There are many products on the market now that offer an individual the opportunity to check his/her BAC (blood alcohol content) before they drive. The most common of these is a personal breathalyzer. However, using a personal breathalyzer can be risky. Even the best breathalyzers, such as those used by police departments, must be calibrated frequently to ensure accuracy. Also, your BAC can continue to rise after you take a breathalyzer, especially if you have only recently stopped drinking for the evening. Remember, an officer can also arrest you if you appear to be "under the influence," BAC notwithstanding. The best advice we can give is that you do not drive after drinking. Period. Under any circumstances. Do not trust a personal breathalyzer, trust yourself and do not drive after drinking.