R v Codere (1916) 12 Cr App R 21
Defence of insanity not applicable where accused aware of the nature and quality of actions
Facts
C appealed against his conviction for murder. At trial, expert witnesses had disagreed on whether he could be certified as insane.
Issues
According to the “M’Naghtenrules” (see R v McNaughten 8 E.R. 718) an insanity defence requires proof that the accused did not appreciate “nature and quality” of the act committed or, did not know what he was doing was wrong. Therefore, if it is clear that the accused was aware that the act was wrong and contrary to the law of the land then he is liable to be punished. On appeal, counsel for C argued that C’s conduct before and after the murder, as narrated by various witnesses, pointed to the conclusion that he was not aware that the act was wrong. As C was incapable of understanding the heinousness of his actions it was argued that the defence of insanity should apply.
Decision/Outcome
The Court considered the meaning of the words “nature and quality” in the M’Naghten rules and held that the Court in that case did not intend to distinguish between the physical and moral aspects of the act. If C understood the physical nature of the act it then ought to be considered whether he knew it was wrong. If he was aware that the act was wrong in law then he could be considered aware that he ought not to do it. On the available evidence, the Court held that whilst it was clear that C was “abnormal mentally” there was sufficient evidence that he was conscious that the act was wrong and contrary to law. The appeal was accordingly dismissed.
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Updated 20 March 2026
This case summary remains accurate. R v Codere (1916) 12 Cr App R 21 is a valid reported decision of the Court of Criminal Appeal and the legal principles described are correctly stated. The M’Naghten rules, as established in R v McNaughten (1843) 8 ER 718, remain the governing common law test for the defence of insanity in England and Wales. The two-limb test — whether the defendant did not know the nature and quality of the act, or did not know it was wrong — continues to apply. Codere is still cited as authority for the proposition that “nature and quality” in the first limb refers to the physical nature of the act, not its moral character, and that awareness of legal wrongdoing suffices under the second limb.
Readers should be aware, however, that the insanity defence and the M’Naghten rules have been the subject of ongoing law reform debate. The Law Commission considered reform of the defence in its 2013 Discussion Paper and subsequent work, but as of the date of this update no statutory reform has been enacted. The rules therefore remain in their historic common law form. The Criminal Procedure (Insanity) Act 1964 and the Criminal Procedure (Insanity and Unfitness to Plead) Act 1991 govern procedural aspects, including the special verdict of not guilty by reason of insanity, but do not alter the substantive M’Naghten test itself. This article is suitable for use as a case summary of the substantive law.
