"...the "dangerous to oneself or others" criterion for involuntary commitment has been around for at least 40 years.

Longer than that. Serious efforts were made in the 1950s to liberate mental patients and prevent them from getting awful things done to them such as electro-shock treatment and lobotomies.

People keep bringing up the name of Reagan when talking about dumping crazy folks out into the stereet, but California's state mental hospitals had 37,000 patients in 1959, at the peak. By the beginning of 1967, when Reagan took office as governor of California, the number was down to 22,000, only about 60% of the 1959 number. That was done under "Pat" Brown, Jerry "Governor Moonbeam" Brown's father.

The California Legislature, a few months after Reagan began his first term, introduced the Lanterman-Short-Petris act which is, essentially, a mental patients "bill of rights".

I believe that L-S-P allows for involuntary commitment for up to 72 hours for the purpose of evaluation. The order to evaluate can come from only three groups of people: law enforcement officer, school teacher or judge.

What Regan did was follow the mandates of L-S-P which resulted in most institutionalised patients going into "halfway houses" by 1970.

The Pima County shariff knew about the Tucson shooter for perhaps 3 years and could have demanded that he be committed temporarily for evaluation. Had he done so, the FBI check probably would not have come back as clear.