Usually, a person is not pulled over for drunk driving.  You are pulled over for something else, a minor traffic violation, the police smell alcohol on you, and it goes sideways from there.  At that point, your attorney must examine the underlying traffic offense to see if that offense really is an offense. 

It may surprise you but the police are hardly experts here.  For instance, I have seen people pulled over in Ohio for having only one working taillight.  But the law only requires one.  In fact, if you take a right or left turn, and the sign forbidding that practice is not in accordance with the state rules on size, height and so on, then the turn you took is legal.  So the lesson here is to examine the underlying reason that the police stopped you for in the first place.