In practice, one is usually only taken away in a rubber truck to a psychiatric institution for evaluation only if the individual has shown or made statements indicating he/she poses an imminent actual danger to the lives of him/herself and/or others.
Given the lack of mental health funding/hospital beds in such institutions in many areas of the US, past histories of involuntary commitment being abused by authorities for dubious motives in the past, and the possibility of a strong case for a lawsuit against civil authorities/municipalities for wrongful involuntary commitment as Kam Brock’s case against the NYPD/NYC proves: