Mapp v. Ohio in 1961 impacted the type of evidence admissible in court, according to About.com. The U.S. Supreme Court ruled that evidence acquired through illegal search and seizure was not admissible evidence. Justices used the Fourth Amendment to find in favor of Mapp. In 1984, United States v. Leon restricted this ruling to exclude seizures made while the officer acted in good faith.
In 1957, Cleveland, Ohio, police entered the home of Dollree Mapp without a warrant or permission to search. They were looking for a bombing suspect, according to the Administrative Office of the United States Courts. Though the police did not find the suspect, they did find obscene pictures in Mapp’s possession that violated state law. They arrested her and subsequently convicted her for the pictures obtained during their search. Mapp appealed her case up to the U.S. Supreme Court, which found five to three in favor of Mapp. The specific questions in front of the U.S. Supreme Court also included a question on obscenity and the First Amendment, according to The Oyez Project. The Justices did not rule on the First Amendment question.
The Fourth Amendment to the U.S. Constitution protects against unlawful search and seizure, according to Cornell University Law School. It demands a warrant with probable cause to conduct a search.