If they shouldn't be punished, what would you recommend? I don't have a well-informed suggestion.
When you have a person that commits crimes due to severe mental issues, you could observe that:
- punishment won't work as a deterrent
- punishment definitely won't work as resocialization tool
- it's of questionable morality to blame a person for things they have no control over
Applying punishment in such cases will cost money and make the criminal suffer, for no gain in the safety of the society. I.e. it's literally spending money just to mistreat someone.
So what are the alternatives? If the condition is treatable, let's treat it instead. If the condition is not currently treatable, you can isolate the person from society - but this will already win you all the safety you can get, so there's no point in punishing them further.
Of course the issue is complex, because most variables here have pretty blurry borders.
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Anyway; basically, I'm of the opinion that one should use methods effective for the purpose at hand. If your goal is to ensure safety of the society, punishing mentally ill people is not helping. On the other hand, if your goal is to give the society a sense of revenge, then by all means torture people - just be honest about what the real goal is.
It's gets interesting that when a person with a treatable condition doesn't want to be treated.
We have to remember here that some prisoners are a danger even to their cellmates--I've heard of some who threatened to kill any cell mate, then did so. For that population of violent people who are a danger to everyone, isolating them could be both harmful to the prisoner, but the right move for society.
Though I suppose it's an open question whether executing such prisoners would lead to less suffering.
After several years, it became apparent that this decision simply shunted the responsibility of managing dangerous and mentally unstable individuals--particularly those too poor to afford private treatment--to the prison system.
So now all the prisons and jails are also de facto mental health clinics--plus gratuitous punishment that is virtually guaranteed to have no impact whatsoever of the recidivism rate for the subjectively crazy inmates.
Some of my fellow Americans have some rather warped and irrational opinions on mental illnesses, taking them as weakness of character, rather than diseases to be cured, treated, or managed under the direction of a competent specialist. This allows them to rationalize the management of crazy people as someone else's problem, and the struggles faced by those with mental impairments or disorders as largely their own fault. Those people often hold other irrational beliefs. They may also think that one's sexuality is a choice that can be changed. Or they may believe that week-old fetuses have greater value than their mothers. Or they may believe that using a recreational drug is criminal behavior that warrants being locked in a cage for years. And they vote. Those elected to office with the support of their votes may also support their views with legislation as a means of retaining that support for reelection. And so it goes. Rational governance loses sway in the face of an ignorant populace.
I would recommend screening all current prison inmates for objectively measurable symptoms of cognitive impairments, brain damage, and personality disorders, at state expense. Then transfer those with confirmed diagnoses to dedicated treatment facilities, not punishment boxes. And aside from the diagnosed individuals, criminal behavior is itself a symptom of a disease in society. Punishing a poor person for being ignorant and making his own selfish opportunities will not solve the underlying problem, which is that society generally expects work in exchange for the means of survival, and withholds work opportunities from those it finds to be unpopular or otherwise undesirable.
This would be much less severe a problem if the US health care industry were less oriented to private profits and more oriented towards the general welfare. And it would be less severe if "tough on crime" candidates for political office aimed for more prevention and less punishment.
It's a vicious cycle since homelessness/the mentally disturbed are an issue everyone wants to go away, but not spend a lot of money on.
I think part of the issue here is that, in the past, mental health institutions itself had their own huge issues. There was a large movement to move away from mental health institutions, at least in the US, in the 1970s as a result (https://en.wikipedia.org/wiki/Deinstitutionalisation). The unfortunate consequence is that, instead of community-based mental health systems rising up to address the wrongs of the mental health institution, as envisioned by the de-institutionalization movement, the prison has ended up somewhat taken its place (https://thesocietypages.org/sociologylens/2012/07/03/deinsti...).
There was a new generation of drugs people thought would end the need for institutions. I don't think they even considered the possibility people with mental illnesses would, in a state of mental soundness, decide not to take the drugs necessary to keep them there.
There was also a bit too much optimism when it came to assessing the effectiveness of the drugs.
I'm not comfortable with these folks being in prison before they've had proper mental health care, honestly. Most folks with mental disorders are OK once they are stable with medication and sometimes need support to make sure they take such medication. We should more likely require by court order they stay their course and continue to receive proper help than try solitary first. This is how you treat the same folks as neighbors.
If this fails, prison is still not the proper environment - a live-in mental health hospital is much more appropriate.
Much more expensive and there are much less investors for such facilities. So it's not going to be a solution anytime soon.
It could easily be a solution if we switched away from a mass-incarceration, punishment above rehabilitation regime like in Norway as described towards the top of this thread.