Under the Fourth Amendment of the U.S. Constitution, as well as California law, citizens have the right to be free from unreasonable searches and seizures by the police. Although there are some exceptions, this means that police usually cannot search an individual’s house, car, or person without probable cause or a valid search warrant. If police search any of these places illegally, the evidence that they took during the search, such as evidence of drugs, will most likely be excluded from trial.