The insanity defense, also known as the mental disorder defense, is an affirmative defense by excuse in a criminal case, arguing that the defendant is not responsible for their actions due to a psychiatric disease at the time of the criminal act. This is contrasted with an excuse of provocation, in which the defendant is responsible, but the responsibility is lessened due to a temporary mental state. It is also contrasted with the justification of self defense or with the mitigation of imperfect self-defense. The insanity defense is also contrasted with a finding that a defendant cannot stand trial in a criminal case because a mental disease prevents them from effectively assisting counsel, from a civil finding in trusts and estates where a will is nullified because it was made when a mental disorder prevented a testator from recognizing the natural objects of their bounty, and from involuntary civil commitment to a mental institution, when anyone is found to be gravely disabled or to be a danger to themself or to others.
The M'Naghten rule(s) (pronounced, and sometimes spelled, McNaughton) is a legal test defining the defence of insanity, first formulated by the House of Lords in 1843. It is the established standard in UK criminal law. Versions have been adopted in some US states, currently or formerly, and other jurisdictions, either as case law or by statute. Its original wording is a proposed jury instruction:
that every man is to be 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 the committing of the act, the party 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.
In criminal law, diminished responsibility is a potential defense by excuse by which defendants argue that although they broke the law, they should not be held fully criminally liable for doing so, as their mental functions were "diminished" or impaired.
In criminal law, irresistible impulse is a defense by excuse, in this case some sort of insanity, in which the defendant argues that they should not be held criminally liable for their actions that broke the law, because they could not control those actions, even if they knew them to be wrong. It was added to the M'Naghten rule as a basis for acquittal in the mid 20th century.
Daniel M'Naghten was a Scottish woodturner who assassinated English civil servant Edward Drummond while suffering from paranoid delusions. Following his trial and its aftermath, his name has been given to the legal test of criminal insanity in England and other common law jurisdictions known as the M'Naghten rules.
In criminal law, automatism is a rarely used criminal defence. It is one of the mental condition defences that relate to the mental state of the defendant. Automatism can be seen variously as lack of voluntariness, lack of culpability (unconsciousness) or excuse. Automatism means that the defendant was not aware of his or her actions when making the particular movements that constituted the illegal act.
Edward Oxford was an English man who attempted to assassinate Queen Victoria in 1840. He was the first of seven unconnected people who tried to kill her between 1840 and 1882. Born and raised in Birmingham, he showed erratic behaviour which was sometimes threatening or violent. He had a series of jobs in pubs, all of which he lost because of his conduct. In 1840, shortly after being dismissed from yet another pub, he purchased two pistols and fired twice at Queen Victoria and her husband, Prince Albert. No-one was hurt.
James Hadfield or Hatfield attempted to assassinate George III of Great Britain in 1800 but was acquitted of attempted murder by reason of insanity.
The Criminal Lunatics Act 1800 was an Act of the Parliament of Great Britain that required and established a set procedure for the indefinite detention of mentally ill offenders. It was passed through the House of Commons in direct reaction to the trial of James Hadfield, who attempted to assassinate King George III.
Clark v. Arizona, 548 U.S. 735 (2006), is a United States Supreme Court case in which the Court upheld the constitutionality of the insanity defense used by Arizona.
Bratty v Attorney-General for Northern Ireland [1963] AC 386, [1961] 3 All ER 523, [1961] UKHL 3 is a House of Lords decision relating to non-insane automatism. The court decided that medical evidence is needed to prove that the defendant was not aware of what they were doing, and if this is available, the burden of proof lies with the prosecution to prove that intention was present.
English criminal law concerns offences, their prevention and the consequences, in England and Wales. Criminal conduct is considered to be a wrong against the whole of a community, rather than just the private individuals affected. The state, in addition to certain international organisations, has responsibility for crime prevention, for bringing the culprits to justice, and for dealing with convicted offenders. The police, the criminal courts and prisons are all publicly funded services, though the main focus of criminal law concerns the role of the courts, how they apply criminal statutes and common law, and why some forms of behaviour are considered criminal. The fundamentals of a crime are a guilty act and a guilty mental state. The traditional view is that moral culpability requires that a defendant should have recognised or intended that they were acting wrongly, although in modern regulation a large number of offences relating to road traffic, environmental damage, financial services and corporations, create strict liability that can be proven simply by the guilty act.
Settled insanity is defined as a permanent or "settled" condition caused by long-term substance abuse and differs from the temporary state of intoxication. In some United States jurisdictions "settled insanity" can be used as a basis for an insanity defense, even though voluntary intoxication cannot, if the "settled insanity" negates one of the required elements of the crime such as malice aforethought. However, U.S. federal and state courts have differed in their interpretations of when the use of "settled insanity" is acceptable as an insanity defense and also over what is included in the concept of "settled insanity".
In the field of criminal law, there are a variety of conditions that will tend to negate elements of a crime, known as defenses. The label may be apt in jurisdictions where the accused may be assigned some burden before a tribunal. However, in many jurisdictions, the entire burden to prove a crime is on the prosecution, which also must prove the absence of these defenses, where implicated. In other words, in many jurisdictions the absence of these so-called defenses is treated as an element of the crime. So-called defenses may provide partial or total refuge from punishment.
The Trial of Lunatics Act 1883 is an act of the Parliament of the United Kingdom, allowing the jury to return a verdict that the defendant was guilty, but insane at the time, and should be kept in custody as a "criminal lunatic". This act was passed at the request of Queen Victoria, who, the target of frequent attacks by mentally ill individuals, demanded that the verdict be changed from "not guilty" so as to act as a deterrent to other lunatics; the phrasing of "guilty of the act or omission charged, but insane so as not to be responsible, according to law, for his actions" remained in use until the Criminal Procedure (Insanity) Act 1964.
In Rex v Bourke, an important case in South African criminal law, the Transvaal Provincial Division (TPD) held that, under Roman-Dutch law, drunkenness is, as a general rule, no defence to a crime, although it may be a reason for mitigation of punishment. If the drunkenness is not voluntary—that is, if not caused by an act of the accused—and results in rendering the accused unconscious of what he was doing, he would not be responsible in law for an act done while in such a state. If constant drunkenness has induced a state of mental disease rendering the accused unconscious of his act at the time, he is not responsible and can be declared insane. Where a special intention is necessary to constitute a particular offence, drunkenness might reduce the crime from a more serious to a less serious one.
People v Schmidt, 216 N.Y. 324 (1915), is a criminal case interpreting "wrong" in the M'Naghten rule for an insanity defense.
The Royal Commission on Capital Punishment 1949–1953 reviewed the application of death penalty in the United Kingdom, including the questions of what crimes should receive the death penalty and what method of execution should be employed. The commission was set up by the Attlee government in an attempt to defuse the long-term political debate over capital punishment. The Royal Warrant establishing the commission instructed their inquiry to assume the retention of the death penalty. In their report, the Commission described their own task as "trying to find some practical half-way house between the present scope of the death penalty and its abolition"
The ALI rule, or American Law Institute Model Penal Code rule, is a recommended rule for instructing juries how to find a defendant in a criminal trial is not guilty by reason of insanity. It broadened the M'Naghten rule of whether a defendant was so mentally ill that he is unable to "know" the nature and quality of his criminal act, or know its wrongfulness, to a question of whether he had "substantial capacity to appreciate the criminality of [his] conduct". It also added a volitional component as to whether defendant was lacking in "substantial capacity to conform his conduct to the law". It arose from the case of United States v. Brawner.
Kahler v. Kansas, 589 U.S. ___ (2020), is a case of the United States Supreme Court in which the justices ruled that the Eighth and Fourteenth Amendments of the United States Constitution do not require that states adopt the insanity defense in criminal cases that are based on the defendant's ability to recognize right from wrong. It was argued on October 7, 2019 and decided on March 23, 2020.
