Crown v. M'Naghten

Crown v. M'Naghten (1843) is a landmark legal case that established the "insanity defense" in criminal law. The case involved Daniel M'Naghten, who believed the Prime Minister was trying to harm him and, in a misguided attempt to protect himself, killed the Prime Minister’s secretary. The court decided that M'Naghten did not understand the nature of his actions or that they were wrong due to his mental illness. This case set the standard for determining criminal responsibility based on whether a defendant had a mental state that impaired their understanding or control at the time of the crime.