First off I'm not a lawyer so maybe Jeff or another lawyer will help but Florida law allows you to seek a court order require that your son be evaluated to determine if he is fit to take care of himself. The law reads as follows:

[I]f there is reason to believe that he or she is mentally ill and because of his or her mental illness:

(a) 1. The person has refused voluntary examination after conscientious explanation and (a) disclosure of the purpose of the examination; or

(a) 2. The person is unable to determine for himself or herself whether the examination is (a) necessary; and

(b) 1. Without care or treatment, the person is likely to suffer from neglect or refuse to care for himself or herself; such neglect or refusal poses a real and present threat of substantial harm to his or her well-being; and it is not apparent that such harm may be avoided through the help of willing family members or friends or the provision of other services; or

(a) 2. There is a substantial likelihood that without care or treatment the person will cause serious bodily harm to himself or herself or others in the near future, as evidenced by recent behavior.

I would think that other States have a similar law on their books.