Mapp v. Ohio Case Brief

Facts of the case

Dollree Mapp was convicted of possessing obscene materials after an admittedly illegal police search of her home for a fugitive. She appealed her conviction on the basis of freedom of expression.

Why is the case important?

Police officers sought a bombing suspect and evidence of the bombing at the petitioner, Miss Mapp’s (the “petitioner”) house. After failing to gain entry on an initial visit, the officers returned with what purported to be a search warrant, forcibly entered the residence, and conducted a search in which obscene materials were discovered. The petitioner was tried and convicted for these materials.


Whether evidence discovered during a search and seizure conducted in violation of the Fourth Amendment of the Constitution shall be admissible in a State court?


Justice Tom Clark (“J. Clark”) filed the majority opinion. No, the exclusionary rule applies to evidence obtained in violation of the Fourth Amendment’s search and seizure clause in all State prosecutions. Since the Fourth Amendment’s right of privacy has been declared enforceable against the States through the Due Process Clause of the Fourteenth Amendment, the same sanction of exclusion is also enforceable against them. The purpose of the exclusionary rule is to deter illegally obtaining evidence and to compel respect for the constitutional guarantee in the only effective manner. Otherwise, a State, by admitting illegally obtained evidence, disobeys the Constitution that it has sworn to uphold. A federal prosecutor may make no use of illegally obtained evidence, but a State prosecutor across the street may, although he supposedly is operating under the enforceable prohibitions of the same Amendment. If the criminal is to go free, then it must be the law that sets him free. Our government is the potent, omnipresent teacher. For good or for ill, it teaches the whole people by its example. If the government becomes a lawbreaker, it breeds contempt for law.


The Court held that the due process clause of the Fourteenth Amendment extended to the States the Fourth Amendment right against unreasonable searches and seizures. And, as necessary to ensure such rights, the exclusionary rule, which prohibited the introduction into evidence of material seized in violation of the Fourth Amendment , likewise applied to the State’s prosecution of state crimes. The Court reversed the judgment of the state supreme court and remanded the cause for further proceedings not inconsistent with the Court’s opinion.

  • Advocates: –
  • Appellant: Dollree Mapp
  • Appellee: Ohio
  • DECIDED BY:Warren Court
  • Location: Mapp’s Residence
Citation: 367 US 643 (1961)
Argued: Mar 29, 1961
Decided: Jun 19, 1961
Mapp v. Ohio Case Brief