The Fourth Amendment, however, is not a guarantee against all searches and seizures, but only those that are deemed unreasonable under the law. The Fourth Amendment to the U.S. Constitution protects individuals from unreasonable searches and seizures.Amendment Four to the Constitution was ratified on December 15, 1791. It protects the American people from unreasonable searches and seizures. The Fourth Amendment is the part of the Bill of Rights that prohibits "unreasonable searches and seizures. " But — what's unreasonable? Fourth Amendment Explained. The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated. The right to be free from unreasonable searches and seizures has its roots in English history. "Under the Fourth and Fourteenth Amendments, an arresting officer may, without a warrant search a person validly arrested.