An update--
My son went to his court-ordered substance abuse evaluation yesterday and they've set him up with weekly substance abuse counseling, which he thinks will be some kind of group meeting. He's also got individual counseling sessions that will be arranged and a monthly meeting with his probation officer. They did two drug tests yesterday and he said they'll test him at the weekly substance abuse meetings. I asked him what happens if he fails one of the tests, and he said they'd probably make him go to more counseling at first, but if he failed more than one or two times he'd probably have to go to jail. He seemed very pleased to be getting the services and said he's talked to his boss about everything. All the meetings are outside of his work time except for the monthly probation appointments.
Guarded optimism here, as I'm learning.
A side-note--Isn't it interesting (unfortunate) that it seems like a person of limited financial resources can get treatment through the court system but not otherwise? My son had tried several avenues to get treatment services before, but you either had to have private insurance, tons of money, or be put on a long waiting list.