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 issue, 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.
At common law, a police officer could arrest an individual if that individual committed a misdemeanor in the officer's presence or if the officer had probable cause to believe that the individual was committing a felony. For misdemeanors, probable cause to believe that a wrongdoer committed a misdemeanor is not sufficient for an arrest; the police officer has to actually witness the misdemeanor.