Who said everyone had to quit their jobs to join this program? I thought it was about regular citizens being better trained to be aware of crime. They're not actually Cops. They don't get paid. They're still citizens.

Yeah.. I figured he was kind of a lousy lawyer..

I think he was a bit of an ambulance chaser anyway - a bit of a Lionel Hutz.

Is it ever explained why a lawyer would quit to join a volunteer police program?
Might look good on a resume, or if he had political ambitions. He's a public defender, so if he ran for office of some sort he might want to go ahead and do some damage control, for when an opponent accuses him of being soft on crime.
But yea, he was rather pointless. It's possible he might have had a bigger role, but ended up having most of his scenes cut.