The best prevention is preventing criminal behaviour. By taking care of mental health, community, opportunity and support.

Edit/Comment: best in this case does not mean cost-effective or easy ;)

The vast majority of violent criminals are not mentally ill.

I meant mental health, I didn't mean mentally ill. Mental health even includes being unhappy.

Not sure if violent acts are entirely random, I have not enough expertise on that. Currently I assume most acts of violence are not entirely random; and if they are, they are a mental/medical/neurological illness. And it might be perfectly normal to be dispositioned to be like this, but it would still be a problem.

It does not seem like a stretch to expand the definition of mental illness to include mental conditions which predispose to the commission of violent crimes. Certainly such conditions are maladaptive for the sufferer.

Most violence is morally motivated[1], so working on changing societal norms are most important. 1: http://www.doktorikool.ut.ee/kstt/orb.aw/class=file/action=p...

I don't see how reclassifying crime as illness is going to help anything except making psychiatry much less credible.

"neither can any other remotely reasonable public safety measure"

How about allowing citizens to carry their own protection?