The exclusionary rule is based on federal constitutional law. It excludes evidence obtained in violation of a criminal defendant’s Fourth Amendment right against unreasonable searches and seizures by law enforcement officers. If the search of a criminal suspect is unreasonable, the evidence obtained in the search will be excluded from trial.
Before the exclusionary rule was fashioned, evidence was admissible in a criminal trial if the judge found the evidence was relevant. The manner in which the evidence had been seized was not an issue. This began to change in 1914 when the United States Supreme Court devised a way to enforce the Fourth Amendment in recognition of police misconduct. In Weeks v. United States, 232 U.S. 383, 34 S. Ct. 341, 58 L. Ed. 652 (1914), a federal agent had conducted a warrantless search for evidence of gambling at the home of Fremont Weeks. The evidence seized in the search was used at trial and Mr. Weeks was convicted. On appeal, the United States Supreme Court held that the Fourth Amendment barred the use of evidence secured through a warrantless search. Mr. Weeks’s conviction was reversed and thus was born the exclusionary rule.
The exclusionary rule established in Weeks was constitutionally required only in federal court until Mapp vs. Ohio, 367 U.S. 643, 81 S. Ct. 1684, 6 L. Ed. 2d 1081 (1961). In Mapp, Cleveland police officers had gone to the home of Dollree Mapp to ask her questions regarding a recent bombing. The officers demanded entrance into her home. Ms. Mapp called her attorney and then refused to allow the officers in without a warrant. The officers became rough with her, handcuffed her and searched her home. They found allegedly obscene books, pictures and photographs. Ms. Mapp was charged with violations of obscenity laws, prosecuted and convicted. Her conviction was affirmed by the Ohio Supreme Court but overturned by the United States Supreme Court.
In Mapp, the Court held that the exclusionary rule applied to state criminal proceedings through the Due Process Clause of the Fourteenth Amendment. Before Mapp, not all states excluded evidence obtained in violation of the Fourth Amendment. Since Mapp, a defendant’s claim of unreasonable search and seizure has become a matter of course in most criminal prosecutions.
A criminal defendant’s claim of unreasonable search and seizure is usually heard in a suppression hearing before the presiding judge. This hearing is conducted before trial to determine what evidence will be suppressed or excluded from trial.