The horse has already vacated the barn, but it's still not a bad idea to tell your son to lock down access to his Facebook to ACTUAL friends and family only. It's never too early to protect your personal information and your online interactions from prying eyes. Additionally, one should never post anything to Facebook/Twitter/G+/MySpace that they would find problematic if it appeared on the evening news.Basically it boils down to how the school started punishing these students for giving their opinion on Twitter and Facebook, about something they were witnessing at school that they felt inappropriate.
For help finding an attorney, contact your local Bar Association for a referral. If you're within rock-throwing distance of a law school, you might also look into whether they offer clinic days, during which you can talk to someone who can point you to additional resources.

