Mapp v. Ohio is considered a landmark case involving Fourth Amendment protections against unreasonable or warrantless searches and seizures. The Supreme Court decided in favor of the petitioner, Dollree Map, and against the State of Ohio in its 1961 ruling.
The case began with the 1957 arrest, prosecution and conviction of a Cleveland, Ohio, female for possession of pornographic material inside her home. As the case developed, it turned out that the police officers involved had entered her home on the pretext of searching for bomb-making equipment. Mapp had initially declined the police officers' request to search her home, but, after some of the officers left and later returned with a piece of paper they claimed was a valid search warrant, yet which they refused to show her, Mapp grabbed the paper and stuffed it down her shirt. The officers forcibly restrained her and took the paper back. The officers proceeded to conduct the search, wherein the pornographic material was discovered and seized, and Mapp arrested.
Mapp v. Ohio, as indicated, would make its way to the United States Supreme Court, which decided in Mapp's favor and overturned her conviction. The Court determined that Mapp had been a victim of an unreasonable search and seizure in violation of her constitutional rights under the Fourth Amendment, which reads:
"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 probably cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."[Emphasis added]
In addition to the ruling that Mapp's Fourteenth Amendment rights had been violated, the Court's decision reaffirmed the preeminence of federal law over state law, meaning that the no law passed by a city or state can take precedence over one passed at the federal level of government.