If you go through a police checkpoint or are stopped for a suspected traffic violation, the officer may ask you to search your vehicle. Under the Fourth Amendment of the United States Constitution, you are protected from "unreasonable searches and seizures" and this right applies to your vehicle. However, police can search your car under certain circumstances. As with any legal situation, several factors can influence whether or not a search is considered unreasonable. If you suspect your rights have been violated, you should contact a criminal defense attorney.
The most straightforward situation when law enforcement can search a vehicle is if they have a warrant to do so. In order to obtain a warrant, a police officer must convince a judge that there is probable cause for a search. This means they must present evidence that a reasonable person would believe a crime occurred, was occurring, or was going to occur. The warrant will specify the scope of the search.
Law enforcement does not need a warrant if they comply with the Fourth Amendment and the search is considered reasonable.
Some of the situations when an officer can search a vehicle without a warrant include:
If an officer has probable cause, they can conduct a search. This is the case if there is evidence of a crime in "plain view" of the officer. You should be aware that "plain view" does not just include sight and can include other senses, such as smell or hearing. The law enforcement officer will need to demonstrate to a court that their search was legitimate in order for any evidence they find to be used in a case against the defendant.
A police officer can search a car if this is reasonably necessary for their protection, such as if they believe there is a hidden weapon. They must have evidence to support this belief.
The "automobile exception" (Arizona v. Gant) allows police to search a vehicle during the lawful arrest of a driver. This means they must already have probable cause to arrest you before they search. In addition, they also must reasonably believe that you still have access to the vehicle or that there is evidence related to the crime they are arresting you for within said vehicle. If they find evidence of other crimes during the search, this could still be legally admissible.
If your vehicle has been impounded by the police for any reason, they can search it. However, they cannot impound your vehicle solely for the purpose of searching it and must follow strict procedures to conduct this type of investigation.
Even if none of the above circumstances apply, the police can search your car if you give them consent. Drivers may agree because they are unaware that they have the right to refuse a search. If you are stopped and an officer asks to search your vehicle, you may respectfully decline.
If a police officer is conducting a search you believe is unlawful, express that you do not consent and request a lawyer. If the search continues, you can and should invoke your right to remain silent until you are able to speak with your attorney. Do not, under any circumstances, argue with the officer or try to stop them from conducting the search.