What legal principle was established in Mapp v. Ohio?

In Mapp v. Ohio, the legal principle established is the exclusionary rule, which dictates that evidence obtained through illegal searches and seizures cannot be used in court. This landmark ruling applied the exclusionary rule to state courts, reinforcing the Fourth Amendment's protection against unreasonable searches and seizures at both the state and federal levels.

By determining that evidence obtained in violation of the Constitution cannot be admitted, the case underscored the importance of constitutional rights in legal proceedings. This decision helped ensure that law enforcement adheres to legal protocols when gathering evidence, thereby protecting citizens' rights and maintaining the integrity of the judicial system.

The other options reflect different aspects of legal standards or concepts, but they do not encapsulate the primary significance of Mapp v. Ohio as clearly as the exclusionary rule does.