Chris talks about what to do if you've caused an accident while drinking and driving. DON'T drink and drive!
OK you've been drinking, and you just hit someone from behind. How much trouble are you in? Maybe a lot.
You need to, first of all, find out if the person that you've hit is OK. Second, you should probably call a criminal defense lawyer - not an injury lawyer. Find out what you should do next.
If you're arrested be sure and talk to a lawyer before anything gets said to a police officer.
I don't handle criminal cases, but if you've been drinking, you need to talk to a criminal lawyer.