374 U.S. 23 (1963), argued 11 Dec. 1962, decided 10 June 1963 by vote of 5 to 4; Clark for the Court, Harlan concurring in the result, Brennan dissenting in part joined by Warren, Douglas, and Goldberg. When the Court decided in Mapp v. Ohio (1961) to impose the exclusionary rule of the Fourth Amendment on the states through the Fourteenth Amendment, it was unclear to what extent federal standards of what constitutes unreasonable searches and seizures were applicable to the states. A case involving the marijuana dealings of George and Diane Ker resolved this issue. Reviewing their convictions, a consensus of eight justices agreed that the states were to be held to federal standards. The ninth justice, John M. Harlan, argued that states should be judged by a more flexible concept of fundamental fairness. The consensus, however, broke down in applying the principle to the facts of the case. A plurality of four justices found that the actions of the California authorities who had entered the Kers’ apartment with a passkey and without a warrant and who seized marijuana used to convict them met federal standards of probable cause and reasonableness. Justice Harlan concurred only in affirming the convictions. The four justices in dissent argued that the arrests and subsequent seizure were illegal because in their view the unannounced entry into the apartment was unjustified.
Ker remains a very important component of the exclusionary rule. The doctrine that Fourth Amendment (i.e., federal) standards of reasonableness apply to the states through the Fourteenth Amendment is still controlling law. But the holding that an unannounced warrantless entry to a person's home is valid is inconsistent with subsequent Court rulings such as Payton v. New York (1980). However, in Wilson v. Arkansas (1995), the Rehnquist Court held that police are ordinarily required to knock and announce their presence before entering a house to execute a search warrant, but that there may be “reasonable” exceptions to the rule to account for a likelihood of violence or imminent destruction of evidence.