Question

When faced with a friend who is trying to drive under the influence:

Answer 1

When faced with a friend who is drunk either try to talk him into giving up his keys and having them take a taxi or have someone sober take him. If conversation is an issue you could try and take his keys from, although if he gets violent call the police.

Answer 2

Tell your friend not to drive, but if he doesn't do so, it would be a good idea to call 911 and save lives.