Unfortunately, you probably can't know if and when you're over the legal limit. It is not illegal to drive after drinking alcohol. In Georgia, it's illegal to drive when your blood alcohol content (BAC) is over 0.08 grams, OR if you're incapable of driving safely due to alcohol consumed before driving (whew!). The MADD folks want you to make a bright-line choice: if you're going to be driving, don't drink anything at all that has alcohol in it, OR if you know you're going to be drinking, do not drive for 24 hours. If you're a social drinker, that choice may be unrealistic.

There are "products" out there that you can buy to help you gauge your BAC, but they may give you a false sense of security. You can go here to calculate what someone of your body weight can safely drink and be under the legal limit. But BAC calculations may not take into account other factors: your metabolism rate, whether you've eaten recently and what you've eaten, what medications you take on a regular basis and what you took that day, and stress situations. Of course, it is equally illegal to drive (1) if you're taking prescription medication that affects your driving ability, (2) if you're under the influence of toxic vapors (glue sniffers, no driving!), (3) if the combination of alcohol and drugs impairs you or (4) if you've taken any illegal drug, other than marijuana, whether or not you're "high."

DUI is a subjective "crime." No one thinks that drugged or drunk driving is a joke; driving under the influence is much different than drunk driving, and that's why you probably can't ever tell if you're over the legal limit before you start driving home. The best way to avoid a DUI is to not drive unless you know how the alcohol is affecting you, you're very certain of how much you've had to drink over a certain length of time. If you've lost track of either, let someone have your keys.