What is the exclusionary rule and which case established it for the states?

• A. Weeks v. United States
• B. Wolf v. Colorado
• C. Katz v. United States
• D. Mapp v. Ohio

Answer: (D)

The exclusionary rule says that evidence obtained through unlawful searches and seizures cannot be used in court, serving to deter police from violating the Fourth Amendment. Weeks v. United States established this rule for federal prosecutions. For applicability to the states, the key step is Mapp v. Ohio, where the Supreme Court held that the Fourth Amendment’s protections—and the exclusionary rule—apply to state and local law enforcement through incorporation of the Fourteenth Amendment. Katz v. United States focuses on privacy expectations, not the exclusion of evidence, and Wolf v. Colorado addressed the state issue before incorporation. Thus, the case that established the rule for the states is Mapp v. Ohio.