Of course, the State or the Federal Government may provide alternative remedies for knock-and-announce violations. But that circumstance was true of Mapp as well. What reason is there to believe that those remedies (such as private damages actions under 42 U. S. C. §1983), which the Court found inadequate in Mapp, can adequately deter unconstitutional police behavior here? See Kamisar, In Defense of the Search and Seizure Exclusionary Rule, 26 Harv. J. L. & Pub. Pol’y 119, 126–129 (2003) (arguing that “five decades of post-Weeks ‘freedom’ from the inhibiting effect of the federal exclusionary rule failed to produce any meaningful alternative to the exclusionary rule in any jurisdiction” and that there is no evidence that “times have changed” post-Mapp).
The cases reporting knock-and-announce violations are legion. See, e.g., 34 Geo. L. J. Ann. Rev. Crim. Proc. 31–35 (2005) (collecting court of appeals cases); Annot., 85 A. L. R. 5th 1 (2001) (collecting state-court cases); Brief for Petitioner 16–17 (collecting federal and state cases). Indeed, these cases of reported violations seem sufficiently frequent and serious as to indicate “a widespread pattern.” Ante, at 2 (Kennedy, J., concurring in part and concurring in judgment).Yet the majority, like Michigan and the United States, has failed to cite a single reported case in which a plaintiff has collected more than nominal damages solely as a result of a knock-and-announce violation. Even Michigan concedes that, “in cases like the present one … , damages may be virtually non-existent.” Brief for Respondent 35, n. 66; And Michigan’s amici further concede that civil immunities prevent tort law from being an effective substitute for the exclusionary rule at this time. Brief for Criminal Justice Legal Foundation 10; see also Hope v. Pelzer, 536 U. S. 730, 739 (2002) (difficulties of overcoming qualified immunity defenses).
As Justice Stewart, the author of a number of significant Fourth Amendment opinions, explained, the deterrent effect of damage actions “can hardly be said to be great,” as such actions are “expensive, time-consuming, not readily available, and rarely successful.” Stewart, The Road to Mapp v. Ohio and Beyond: The Origins, Development and Future of the Exclusionary Rule in Search-and-Seizure Cases, 83 Colum. L. Rev. 1365, 1388 (1983). The upshot is that the need for deterrence—the critical factor driving this Court’s Fourth Amendment cases for close to a century—argues with at least comparable strength for evidentiary exclusion here.
To argue, as the majority does, that new remedies, such as 42 U. S. C. §1983 actions or better trained police, make suppression unnecessary is to argue that Wolf, not Mapp, is now the law. (The Court recently rejected a similar argument in Dickerson v. United States, 530 U. S. 428, 441–442 (2000) .) To argue that there may be few civil suits because violations may produce nothing “more than nominal injury” is to confirm, not to deny, the inability of civil suits to deter violations. See ante, at 11. And to argue without evidence (and despite myriad reported cases of violations, no reported case of civil damages, and Michigan’s concession of their nonexistence) that civil suits may provide deterrence because claims may “have been settled” is, perhaps, to search in desperation for an argument. See ibid. Rather, the majority, as it candidly admits, has simply “assumed” that, “[a]s far as [it] know, civil liability is an effective deterrent,” ibid., a support-free assumption that Mapp and subsequent cases make clear does not embody the Court’s normal approach to difficult questions of Fourth Amendment law.