Mapp v Ohio

Michelle Mun 4A

Basic Facts

  • Dollree Mapp lived in Cleveland, Ohio and was suspected of hiding a suspected bomber.

  • She refused to allow the police to come into her house without a search warrant.

  • The police illegally searched Mapp’s house without her permission and found obscene materials that were illegal in the state of Ohio.

  • Mapp was tried and convicted for these materials and appealed her conviction on the basis of freedom of expression.

Issue Before the Court

Were the confiscated materials protected by the First Amendment? (May evidence obtained through a search in violation of the Fourth Amendment be admitted in a state criminal proceeding?)

  • Mapp appealed her conviction based off of the 1st Amendment (freedom of expression).

  • However, the court brushed aside that issue and focused more on the illegal search and seizure that violated the 4th Amendment.

  • Police had a probable cause (the suspected bomber in the house), but they didn't follow through with procedural due process (didn't obtain a search warrant).

  • By ruling that the exclusionary rule does apply when the 4th Amendment is violated in state cases, the Court applied the federal exclusionary rule to the states through the doctrine of incorporation.


  • The Court decided that illegally obtained evidence be dismissed from court at all levels of the government since the evidence was obtained by searches and seizures in violation of the 4th Amendment, a.k.a the exclusionary rule.

Now the exclusionary rule affects both state and federal levels instead of just the federal level


  • Historic- Although the exclusionary rule was established before this case, it wasn't until Mapp v. Ohio that the exclusionary rule was applied to all states rather than just on the federal level.

  • Present- The exclusionary rule guards against unreasonable search and seizures and encourages police to perform search and seizures legally since any evidence they find during an illegal search will be thrown out in court. It can also cause difficulties for the Court to decide how they will apply the rule.

Ex) If the police were trying to convict a suspected drug dealer, they would want to go get a search warrant in order to search the house for drugs instead of forcing themselves in without a warrant because then any drugs or money they would've obtained as evidence would not be able to be used in court.

  • Future- The exclusionary rule can cause some controversy since the requirement for ensuring that evidence was legally-obtained was placed on the Court. The Court now faces the decision of how to apply the exclusionary rule in different cases.

Ex) A police officer believed he had a valid search warrant but there was an issue with the warrant he wasn't aware of. The evidence he picked up was technically obtained illegally even though the officer believes his search was legal. The court could make an exception to the exclusionary rule if they decide the officer acted on good faith.

Mapp v. Ohio (1961)