The Fourth Amendment of the Constitution protects United States citizens against unreasonable searches and seizures by the government and requires all warrants to be supported by probable cause in order for them to be issued. The protections of the Fourth Amendment are implicated where an individual has a reasonable expectation of privacy. Although a warrant is required prior to conducting a search, there are some exceptions that allow law enforcement to conduct warrantless activity.
Generally, police are allowed to perform searches without a warrant when they were acting in exigent circumstances. Exigent circumstances may exist where there is a risk of a suspect getting away, when police have reason to believe evidence will be destroyed, or where there is a risk of harm to the police or to the public. If the police are acting under exigent circumstances, or if an individual does not have a reasonable expectation of privacy, a warrantless search will be allowed. The following are some of the more common scenarios where law enforcement may conduct a search without a warrant: