All evidence obtained by searches and seizures in violation of U.S. Const. amend. IV is, by that same authority, inadmissible in a state court.
It was apparent that the materials introduced into evidence in the prosecution of Mapp were seized during an illegal search of her residence in violation of the Fourth Amendment. Nevertheless, the state supreme court affirmed Mapp's conviction for possessing lewd material in violation of Ohio Rev. Code Ann. § 2905.34 on the basis that the Fourteenth Amendment did not apply in the state court prosecution of Mapp for a state crime to forbid the admission of evidence obtained by an unreasonable search and seizure. On appeal, Mapp's contended that the evidence seized during a search and that was introduced at the trial was prohibited under U.S. Const. amend. IV.
Should the evidence be excluded from trial under the exclusionary rule?
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.