Also known as: temporarily insane · insanity defense · temporary mental incapacity
Written by attorneys · grounded in primary & secondary sources — see below
A variant of the insanity defense under which a defendant is excused from criminal liability because a mental disease or defect caused a lack of substantial capacity to appreciate the wrongfulness of conduct or to conform conduct to law solely at the time of the offense.
Tyler Taylor was arrested for assault after a sudden outburst at work. He received Miranda warnings and remained silent during questioning. At trial he raised temporary insanity based on a brief manic episode. The prosecution sought to introduce his post-warning silence to suggest the defense was fabricated. The court barred that use of the silence.
Tristan Thompson was charged with arson after setting a controlled burn that escaped during a claimed dissociative episode. His counsel filed written notice of a temporary insanity defense weeks after the pretrial motion deadline. The government objected. The court refused to allow the defense because the notice was untimely and no good cause was shown.
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Tanya Tang shot a perceived intruder during an acute psychotic break triggered by medication withdrawal. Expert testimony established that the delusion existed only at the instant of the act and had resolved by the time of arrest. The court permitted the temporary insanity defense and the jury acquitted.
Tyrone Tran faced murder charges after a frenzied attack during a documented manic episode. He made a preliminary showing that temporary insanity would be raised. The trial court denied funds for a defense psychiatrist. The appellate court reversed, holding that the state must provide the expert to prepare the defense.
Travis Tate was acquitted by reason of temporary insanity after a brief psychotic episode led to an assault. The state sought civil commitment based on dangerousness shown at sentencing. The court upheld the commitment proceeding because the acquittal did not preclude future dangerousness findings.
Thaddeus Tran was convicted of capital murder after a rage-fueled killing during an undiagnosed manic episode. At the penalty phase he offered psychiatric testimony that the episode caused temporary inability to appreciate wrongfulness. The court admitted the evidence as mitigation supporting a life sentence.
Temporary insanity is not a formally distinct defense. It simply requires proof that the mental disease or defect existed only at the time of the offense and had resolved by trial, allowing acquittal without automatic commitment for ongoing treatment.
In some jurisdictions evidence of voluntary intoxication may be admitted to show temporary insanity that mitigates punishment even though it does not excuse the underlying offense.
Under Federal Rule of Criminal Procedure 12.2(a) a defendant must file written notice of an insanity defense within the time for pretrial motions or at a later time set by the court. Failure to give timely notice bars reliance on the defense absent good cause.
No. Using post-Miranda silence to rebut an insanity defense violates the implicit assurance that silence carries no penalty.
…was ratified. Commonwealth v. York , 50 Mass. 93 (1845).[^maj-8] In 1895 the common-law view was abandoned with respect to the insanity defense in federal prosecutions. Davis v. United States , 160 U. S. 469 (1895). This ruling had wide impact on the practice in the federal courts with respect to the burden of proving various…