Just because you are pulled over does not automatically give police the right to search your vehicle. Law enforcement may only search a vehicle, home, person or thing if they have: (1) a search warrant, (2) consent, or (3) probable cause (a reasonable ground for belief of guilt). The mere fact that you are pulled over for a traffic violation is not probable cause to search your car. An officer would need additional "justification" or probable cause to search. Because of this, officers often ask for your permission or consent to search. However, you never have to let the police search your car or home just because they ask. All persons have an absolute constitutional right to say NO if they are asked to consent to a search, and saying no is not, in and of itself, grounds for a search. Law enforcement usually requests consent to search because it eliminates the need for a warrant or probable cause. Obtaining a warrant is a time-consuming process and probable cause often does not exist.