I'm not sure he has any legal recourse outside employment law, but the cops need to think twice about trying to get around Constitutional protections by using the mental health laws. If the guy is a real danger the hold does NOTHING to keep him from coming right back out and shooting down some people. NOTHING. If the guy isn't a danger then you've just put a sane man through hell and possibly created a killer where there wasn't one before. All around, a disgusting performance by the boys in blue.