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Cite as: 524 U. S. 357 (1998)

363

Opinion of the Court

(White, J., dissenting)). The exclusionary rule is instead a
judicially created means of deterring illegal searches and sei-
zures. United States v. Calandra, 414 U. S. 338, 348 (1974).
As such, the rule does not “proscribe the introduction of
illegally seized evidence in all proceedings or against all
persons,” Stone v. Powell, supra, at 486, but applies only in
contexts “where its remedial objectives are thought most
efﬁcaciously served,” United States v. Calandra, supra, at
348; see also United States v. Janis, 428 U. S. 433, 454 (1976)
(“If . . . the exclusionary rule does not result in appreciable
deterrence, then, clearly, its use in the instant situation is
unwarranted”). Moreover, because the rule is prudential
rather than constitutionally mandated, we have held it to be
applicable only where its deterrence beneﬁts outweigh its
“substantial social costs.” United States v. Leon, 468 U. S.,
at 907.

Recognizing these costs, we have repeatedly declined to
extend the exclusionary rule to proceedings other than crim-
inal trials.
Id., at 909; United States v. Janis, supra, at 447.
For example, in United States v. Calandra, we held that the
exclusionary rule does not apply to grand jury proceedings;
in so doing, we emphasized that such proceedings play a spe-
cial role in the law enforcement process and that the tradi-
tionally ﬂexible, nonadversarial nature of those proceedings
414 U. S.,
would be jeopardized by application of the rule.
at 343–346, 349–350. Likewise, in United States v. Janis,
we held that the exclusionary rule did not bar the introduc-
tion of unconstitutionally obtained evidence in a civil tax pro-
ceeding because the costs of excluding relevant and reliable
evidence would outweigh the marginal deterrence beneﬁts,
which, we noted, would be minimal because the use of the
exclusionary rule in criminal trials already deterred illegal
searches.
428 U. S., at 448, 454. Finally, in INS v. Lopez-
Mendoza, 468 U. S. 1032 (1984), we refused to extend the
exclusionary rule to civil deportation proceedings, citing the
high social costs of allowing an immigrant to remain illegally