If a police officer searches your car without a warrant, will the evidence they find be valid in court?

The 14th amendment protects against unlawful search and seizure. If the police search your car without a warrant, your permission or a valid reason, they are violating the law. That having been said, under the "automobile exception" to the search warrant requirement, individuals have a lower expectation of privacy when driving a car. In other words, not every police search must be made pursuant to a lawfully executed warrant. Such a search can take place under the following circumstances:

1. You have given the officer consent;
2. The officer has probable cause to believe there is evidence of a crime in your vehicle;
3. The officer reasonably believes a search is necessary for their own protection( eg a hidden weapon); or
4. You have been arrested and the search is related to that arrest (such as a search for illegal drugs).

Automobiles may be stopped if an officer possesses a reasonable suspicion that the driver has violated a traffic law. If the reason for the stop is a minor traffic offense like speeding, the officer likely isn’t permitted to search your car without more reason. However, if police arrest for conduct arising out of a traffic stop, a search of your vehicle incident to arrest will usually be allowed. Additionally, if the police have impounded your vehicle, they have the legal authority to search it, which may or may not include opening any locked compartments or boxes found within your car. The reason for your car impounded does not matter; in fact it could be for nothing more than a parking violation.