Knock-and-Announce Supreme Court Case Law
In Hudson v. Michigan (2006) 547 U.S. 586, the United States Supreme Court confronted the question of "whether the exclusionary rule is appropriate for violation of the knock-and-announce requirement." (Id. at p. 590.)
A majority of the court concluded that "the social costs of applying the exclusionary rule to knock-and-announce violations are considerable; the incentive to such violations is minimal to begin with, and the extant deterrences against them are substantial--incomparably greater than the factors deterring warrantless entries when Mapp v. Ohio (1961) 367 U.S. 643 was decided. Resort to the massive remedy of suppressing evidence of guilt is unjustified." (Hudson, at p. 599.)
Justice Scalia wrote the main opinion, which consisted of four parts. (Hudson v. Michigan, supra, 547 U.S. at pp. 588-602.)
Justices Breyer, Stevens, Souter, and Ginsburg dissented. (Id. at p. 604.)
Justice Kennedy declined to join part IV of Justice Scalia's opinion, but concurred in the judgment and joined in parts I through III, noting that "the Court's holding is fully supported by" those parts. (Id. at p. 604.)
Justice Kennedy specifically described the court's holding as follows: "In the specific context of the knock-and-announce requirement, a violation is not sufficiently related to the later discovery of evidence to justify suppression." (Id. at p. 603.)
Thus, five justices joined the ruling that the exclusionary rule is not available as a remedy for a violation of the knock-and-announce requirement.