Exigent circumstances. Probable cause along with exigent circumstances may justify a search or entry without a warrant.The Fourth Amendment protects you from unreasonable searches and seizures, so police can't search your cell phone without a warrant or your consent. Can police search my house without a warrant? Under certain circumstances, law enforcement can conduct a search of your home or person without a warrant. If police have a reasonable belief that evidence of criminal activity is present in a vehicle, they can search it without a warrant. In fact, it's considered perfectly legal to search your car without a warrant in many instances. A police officer must fill out an affidavit and present it to a neutral judge or magistrate to obtain a warrant. It also means that cops can't enter your house without a warrant based on probable cause under most circumstances. The Constitution and 4th Amendment protects many types of unreasonable searches and seizures, however, it does not protect against things left out on the open.