How do you stop your brother from driving drunk?

Tell him straight up that this the stupidest thing you can do. If he drinks that heavily everyday, talk to him about getting help or cutting back. Be his designated driver or make sure someone else has promised to be. Put in numbers for taxis and such in his phone and tell him he can call you or one of them anytime, you'll pay for the gas. But most of all just tell him you care about him and you don't want him killing himself or another and spending his life in jail for something so ignorant. This is not worth taking another's life, or an entire family.