Which landmark case is known for establishing the exclusionary rule?

The landmark case that established the exclusionary rule is Mapp v. Ohio. This case, decided in 1961, emphasized the principle that evidence obtained in violation of the Fourth Amendment, which protects against unreasonable searches and seizures, cannot be used in state courts.

The exclusionary rule acts as a safeguard against illegal police conduct and is critical in maintaining the integrity of the judicial process. In Mapp v. Ohio, the Supreme Court held that not only federal courts, but also state courts must adhere to this rule, thereby extending the protection of the Fourth Amendment to all levels of the judiciary. This decision underscored the necessity of ensuring that law enforcement officers respect constitutional rights, reinforcing the idea that violating those rights has significant repercussions for the admissibility of evidence in court.

The other cases listed, while significant in their own contexts, do not pertain to the establishment of the exclusionary rule. For instance, Miranda v. Arizona focuses on the right to counsel and the requirement that individuals in police custody be informed of their rights, Terry v. Ohio deals with stop-and-frisk procedures and reasonable suspicion, and Gideon v. Wainwright addresses the right to free legal counsel in criminal cases. Each of these cases impacts various aspects