Which USSC case from 1961 established the Exclusionary Rule in state courts?

The case that established the Exclusionary Rule in state courts is Mapp v. Ohio. This landmark Supreme Court decision determined that evidence obtained in violation of the Fourth Amendment, which protects against unreasonable searches and seizures, cannot be used in state criminal prosecutions. The ruling extended the Exclusionary Rule, which had originally applied only to federal cases, to state courts, ensuring that defendants in state criminal cases have the same protections as those in federal cases.

Mapp v. Ohio was significant because it reinforced the necessity of upholding constitutional rights regarding search and seizure at all levels of law enforcement, promoting the integrity of the judicial system and discouraging unlawful police practices. The case arose from the fact that police officers entered Dollree Mapp's home without a warrant and found evidence that led to her conviction. The Supreme Court ultimately ruled that the search was unconstitutional, thus applying the Exclusionary Rule at both federal and state levels.