We might need to change the definition of a designated driver from noble abstainer to something along the lines of not as drunk as you.
The idea of having one person in a group agree not to drink so that everyone else can get home safely after a night of alcohol-fueled fun has been promoted as a way to reduce the dangers of drunken driving, especially among teenagers and young adults.
You can legally drink and drive in the United States, but there's a limit. In every state, drivers can't get behind the wheel if their blood alcohol content is .08 or higher, but the National Transportation Safety Board wants the states to lower the legal limit to .05 or even lower. Now, that would bring the United States into agreement with much of the rest of the world.