In retrospect, it's easy to say that obviously [insert mass shooter here] was crazy and should be locked up. In practice, consistently identifying people like to go engage in mass violence is difficult, if not impossible.
The old joke about serial killers, that the neighbors always say, "I can't believe that he did this. He was so nice," is has some grounding in reality. For every Jared Laughner, who was obviously developing a serious mental illness, there are many more people who appear to be totally functional until one day they snap.
You're
completely missing the point. The point isn't just to target future mass shooters, it's to seriously reevaluate the criteria under which
all seriously mentally disturbed individuals get involuntarily committed. Right now, as the law stands,
nobody can force you to get treatment for mental illness, unless a mental health professional (usually a local Community Mental Health worker) evaluates you and decides you are an
immediate danger to yourself and others. Then you get committed for three days in a psych ward, during which time the docs there evaluate you and make you take your meds. After three days, if you seem better (which you probably will be, since now your anti-psychotic drugs are having an effect), and no longer seem to want to do yourself or others harm, they let you out again.
At this point, the mental patient usually goes off his meds again shortly after release, and the cycle begins again. As I said, as an LEO, I see these people almost every day. I've even had to fight some of the ones who are violent. Some of them multiple times. And as I said, even in the cases where the person is genuinely not much threat to anybody, the result is loads of mentally ill people living in squalor in halfway houses, or wandering the street, suffering all the attendant physical health problems you'd associate with that lifestyle. As a system for caring for mentally ill people, it's simply not working, and in most cases, it's as cruel to the mentally ill subjects themselves as the old system ever was.
We need to broaden the criteria under which people can be committed against their will. Perhaps not to make it as easy at it was before the 1980s, but certainly to make it easier than it is now. Someone like Seung-Hui Cho or Adam Lanza almost certainly would have been committed to an asylum in the old days. Will this stop every mass shooting? No, it won't. But it could stop many, and incidentally, be better for the great mass of non-violent mental patients who have been let down by the current system of providing essentially
no care for them. Finally, by putting the focus on the mentally ill people, where it belongs, it allows us to defend the right to keep and bear arms and claim (in the eyes of the public), both the moral high ground, and a stance that doesn't make non-shooters look at us as nothing but obstructionists determined to stop people from putting an end to the violence (and yes, I know the gun control laws won't put a stop to the violence, but please bear in mind the low information voters don't necessarily see it that way).