The US Constitution protects all citizens from unreasonable searches and, in most cases, law enforcement personnel are required to obtain a warrant before conducting a search. There are, however, exceptions to this rule. If officers have a good reason – known as “probable cause” – to believe that a vehicle contains an illegal item, such as drugs or weapons, they can conduct a search without a warrant and without the driver’s consent. There is, however, one important caveat: the police can only search in the area where they believe the items are located. Similarly, officers can make a warrantless search of a vehicle after they arrest its driver. They cannot, however, search the trunk.