Insanity Defense - Scottish Law

Scottish Law

The Scottish Law Commission, in its Discussion Paper No 122 on Insanity and Diminished Responsibility (2003), pp. 16/18 confirms that the law has not substantially changed from the position stated in Hume's Commentaries:

We may next attend to the case of those unfortunate persons, who have plead the miserable defense of idiocy or insanity. Which condition, if it is not an assumed or imperfect, but a genuine and thorough insanity, and is proved by the testimony of intelligent witnesses, makes the act like that of an infant, and equally bestows the privilege of an entire exemption from any manner of pain; Cum alterum innocentia concilii tuetur, alterum fati infelicitas excusat. I say, where the insanity is absolute, and is duly proved: For if reason and humanity enforce the plea in these circumstances, it is no less necessary to observe a caution and reserve in applying the law, as shall hinder it from being understood, that there is any privilege in a case of mere weakness of intellect, or a strange and moody humor, or a crazy and capricious or irritable temper. In none of these situations does or can the law excuse the offender. Because such constitutions are not exclusive of a competent understanding of the true state of the circumstances in which the deed is done, nor of the subsistence of some steady and evil passion, grounded in those circumstances, and directed to a certain object. To serve the purpose of a defense in law, the disorder must therefore amount to an absolute alienation of reason, ut continua mentis alienatione, omni intellectu careat - such a disease as deprives the patient of the knowledge of the true aspect and position of things about him - hinders him from distinguishing friend from foe - and gives him up to the impulse of his own distempered fancy.

The phrase "absolute alienation of reason" is still regarded as at the core of the defense in the modern law (see HM Advocate v Kidd (1960) JC 61 and Brennan v HM Advocate (1977)