Prohibits unreasonable searches and seizures and sets requirements for search warrants based on probable cause. Proposed September 25, 1789; ratified December 15, 1791, 2 years and 2 months later. The Fourth Amendment to the United States Constitution is part of the Bill of Rights. It prohibits unreasonable searches and seizures and sets requirements for issuing warrants: warrants must be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized. Wiki link