M'Naghten's Case
The M'Naghten Rules: the test for the defence of insanity.
Facts
Daniel M'Naghten suffered from delusions that he was being persecuted by the Tory party. He tried to kill the Prime Minister, Sir Robert Peel, but shot and killed Peel's secretary, Edward Drummond, by mistake. He was acquitted of murder on the ground of insanity, which caused a public outcry. The House of Lords asked the judges a series of questions about the law of insanity.
Legal principle
The judges' answers, known as the M'Naghten Rules, state that everyone is presumed to be sane, and that to establish a defence on the ground of insanity, it must be clearly proved that, at the time of committing the act, the accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing, or, if he did know it, that he did not know he was doing what was wrong. The Rules still define the defence of insanity in English law.
Related cases on defences: insanity, automatism and intoxication
- Attorney General for Northern Ireland v Gallagher [1963] AC 349
- Attorney General's Reference (No 2 of 1992) [1994] QB 91
- DPP v Majewski [1977] AC 443
- Hill v Baxter [1958] 1 QB 277
- R v Bailey [1983] 1 WLR 760
- R v Burgess [1991] 2 QB 92
- R v Coley; R v McGhee; R v Harris [2013] EWCA Crim 223
- R v Hardie [1985] 1 WLR 64
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This summary is for study and revision and is not legal advice. Although our case summaries are checked for accuracy, we do not guarantee that they are free from errors or omissions. Always read the full judgment for the court's reasoning.
