What are my legal rights and obligations to my guests and the public when hosting a party serving alcohol?

I'm throwing my brother a send-off party before he deploys to Iraq. My husband is somewhat of an alcohol connoisseur that has basically aculated a full bar that will be at my guests' disposal. That said, I have already told my brother that no underage friends can attend this party because I don't want them sneaking drinks. However, for all his rowdy friends in their 20's who still aren't all that mature, what am I legally allowed to do if I spot one too drunk to drive. Is forcefully keeping someone from driving considered false imprisonment? What if someone gets drunk and destructive? I wouldn't want them to stay and continue their behavior, but I can't very well ask them to leave and put a drunk on the road. I want everyone to have a good time, but I don't want any medical, legal or peace-disturbing issues. Basically, I need to know what the rights are of a person who is impaired or intoxicated and what my rights and responsibilities are regarding guests on my property drinking my alcohol.