The Florida Mental Health Act of 1971 (commonly known as the "Baker Act") is a Florida statute allowing for involuntary examination of an individual.
The Baker Act allows for involuntary examination (what some call emergency or involuntary commitment). It can be initiated by judges, law enforcement officials, physicians or mental health professionals. There must be evidence that the person
has a mental illness (as defined in the Baker Act) and
is a harm to self, harm to others, or self neglectful (as defined in the Baker Act).
Examinations may last up to 72 hours and occur in over 100 Florida Department of Children and Families-designated receiving facilities statewide.
There are many possible outcomes following examination of the patient. This includes the release of the individual to the community (or other community placement), a petition for involuntary inpatient placement (what some call civil commitment), involuntary outpatient placement (what some call outpatient commitment or assisted treatment orders), or voluntary treatment (if the person is competent to consent to voluntary treatment and consents to voluntary treatment). The involuntary outpatient placement language in the Baker Act took effect in 2005.http://en.wikipedia.org/wiki/Baker_Act
So it's a Florida law but maybe it's been copied by other states?
I'm in the western US too. In my state, if someone is found to be a danger to herself or to others, she can be institutionalized for up to a year. A friend of mine - his wife developed schizophrenia and refused medication; she was court-ordered to take the meds and a local facility was ordered to administer them; but she refused and that institution didn't do their job. So then she was institutionalized, in a Midwestern state since she had gone there without the court's knowledge.
Long story short, I'm sure the law varies a lot from state to state. Most states have their laws online now - tough to search but maybe you can find something, or do a short (maybe free) consultation with a local lawyer to find out more.