In most cases, you’ll be stopped for a traffic infraction. Then, if the police officer feels that you are intoxicated he may request that you take some field sobriety tests. These field sobriety tests are done by law enforcement at the scene of the traffic stop. The officer may decide to have you perform these tests if he smells alcohol on your breath, if he notices slurred speech, or for any valid reason determined by the police officer. They must detect at least two clues of intoxication.