I'm sorry I can't offer any advice. I can say that I'm in the exact same position except my son is 21 and graduating college this year and was arrested a few months ago for public intoxication (I think was the charge).
We gave him the option of staying home and following the rules or moving out on his own. He moved out on Sunday.
This thread pretty much sums up where we are now.
http://www.soberrecovery.com/forums/...d-hopeful.html
We should stay in touch since it seems we are at the same place in the process with sons that seem to be in the same place in their lives.