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.
Murder is the unlawful killing of another human without justification or valid excuse committed with the necessary intention as defined by the law in a specific jurisdiction. This state of mind may, depending upon the jurisdiction, distinguish murder from other forms of unlawful homicide, such as manslaughter. Manslaughter is killing committed in the absence of malice, such as in the case of voluntary manslaughter brought about by reasonable provocation, or diminished capacity. Involuntary manslaughter, where it is recognized, is a killing that lacks all but the most attenuated guilty intent, recklessness.
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 law, provocation is when a person is considered to have committed a criminal act partly because of a preceding set of events that might cause a reasonable individual to lose self control. This makes them less morally culpable than if the act was premeditated (pre-planned) and done out of pure malice. It "affects the quality of the actor's state of mind as an indicator of moral blameworthiness."
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.
"Twinkie defense" is a derisive label for an improbable legal defense. It is not a recognized legal defense in jurisprudence, but a catch-all term coined by reporters during their coverage of the trial of defendant Dan White for the murders of San Francisco city Supervisor Harvey Milk and Mayor George Moscone. White's defense was that he suffered diminished capacity as a result of his depression, a symptom of which was a change in diet from healthy food to Twinkies and other sugary foods. Contrary to common belief, White's attorneys did not argue that the Twinkies were the cause of White's actions, but that their consumption was symptomatic of his underlying depression. The product itself was only mentioned in passing during the trial. White was convicted of voluntary manslaughter rather than first-degree murder, and served five years in prison.
The Infanticide Act is the name of two 20th-century acts in English law that started treating the killing of an infant child by its mother during the early months of life as a lesser crime than murder.
Battered woman syndrome (BWS) is a pattern of signs and symptoms displayed by a woman who has suffered persistent intimate partner violence—psychological, physical, or sexual—from her male partner. It is classified in the ICD-9 as battered person syndrome, but is not in the DSM-5. It may be diagnosed as a subcategory of post-traumatic stress disorder (PTSD). Victims may exhibit a range of behaviors, including self-isolation, suicidal thoughts, and substance abuse, and signs of physical injury or illness, such as bruises, broken bones, or chronic fatigue.
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.
The Homicide Act 1957 is an Act of the Parliament of the United Kingdom. It was enacted as a partial reform of the common law offence of murder in English law by abolishing the doctrine of constructive malice, reforming the partial defence of provocation, and by introducing the partial defences of diminished responsibility and suicide pact. It restricted the use of the death penalty for murder.
In English law, diminished responsibility is one of the partial defenses that reduce the offense from murder to manslaughter if successful. This allows the judge sentencing discretion, e.g. to impose a hospital order under section 37 of the Mental Health Act 1983 to ensure treatment rather than punishment in appropriate cases. Thus, when the actus reus of death is accompanied by an objective or constructive version of mens rea, the subjective evidence that the defendant did intend to kill or cause grievous bodily harm because of a mental incapacity will partially excuse his conduct. Under s.2(2) of the Homicide Act 1957 the burden of proof is on the defendant to the balance of probabilities. The M'Naghten Rules lack a volitional limb of "irresistible impulse"; diminished responsibility is the volitional mental condition defense in English criminal law.
In the English law of homicide, manslaughter is a less serious offence than murder, the differential being between levels of fault based on the mens rea or by reason of a partial defence. In England and Wales, a common practice is to prefer a charge of murder, with the judge or defence able to introduce manslaughter as an option. The jury then decides whether the defendant is guilty or not guilty of either murder or manslaughter. On conviction for manslaughter, sentencing is at the judge's discretion, whereas a sentence of life imprisonment is mandatory on conviction for murder. Manslaughter may be either voluntary or involuntary, depending on whether the accused has the required mens rea for murder.
Manslaughter is a common law legal term for homicide considered by law as less culpable than murder. The distinction between murder and manslaughter is sometimes said to have first been made by the ancient Athenian lawmaker Draco in the 7th century BC.
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.
Fault, as a legal term, refers to legal blameworthiness and responsibility in each area of law. It refers to both the actus reus and the mental state of the defendant. The basic principle is that a defendant should be able to contemplate the harm that his actions may cause, and therefore should aim to avoid such actions. Different forms of liability employ different notions of fault, in some there is no need to prove fault, but the absence of it.
Insanity in English law is a defence to criminal charges based on the idea that the defendant was unable to understand what he was doing, or, that he was unable to understand that what he was doing was wrong.
English law contains homicide offences – those acts involving the death of another person. For a crime to be considered homicide, it must take place after the victim's legally recognised birth, and before their legal death. There is also the usually uncontroversial requirement that the victim be under the "King's peace". The death must be causally linked to the actions of the defendant. Since the abolition of the year and a day rule, there is no maximum time period between any act being committed and the victim's death, so long as the former caused the latter.
Manslaughter is a crime in the United States. Definitions can vary among jurisdictions, but manslaughter is invariably the act of causing the death of another person in a manner less culpable than murder. Three types of unlawful killings constitute manslaughter. First, there is voluntary manslaughter which is an intentional homicide committed in "sudden heat of passion" as the result of adequate provocation. Second, there is the form of involuntary manslaughter which is an unintentional homicide that was committed in a criminally negligent manner. Finally, there is the form of involuntary manslaughter which is an unintentional homicide that occurred during the commission or attempted commission of an unlawful act which does not amount to a felony.
