Judicial branch · Landmark case
Mapp v. Ohio
367 U.S. 643 (1961) · Opinion of the Court
What you should know
This page explains the Court’s holding in plain language.
The controlling document is the Court’s opinion.
The Court held that evidence obtained through a search and seizure that violates the Fourth Amendment is inadmissible in a state criminal trial. The exclusionary rule, previously applied in federal courts (Weeks v. United States), is an essential part of the Fourth and Fourteenth Amendments and binds the states. Wolf v. Colorado, which had refused to incorporate the exclusionary rule, was overruled on that point.
Background
Cleveland police forced their way into Dollree Mapp’s home without a proper warrant while looking for a bombing suspect and illegal betting equipment. They found obscene materials and prosecuted her under state law. The Ohio courts admitted the evidence. The Supreme Court used the case to incorporate the exclusionary rule against the states.
Mapp made the exclusionary rule a nationwide constraint on police searches.
Illegally obtained evidence cannot be used in the prosecution’s case-in-chief in state or federal court. Later decisions created exceptions (good faith, inevitable discovery, independent source), but the core rule remains a central feature of Fourth Amendment practice.
Vote and authorship
| Majority | Clark, J. |
|---|---|
| Join | Warren, C.J., Black, Douglas, Brennan |
| Concurrence | Black, J.; Douglas, J.; Stewart, J. (in judgment) |
| Dissent | Harlan, J. (joined by Frankfurter, Whittaker); Whittaker, J. |
Our decision, founded on reason and truth, gives to the individual no more than that which the Constitution guarantees him, to the police officer no less than that to which honest law enforcement is entitled, and, to the courts, that judicial integrity so necessary in the true administration of justice.
Justice Clark · Mapp v. Ohio
How it fits in government
Fourth Amendment
Exclusionary rule as a remedy for unconstitutional searches.
Judicial branch
Incorporation of a key criminal-procedure protection against the states.
State & local government
Requires state courts to exclude illegally obtained evidence.
Official records visitors may need
Related research paths
Fourth Amendment
Search and seizure
Gideon v. Wainwright
Related incorporation of fair-trial rights
Criminal procedure
Warren Court reforms