David Carn

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In Hudson v. Michigan, the United States Supreme Court held in a 5-4 decision that evidence discovered by police after a knock-and-announce violation will not necessarily be excluded in court. The majority opinion, written by Justice Scalia, stated that exclusion is only appropriate where the interests protected by the knock-and-announce requirement are implicated and that hiding evidence from the government is not one of those interests. The Court further held that the substantial social costs of excluding evidence discovered upon knock-and-announce violations outweigh the deterrent effects of the exclusionary rule against police misconduct and, therefore, the application of the exclusionary rule against knock-and-announce violations is unjustified.

The dissent, written by Justice Breyer, claimed that the majority relied on misunderstandings of law and strongly asserted that exclusion of evidence is, and has always been, the only effective deterrent against knock-and-announce violations. Justice Kennedy concurred in part and in the judgment, but expressed reservations that a demonstration of a widespread pattern of knock-and-announce violations would be cause for grave concern.

The decision has important implications for both the government and citizens. On the one hand, less incriminating evidence will be excluded at trial. But on the other hand, there is a possibility that Fourth Amendment rights will be completely disregarded at the doors of both criminals and those innocently implicated in a necessarily imperfect law enforcement system.