Competence to stand trial insanity defense . Our system does not allow prosecution against someone who literally can ' t comprehend what ' s happening . Very rarely is someone incompetent to stand trial and even then competency can be restored on reexamination . Insanity defense comes in different types depending on state . In my state , at least , one can plead insanity if they didn ' t know right from wrong . Given the facts of this scenario , it would be a long shot of a defense . Some insanity defenses require showing that but for the insanity , they would have not committed the act . This is easier to prove , but still unlikely . Edit another important distinctionCompetency to stand trial is about your competency at the time of trial . Insanity defense is about your state of mind during the commission of the act which could be many months prior to the actual trial and such insanity could be nonexistenttreated by the time trial begins . I know these seem like obvious distinctions when explained , but we frequently assume without knowing the legal meaning behind these concepts .