State v. Turgeon, 120 Wash. App. 1050 (2004)
Most states offer an insanity defense to defendants accused of committing a crime, although the nature of that defense varies somewhat from state to state. The State of Washington has adopted the M'Naghten test and will find a defendant legally insane if the defendant can establish that as a result of mental disease or defect the defendant was unable to perceive the nature and quality of the act or was unable to tell the difference between right and wrong with respect to the particular act charged...