The Fourth Amendment to the U.S. Constitution protects against unreasonable searches and seizures and requires law enforcement to have probable cause in order to conduct a search or make an arrest. The Fourth Amendment states: “The right of the people to be secure in their persons, houses, papers, and effects against unreasonable searches and seizures shall not be violated, and no warrants shall be issued but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched and the persons or things to be seized.”
In other words, the Fourth Amendment requires law enforcement to have a legitimate reason for conducting a search or making an arrest and to be able to demonstrate that reason (probable cause) to a judge or magistrate in order to obtain a warrant. Probable cause is an important protection against abuses of power by the police and helps to ensure that searches and arrests are conducted in a reasonable and legal manner.