Probable Cause

Probable cause is a requirement found in the Fourth Amendment that must usually be met before police make an arrest, conduct a search, or receive a warrant.  Courts usually find probable cause when there is a reasonable basis for believing that a crime may have been committed (for an arrest) or when evidence of the crime is present in the place to be searched (for a search).  Under exigent circumstances, probable cause can also justify a warrantless search or seizure.  Persons arrested without a warrant are required to be brought before a competent authority shortly after the arrest for a prompt judicial determination of probable cause.