Drunk driving?

Generally, no, not for them getting a DUI. Now if they cause injury or death, the prosecution may contend that through a chain of causation, you were the last one who served him alcohol and therefore share in culpability, but that is erally hard to prove. I would recommend however, that for future parties at your house where you serve alcohol, take everyone's car keys that are drinking, and let them know that you will not give them back if they have had too much and either you or someone you trust to make those types of judgments stay sober so that the clear mind has a chance to prevail. Ya you may end up with a room full of drunks crashed on your sofa's, floor, sleeping bags or whatever, but everyone stays safe.

No but if you provide the liquor and they leave your house visably intoxicated and get into an accident you may be liable under a Dram Shop law.

No, but if you were aware that the person of age was too drunk to leave your house you might be in the wrong so be careful.

i think that they could sue you. if they cause damage to property or kill somone, i believe you can be charged as an accessory to the crime. the easiest solution is to have sleepovers if you;re going to be doing a lot of drinking.