Most people do not realize that once you are pulled over for a traffic stop, that is already a "seizure" of your person and the Fourth Amendment immediately comes into play. One important factor to keep in mind is that "traffic stop" after 11 pm is, for all intents and purposes, a "DUI investigation stop." For example, it is much less likely that at three in the afternoon a cop will pull your new BMW over for a failed lane change signal, at three in the morning, you bet the cop will pull you over! So, what you need to realize is that once you are pulled over you have the right to refuse all searches and seizures. Depending on where you live, you do not have the right to refuse a breathalyzer, which is seen by many as a point of contention in and of itself. You can, however, refuse all other searches including field sobriety tests. Once you are pulled over the officer will then begin to collect "evidence" against you. This will range from everything from any odors from your breath to those field sobriety tests. One key element in all of this is that if the initial stop was unreasonable, since it is a "seizure" of your person, then the rest of the "evidence" the officer has gathered will be thrown out, or as we say in law practice, suppressed. It is vital that you have an experienced lawyer who can ascertain whether or not you were legally detained, and to seek appropriate remedies if you were not. Remember, never operate a vehicle if you are under the influence of any substance.