post on the Salomons blog questions whether we need the idea of mental illness in criminal justice. He's not saying that the criminal justice system shouldn't take account of people's personal and social circumstances. But he is worried that courts may think that mental illness makes people commit crimes. In fact, as I've pointed out before in a previous post, he doesn't think there's a place for psychiatric diagnosis.
It does worry me that the critical mental health movement gets caught up in an apparent split about the validity of the insanity defence. Thomas Szasz, of course, famously argued against the insanity defence, as he did not believe in the notion of mental illness. Essentially, he thought there is no need for any specific mental health legislation (see eg. previous post). Whilst I agree that mental health services should not insist that people accept that their problems are symptoms of an underlying illness, Peter seems to be verging, at least, on rejecting the notion of mental illness altogether. We might benefit from more clarity about whether he thinks there should be a Mental Health Act.
The point is that what is designated as mental illness may lead to mental incapacity. People who are psychotic may not make the most rational of decisions because of their mental illness. Crimes, including homicide, may be committed for psychotic reasons. It is generally accepted that it is wrong to punish a person deprived, even if only temporarily, of the capacity to form a necessary mental intent that the definition of crime requires. People should be presumed to have a sufficient degree of reason to be responsible for their crimes unless the contrary can be proved. But, in some cases people do appear to have acted irrationally because of mental disorder in committing their crime.
The legal test of criminal insanity in England was developed in the trial of Daniel McNaughton. On the 20th January 1843, Daniel McNaughton fired a pistol at point blank range into the back of Edward Drummond, the private secretary of the Prime Minister, Robert Peel. McNaughton may well have thought he was shooting the prime minister. In the magistrates court the next day he said, "The Tories in my native city have compelled me to do this. They follow, persecute me wherever I go, and have entirely destroyed my peace of mind." Although the court did not examine whether there was any element of truth to his claim and it was not explained why he had a bank receipt for a large sum of money on him when arrested, both the prosecution and defence agreed he suffered from delusions of persecution. No medical evidence was offered to say he was not deluded and the jury returned a verdict of not guilty by reason of insanity. McNaughton was admitted to Bethlem hospital and transferred to Broadmoor when it opened, where he died in 1865. His diminished responsibility for the homicide was accepted on the basis of his mental illness.
In practice, courts may well be sceptical of psychiatrists' assessment of mental illness. For example, see my post about the case of Anders Breivik. I do understand what Peter means when he asks whether we really need the notion of mental illness to determine a Court adjudication. He seems happier with the notion of psychosis, so maybe we should use that term. Whatever we call it, mental dysfunction can diminish responsibility for a crime. Personally, I am happy to see such psychotic dysfunction as illness, in the same way as bodily dysfunction is illness. The real problem is seeing mental illness as brain disease (e.g. see another previous post).