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 it is .08, and there is a national movement afoot to make that the limit in all states. In Washington, the limit is .08  In Washington, 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 breath.  Some states allow the taking of a person’s blood or urine. The use of a breath test is by far the most popular  method for trying to establish that drunk driving has occurred. In many cases, we have been able to successfully challenge the results of such tests in court, thereby preventing a conviction. An attorney experienced in drunk driving defense law is in the best position to advise a client on whether the "Breathalyzer" test results may be subject to challenge in his or her particular case.