http://www.law.cornell.edu/supct/html/07-513.ZO.htmlJustice Ginsburg explains:
Petitioner Bennie Dean Herring was arrested, and subjected to a search incident to his arrest, although no warrant was outstanding against him, and the police lacked probable cause to believe he was engaged in criminal activity. The arrest and ensuing search therefore violated Herring’s Fourth Amendment right “to be secure … against unreasonable searches and seizures.” The Court of Appeals so determined, and the Government does not contend otherwise. The exclusionary rule provides redress for Fourth Amendment violations by placing the government in the position it would have been in had there been no unconstitutional arrest and search. The rule thus strongly encourages police compliance with the Fourth Amendment in the future. The Court, however, holds the rule inapplicable because careless recordkeeping by the police—not flagrant or deliberate misconduct—accounts for Herring’s arrest.
Negligent recordkeeping errors by law enforcement threaten individual liberty, are susceptible to deterrence by the exclusionary rule, and cannot be remedied effectively through other means. Such errors present no occasion to further erode the exclusionary rule. The rule “is needed to make the Fourth Amendment something real; a guarantee that does not carry with it the exclusion of evidence obtained by its violation is a chimera.”
Roberts, C. J., delivered the opinion of the Court, in which Scalia, Kennedy, Thomas, and Alito, JJ., joined. Ginsburg, J., filed a dissenting opinion, in which Stevens, Souter, and Breyer, JJ., joined. Breyer, J., filed a dissenting opinion, in which Souter, J., joined.