In all drunk driving cases, the prosecution must prove that the defendant’s blood alcohol concentration at the time of the offense was at or above a statutory limit. In many states, the limit is .10 percent, but in others such as Texas it is .08, and there is a national movement afoot to make that the limit in all states. In order to prove the requisite level of alcohol in the blood of someone arrested for drunk driving, it is necessary to obtain a suitable sample of the arrestee’s blood, urine, or hair at the time of arrest. The use of a breath test is by far the most popular scientific method for establishing that drunk driving has occurred. Some defendants, however, have been able to successfully challenge the results of such tests in court, thereby preventing a conviction. Contact our local Houston criminal defense lawyers at The Law Office of David A. Breston.