Mapp v. Ohio

Police forced their way into Mapp's (defendant) home without a warrant while searching for a bombing suspect. When Mapp demanded a warrant, officers showed her a paper she grabbed and struggled to keep; the paper was never used as evidence. The search continued and turned up obscene materials, for which Mapp was convicted after refusing to testify against co-conspirators.

Whether the exclusionary rule applies to the states, requiring suppression of the evidence.