You may naturally feel nervous if the police pull you over, especially if you had something alcoholic to drink earlier in the evening. It is paramount to remember your rights and that the police cannot search your vehicle without probable cause. For example, a cop may have pulled you over for having a broken taillight, but that is not an excuse to search the rest of your car to see if any drugs or alcohol are in the vicinity.
The police officers may ask you to take a breath test or perform field sobriety tests to determine if you are under the influence of alcohol. In the event the cop arrests you on suspicion of DUI, then he or she can search the vehicle and may need to do so to take inventory of all possessions for when the tow truck takes it to the impound lot.
To search a car or house, a police officer normally needs to acquire a search warrant if there is not apparent evidence a crime has taken place. However, it is possible the officer will ask you if it is all right to search your vehicle. You may think nothing illegal is around, but he or she may find something. If you gave permission, then that evidence becomes admissible in court. However, if the cop searches your car without your consent and before arrest, then anything the officer finds, whether it is half-empty beer bottles or marijuana, cannot come up in court.
Authorities can also search your car prior to arrest if there is probable cause a crime took place. For example, an empty beer can may be in plain view, and the officer sees it easily from the window. This could give the officer cause to believe you drank while driving. It is a good idea to familiarize yourself with your rights if you believe an officer unlawfully searched your vehicle.