a test for criminal insanity. This criminal law doctrine says that a person is not criminally responsible for an act when a mental disability prevented the person from knowing either the nature or quality of the act or whether the act was right or wrong. In short, a defendant is legally insane if he/she cannot distinguish between right and wrong in regard to the crime with which he/she is charged. This rule developed in England in the mid-1800s and has been adopted by the U.S courts in some form.