The question of whether people with mental disorder should be held accountable for the offences they commit has been an issue that has vexed politicians and public opinion since M'Naughten's Case (1843). Much of the legal terminology relating to the trial and defences that concern perpetrators who have mental disorders hail from the 19th century and continue to apply today.
The debate as to whether people with a mental disorder who commit offences should be punished was again raised when a woman in her mid-seventies who was charged with causing death by careless driving was found not guilty of the offence by reason of insanity. The woman, who had an undiagnosed dementia at the time of the offence, turned her car into the path of a van and the collision forced the van into a woman and child on the pavement. The jury accepted that, as a result of the dementia, the driver did not what she was doing and that it was more than a momentary lapse of concentration. As a result of the special verdict, the judge imposed a 12-month supervision order on the driver (Woodcock, 2022).
During the 1990s and early 2000s government policy focused on diverting people with mental disorders away from the criminal justice system, even at pre-charging and pre-trial stages, to hospital or a suitable community placement for treatment and supervision (Home Office, 1990; Home Office, 1995). Although diversion schemes remain, the decision to prosecute a person with mental disorder for an offence is judged against the threshold test in The Code for Crown Prosecutors (Crown Prosecution Service (CPS), 2019). Where a serious offence has been committed, then prosecution in the public interests in likely to result. The CPS estimates that one in five cases involves a person with a mental disorder.
Legal defence of insanity
When a person with a mental disorder is prosecuted it is open to them to argue that they are not guilty by reason of insanity. This legal defence is available at common law to any criminal charge. For more serious indictable offences in the Crown Court the Trial of Lunatics Act 1883, section 2, provides for a special verdict to be returned by the jury:
‘Where in any indictment or information any act or omission is charged against any person as an offence, and it is given in evidence on the trial of such person for that offence that he was insane, so as not to be responsible, according to law, for his action at the time when the act was done or omission made, then, if it appears to the jury before whom such person is tried that he did the act or made the omission charged, but was insane as aforesaid at the time when he did or made the same, the jury shall return a special verdict that the accused is not guilty by reason of insanity.’
The mere diagnosis or presence of the signs and manifestations of a mental disorder are not enough to meet the requirements of the legal defence of insanity. To be successfully argued it must be shown that at the time of the offence the person was:
- Labouring under such defect of reason due to a disease of the mind as:
- - Not to know the nature and quality of the act being done or,
- - Not to know what was being done was wrong, wrong meaning contrary to the law (M'Naughten's Case (1843)).
Under the rules established in M'Naughten, in order to successfully argue the insanity defence the person must have been suffering from the effects of a mental disorder to the extent that either they did not know what they were doing or that their action would attract the attention of the police. In R v Jones [2007], the Court of Appeal held that a man with paranoid schizophrenia characterised by delusions that people were surrounded by disturbing firewalls was properly convicted of wounding the victim because he knew that his actions were wrong and against the law.
Defect of reason due to a disease of the mind
Uncontrollable urges fall outside the definition of a defect of reason. In R v Kopsch [1927], a man strangled a woman due to an irresistible impulse, but the Court of Appeal rejected his argument that this amounted to insanity.
A disease of the mind must be due to an intrinsic cause, such as sleepwalking, mental disorder, arteriosclerosis or epilepsy. It cannot be due to external causes such as drugs, alcohol or insulin. In R v Sullivan [1984], Sullivan kicked a man in the head and body while suffering an attack of psychomotor epilepsy. He gave evidence that he had no recollection of the incident.
The trial judge ruled that, if the evidence was accepted, the proper verdict was one of not guilty by reason of insanity, whereupon Sullivan changed his plea to one of guilty to assault.
The Court of Appeal held that, although it was regrettable that the label of insanity had to be applied to a case of epilepsy, the judge had been correct in his ruling and not guilty by reason of insanity was the correct verdict.
Whether the defect of reason is permanent or transitory, and whether the disease of the mind results from an organic or functional cause, if it means that the offender is unaware of what he is doing, or that what he is doing is wrong, it is within the M'Naughten Rules and is insanity.
Reaching the special verdict
In the Crown Court only a jury can reach a finding of insanity. In R (London Borough of Harrow) v Maidstone Crown Court [1999] a Crown Court judge found a man not guilty by reason of insanity, without a jury, on a charge of arson based on the unanimous medical evidence. The divisional court held that the judge had acted beyond his authority (ultra vires) because a plea of not guilty by reason of insanity must be followed by a trial of the issue by a jury.
A trial of the issue allows the jury to hear evidence of the person's offences so they are sure the person did the act that led to the charge. The jury must then be satisfied on the balance of probabilities (not the usual beyond a reasonable doubt standard of proof in criminal trials) that the person was insane at the time of the offence. To rebut the presumption that the person is not insane the jury must hear evidence from at least two doctors, one of whom must be approved under section 12 of the Mental Health Act 1983 (Criminal Procedure (insanity and Unfitness to Plead) Act 1991, section 1).
Disposal options available to the court
Where a person has been found not guilty by reason of insanity, the Crown Court has a range of disposal options available under the Criminal Procedure (Insanity) Act 1964, section 5. Depending on evidence from two doctors as to whether the person meets the detention criteria under the Mental Health Act 1983 and the persons risk to public safety, the Crown Court can order
- A hospital order, with or without a restriction,
- A supervision order or
- An order for absolute discharge.
In the magistrates' court, a common law finding of not guilty by reason of insanity means that the person is entitled to be acquitted, although a magistrate can, where appropriate, impose a hospital order without the need to convict the person (Mental Health Act 1983, section 37(3)).
Conclusion
The defence of insanity is available for any offence and in serious cases a jury can reach a special verdict of not guilty by reason of insanity if satisfied, on balance, that the person was legally insane at the time the office took place.
The legal defence of insanity will be successful only if, at the time of the offence, the person did not know what they were doing or did not know that their actions were wrong as a result of their mental disorder.
Being found not guilty by reason of insanity is not the same as a standard acquittal by a court and the judge in a Crown Court has a range of disposal options available to ensure treatment of the person and protection of the public.
KEY POINTS
- The decision to prosecute a person with a mental disorder is made by the Crown Prosecution Service using the threshold test set out in The Code for Crown Prosecutors
- When a person with a mental disorder is charged, they have the defence of insanity available to them, regardless of the offence
- To successfully plead insanity, the person must show that at the time of the offence they were labouring under such defect of reason due to a disease of the mind that they did not know what they were doing or that their actions were wrong
- The court can still impose a range of disposal options, ranging from a hospital order to absolute discharge, depending on the person's need for treatment and public safety, even when the person has been found not guilty by reason of insanity