This already happens in small numbers with criminal law, and society has accepted it as a cost of doing business.

It's a travesty, but unavoidable. The situation we're in right now in the US is that a handful of mentally ill chronic homeless people can render public areas unusable for millions. My city effectively has no parks or libraries any longer, the entire downtown area smells like human waste, and it's now unsafe to be out at night due to roving packs of the mentally ill.

Ask why laws and punishments exist in liberal democracies, and then ask yourself why that exact same reasoning doesn't apply to the severely mentally ill.

The same argument could be made for the criminal code in those states. Authoritarians will always find a way to abuse authority. Yet, we need rules and enforcement for society to function.

As I mentioned in another subthread... I live in a metro area of 4M people and we don't have a single usable public park or library. The chronic homeless are more ruinous to society than most criminals.

The chronic homeless are impoverished and lack housing because they are mentally ill. They need actual medical help, because they lack the ability to fix their situation on their own.

When the DotCom bubble burst, I was working at a job center for my local government. My role was to find jobs for the homeless, convicted, and people on the sex offender registry. People that were homeless because they fell on hard times were in and out quickly -I never saw them again once I lined up an interview. But the mentally ill ones -it didn't matter how much you cleaned them up and prepared them, it didn't matter how many interviews you sent them to or even how many jobs they got. They just couldn't hold down employment.

When I talk about severely mentally ill homeless people, you're probably imagining the guy shuffling down the street mumbling to himself, or the one shouting at cars. Yes, those guys need help, too. But I'm also talking about the guy who seems completely sane, until he decides to trust you with the secret that his wife and Tom Cruise are plotting together to have him assassinated. Those guys are all over and pretty good at hiding how severely mentally ill they are. But their illness prevents them from holding down a job (eventually the boss is In On It or whatever) and often the paranoia prevents them from wanting to stay in one spot for long.

They need actual forced medical care, not a place to sleep and the option to volunteer for treatment (it's a ploy by Tom Cruise, you see).

I wish I was making the Tom Cruise example up for the sake of rhetoric. That guy went on to sneak through the job center and steal a bunch of files on people, before disappearing.

Sometimes it's even more subtle.

I'm not sure what this means.

Telling people how to behave and locking them up if they don't follow your rules is pretty illiberal. Yet every liberal democracy still has laws, and prisons. Why?

That's why you write evaluation and sentencing guidelines. Mental health issues that don't ruin public spaces and put people in imminent physical danger around you would never even see the inside of a courtroom, let alone be committed.