Most people know that there is no excuse for getting behind the wheel of a vehicle while intoxicated, but that doesn't mean that they won't do it.
When people drink, their ability to make good decisions is often vastly reduced. They may know that what they're doing is dangerous but continue on to do it anyway -- or they may convince themselves that they're actually sober "enough" to drive.
In many cases, people may sincerely not know that they are so intoxicated that they should not be driving. Everyone is affected differently by alcohol, so learning your limit is very important. You can't judge your tolerance for alcohol based on anyone else's.
For example, if your friend has been drinking for a long time and knows that they can drink a couple of shots and still drive safely without being over the legal limit, the same may not be true for you. It's important never to take guesses about your blood alcohol content.
If you are going out and plan to drink, one of the easiest things you can do to eliminate the guesswork is to carry a personal breathalyzer with you. A personal breathalyzer, which is available for about $100, can quickly let you know how much alcohol is in your system. That can sometimes be an eye-opener for people who think that they are still sober after a few drinks! If you have one in your pocket, it may help you avoid a bad decision.
Keep in mind that any amount of alcohol in your system can affect your driving abilities, so there is no specific amount that is safe, only an amount that puts you over the legal limit. If you are pulled over and charged with drunk driving, make certain that you speak to an experienced defense attorney about your situation.