What principle did Mapp v. Ohio establish regarding evidence?

Mapp v. Ohio established the principle that evidence obtained through illegal means, specifically through violations of the Fourth Amendment rights against unreasonable searches and seizures, cannot be used in state courts. This landmark case extended the exclusionary rule, which was already applied at the federal level, to state law enforcement. The ruling emphasized that safeguarding individual rights against unlawful search and seizure is fundamental to ensuring justice and fairness in the legal system. As a result, evidence that is found to be illegally obtained is inadmissible in court, reinforcing the importance of lawful procedures in the collection of evidence.