Generally, the Fourth Amendment's protection against unlawful search and seizure makes arbitrary police car searches illegal. If the police search your car without your permission or a valid reason, they are violating your constitutional rights. Typically, an officer must have reason to believe a crime has been committed (such as a DUI) before searching your car.

Under the Fourth Amendment, courts generally give police more leeway to search a vehicle, rather than a home. Known as the "automobile exception" to the search warrant requirement, individuals have less of an expectation of privacy when driving a car. Furthermore, this exception is based on public safety concerns such as drunk driving or excessive speeding.

So, when can the police search your car? Under the following circumstances:

• You have given the officer consent.
• The officer has probable cause to believe there is evidence of a crime in your vehicle.
• The officer reasonably believes a search is necessary to their own protection (a hidden weapon, for example).
• The officer has a valid search warrant.
• You have been arrested and the search is related to that arrest (such as a search for illegal drugs).

Consenting to a Search

Officers may ask you for permission to search your vehicle, but you may decline the request or simply remain silent if no warrant is presented. Even if you are unaware of your rights and consent to a search because you believe you have no choice, ignorance of the law is no defense and permission to search effectively waives your Fourth Amendment rights.

If an officer searches your vehicle without your permission, do not argue with the officer but remain silent. Under the "exclusionary rule," illegally obtained evidence cannot be used in a case against you.

Probable Cause

Probable cause exists when an officer has reason to believe a crime is being (or has been) committed, giving the officer the legal authority to conduct a search. For example, the police can search your car if your eyes are bloodshot and marijuana use is suspected, or if your car matches the description of a getaway vehicle used in a bank robbery.

Additionally, any evidence of a crime that is left in "plain view" of an officer may be seized and lead to a more thorough search. For example, an officer may conduct a search after seeing a glass pipe with drug residue on the car's dashboard. In that scenario, the evidence left in plain view establishes probable cause that a crime was committed.

Federal courts have expanded the plain view doctrine to include other types of sensory evidence, such as the smell of drugs emanating from a car's trunk (including that which is only detectable by a drug-sniffing dog) or the sound of a kidnapping victim in the back of a van crying out for help.

The threshold for "reasonable suspicion," on the other hand, is not as stringent as that which is required to establish probable cause. It is more than simply a "hunch" but does not necessarily involve indisputable evidence of a crime. For example, a motorist who is swerving from lane to lane may be drunk or just a bad driver, but this gives an officer reasonable suspicion to investigate further. See "What is Reasonable Suspicion for a DUI Stop?" to learn more.

Seeking Legal Advice

If you are still wondering, "When can the police search search your car?" or need help with an unlawful search and seizure defense, contact a DUI or traffic ticket lawyer in your area today. Police searches are a serious matter. Your attorney will be able to review the evidence in your case and help you decide whether to file a motion to suppress illegally obtained evidence.

For more information about laws governing an officer's search of your car, see "Vehicle Search and Seizure" in FindLaw's Traffic Laws section.