(a) In any prosecution for an offense, it shall be an affirmative defense that the defendant, at the time the defendant committed the proscribed act or acts, lacked substantial capacity, as a result of mental disease or defect, either to appreciate the wrongfulness of his conduct or to control his conduct within the requirements of the law.

Have a question?
Click here to chat with a criminal defense lawyer and protect your rights.

(b) (1) It shall not be a defense under this section if such mental disease or defect was proximately caused by the voluntary ingestion, inhalation or injection of intoxicating liquor or any drug or substance, or any combination thereof, unless such drug was prescribed for the defendant by a prescribing practitioner, as defined in subdivision (28) of § 20-571, and was used in accordance with the directions of such prescription.

(2) No defendant may claim as a defense under this section that such mental disease or defect was based solely on the discovery of, knowledge about or potential disclosure of the victim’s actual or perceived sex, sexual orientation or gender identity or expression, including under circumstances in which the victim made an unwanted, nonforcible, romantic or sexual advance toward the defendant, or if the defendant and victim dated or had a romantic relationship.

(c) As used in this section, (1) the terms mental disease or defect do not include (A) an abnormality manifested only by repeated criminal or otherwise antisocial conduct, or (B) pathological or compulsive gambling, and (2) “gender identity or expression” means gender identity or expression, as defined in § 53a-181i.