There are two kinds of vehicle stops, traffic stops, and checkpoints. At a checkpoint, you are not able to contest the validity of the stop except in rare circumstances. Checkpoints are not viewed as investigatory, they are classified as public safety and health initiatives, therefore, criminal protections do not extend to them (even though the practical effect is the same). But, you can contest a traffic stop. This post will go over the requirements for a valid traffic stop and how you can dispute them.
To stop a car, the police need to have a reasonable suspicion based on articulable facts that something illegal is occurring, recently happened, or will occur soon in the vehicle. That means that the officer is not allowed to stop cars at random, he must have a reason. Second, that reason must be based on articulable facts. That does not mean the facts are objective; they can be based on the officer's subjective understanding and determinations.
The most common justification for DUI stops is that the officer discerns that you were driving erratically, failing to signal, stopping at random intervals or unable to maintain a constant speed. Once the officer sees that, he can pull you over. At that point, he is allowed to question you, and if he smells alcohol or notices your speech is slurred, then he can submit you to a field sobriety test.
But, if none of those factors are present, you are permitted to challenge the traffic stop. If the stop is ruled inappropriate, then all evidence that is gained as a result of the stop is ruled inadmissible under the exclusionary rule.
If you were arrested driving while intoxicated, then you may want to speak to a defense attorney. A lawyer can go over the details of your traffic stop to ensure that the officer obeyed all constitutional requirements and did not violate your rights. The sad fact of these stops is that most of them turn on a few facts and interpretations, therefore, these arguments are hard to make for non-lawyers, and many people are taken advantage of by the police and prosecutors. A lawyer can ensure that your rights are respected.