SUPREME COURT OF THE UNITED STATES
BOOKER T. HUDSON, J r
on writ of certiorari to the court of appeals
[June 15, 2006]
, with whom J ustice
Stevens, Justice Souter
, and Justice Ginsburg
Arkansas, 514 U.S.
(1995), a unanimous Court held that the Fourth Amendment
normally requires law enforcement officers to knock and announce
their presence before entering a dwelling. Today's opinion holds
that evidence seized from a home following a violation of this
requirement need not be suppressed
As a result, the Court destroys the strongest legal incentive to
comply with the Constitution's knock-and-announce requirement. And
the Court does so without significant support in precedent. At
least I can find no such support in the many Fourth Amendment cases
the Court has decided in the near century since it first set forth
the exclusionary principle in Weeks
States, 232 U.S.
(1914). See Appendix, infra
Today's opinion is thus doubly troubling. It represents a
significant departure from the Court's precedents. And it weakens,
perhaps destroys, much of the practical value of the Constitution's
This Court has set forth the legal principles
that ought to have determined the outcome of this case in two sets
of basic Fourth Amendment cases. I shall begin by describing that
underlying case law.
The first set of cases describes the
constitutional knock-and-announce requirement, a requirement that
this Court initially set forth only 11 years ago in Wilson
. Cf. Sabbath
States, 391 U.S.
(1968) (suppressing evidence seized in violation of federal
statutory knock-and-announce requirement); Miller
United States, 357 U.S.
(1958) (same). In Wilson
, tracing the lineage of the
knock-and-announce rule back to the 13th century, 514 U. S., at
932, we wrote that
"[a]n examination of the common law of search
and seizure leaves no doubt that the reasonableness of a search of
a dwelling may depend in part on whether law enforcement officers
announced their presence and authority prior to entering."
., at 931.
We noted that this "basic principle" was agreed
upon by "[s]everal prominent founding-era commentators,"
, at 932, and "was woven quickly into the fabric of early
American law" via state constitutions and statutes, id
933. We further concluded that there was
"little doubt that the Framers of the Fourth
Amendment thought that the method of an officer's entry into a
dwelling was among the factors to be considered in assessing the
reasonableness of a search or seizure." Id
., at 934.
And we held that the "common-law 'knock and
announce' principle forms a part of the reasonableness inquiry
under the Fourth Amendment." Id
., at 929. Thus, "a search or
seizure of a dwelling might be constitutionally defective if police
officers enter without prior announcement." Id.
, at 936; see
, 540 U.S. 31, 36 (2003);
, 523 U.S.
, 70 (1998); Richards
, 520 U.S.
, 387 (1997).
The second set of cases sets forth certain
well-established principles that are relevant here. They
v. United States, 116 U.S.
(1886). In this seminal Fourth Amendment case, decided 120
years ago, the Court wrote, in frequently quoted language, that the
Fourth Amendment's prohibitions apply
"to all invasions on the part of the government
and its employés of the sanctity of a man's home and the
privacies of life. It is not the breaking of his doors, and the
rummaging of his drawers, that constitutes the essence of the
offence; but it is the invasion of his indefeasible right of
personal security, personal liberty and private property."
., at 630.
This case, decided
28 years after Boyd
, originated the exclusionary rule. The
Court held that the Federal Government could not retain evidence
seized unconstitutionally and use that evidence in a federal
criminal trial. The Court pointed out that "[i]f letters and
private documents" could be unlawfully seized from a home "and used
in evidence against a citizen accused of an offense, the protection
of the Fourth Amendment declaring his right to be secure against
such searches and seizures is of no value, and ... might as well be
stricken from the Constitution." 232 U. S., at 393.
Silverthorne Lumber Co.
States, 251 U.S.
(1920). This case created an exception to (or a
qualification of) Weeks
' exclusionary rule. The Court held
that the Government could not use information obtained during an
illegal search to subpoena documents that they illegally viewed
during that search. Writing for the Court, Justice Holmes noted
that the exclusionary rule "does not mean that the facts
[unlawfully] obtained become sacred and inaccessible. If knowledge
of them is gained from an independent source they may be proved
like any others ... ." 251 U. S., at 392. Silverthorne
stands for the proposition that the exclusionary rule does not
apply if the evidence in question (or the "fruits" of that
evidence) was obtained through a process unconnected with, and
untainted by, the illegal search. Cf. Nix
Williams, 467 U.S.
, 444 (1984) (describing related "inevitable discovery"
v. Colorado, 338 U.S.
(1949), and Mapp
v. Ohio, 367
(1961). Both of these cases considered whether
' exclusionary rule applies to the States. In
, the Court held that it did not. It said that "[t]he
security of one's privacy against arbitrary intrusion by the police
... is ... implicit in 'the concept of ordered liberty' and as such
enforceable against the States through the Due Process Clause." 338
U. S., at 27-28. But the Court held that the exclusionary rule is
not enforceable against the States as "an essential ingredient of
the right." Id.
, at 29. In Mapp
, the Court overruled
. Experience, it said, showed that alternative methods
of enforcing the Fourth Amendment's requirements had failed. See
367 U. S., at 651-653; see, e.g.
44 Cal. 2d 434
, 447, 282 P.2d 905, 913 (1955) (Traynor, C. J.)
("Experience [in California] has demonstrated, however, that
neither administrative, criminal nor civil remedies are effective
in suppressing lawless searches and seizures"). The Court
consequently held that "all evidence obtained by searches and
seizures in violation of the Constitution is, by that same
authority, inadmissible in a state court." Mapp
, 367 U. S.,
at 655. "To hold otherwise," the Court added, would be "to grant
the right but in reality to withhold its privilege and enjoyment."
, at 656.
Reading our knock-and-announce cases, Part I-A,
, in light of this foundational Fourth Amendment case
law, Part I-B, supra
, it is clear that the exclusionary rule
should apply. For one thing, elementary logic leads to that
conclusion. We have held that a court must "conside[r]" whether
officers complied with the knock-and-announce requirement "in
assessing the reasonableness of a search or seizure."
, 514 U. S., at 934 (emphasis added); see
, 540 U. S., at 36. The Fourth Amendment insists that
an unreasonable search or seizure is, constitutionally speaking, an
illegal search or seizure. And ever since Weeks
to federal prosecutions) and Mapp
(in respect to state
prosecutions), "the use of evidence secured through an illegal
search and seizure" is "barred" in criminal trials. Wolf
, at 28 (citing Weeks
); see Mapp
, at 655.
For another thing, the driving legal purpose
underlying the exclusionary rule, namely, the deterrence of
unlawful government behavior, argues strongly for suppression. See
v. United States, 364
, 217 (1960) (purpose of the exclusionary rule is "to
deter--to compel respect for the constitutional guaranty ... by
removing the incentive to disregard it"). In Weeks
, and Mapp
, the Court based its holdings
requiring suppression of unlawfully obtained evidence upon the
recognition that admission of that evidence would seriously
undermine the Fourth Amendment's promise. All three cases
recognized that failure to apply the exclusionary rule would make
that promise a hollow one, see Mapp
, at 657,
reducing it to "a form of words," Silverthorne
at 392, "of no value" to those whom it seeks to
, at 393. Indeed, this Court in
held that the exclusionary rule applies to the States
in large part due to its belief that alternative state mechanisms
for enforcing the Fourth Amendment's guarantees had proved
"worthless and futile." 367 U. S., at 652.
Why is application of the exclusionary rule any the less
necessary here? Without such a rule, as in Mapp
, police know
that they can ignore the Constitution's requirements without
risking suppression of evidence discovered after an unreasonable
entry. As in Mapp
, some government officers will find it
easier, or believe it less risky, to proceed with what they
consider a necessary search immediately and without the requisite
constitutional (say, warrant or knock-and-announce) compliance. Cf.
Mericli, The Apprehension of Peril Exception to the Knock and
Announce Rule--Part I, 16 Search and Seizure L. Rep. 129, 130
(1989) (hereinafter Mericili) (noting that some "[d]rug enforcement
authorities believe that safety for the police lies in a swift,
surprising entry with overwhelming force--not in announcing their
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
, 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
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
The cases reporting knock-and-announce violations are legion.
, 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
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
Pelzer, 536 U.S.
, 739 (2002) (difficulties of overcoming qualified immunity
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
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
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,
the law. (The Court recently rejected a similar argument in
v. United States, 530 U.S.
, 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
"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[s], 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.
It is not surprising, then, that after looking at virtually
every pertinent Supreme Court case decided since Weeks
can find no precedent that might offer the majority support for its
contrary conclusion. The Court has, of course, recognized that not
every Fourth Amendment violation necessarily triggers the
exclusionary rule. Ante
, at 4-5; cf. Illinois
, 462 U.S.
, 223 (1983) (application of the exclusionary rule is a
separate question from whether the Fourth Amendment has been
violated). But the class of Fourth Amendment violations that do not
result in suppression of the evidence seized, however, is
The Court has declined to apply the exclusionary rule only:
(1) where there is a specific reason to believe
that application of the rule would "not result in appreciable
deterrence," United States
, 428 U.S.
, 454 (1976); see, e.g.
, United States
, 468 U.S.
, 919-920 (1984) (exception where searching officer executes
defective search warrant in "good faith"); Arizona
, 514 U.S.
, 14 (1995) (exception for clerical errors by court
v. United States
, 347 U.S.
(1954) (exception for impeachment purposes), or
(2) where admissibility in proceedings other than criminal
trials was at issue, see, e.g.
, Pennsylvania Bd. of
Probation and Parole
, 364 (1998) (exception for parole revocation
, 468 U.S.
, 1050 (1984) (plurality opinion) (exception for
deportation proceedings); Janis
, at 458
(exception for civil tax proceedings); United States
, 414 U.S.
, 348-350 (1974) (exception for grand jury proceedings);
, 428 U.S.
, 493-494 (1976) (exception for federal habeas
Neither of these two exceptions applies here.
The second does not apply because this case is an ordinary criminal
trial. The first does not apply because (1) officers who violate
the rule are not acting "as a reasonable officer would and should
act in similar circumstances," Leon, supra,
at 920, (2) this
case does not involve government employees other than police,
, and (3), most importantly, the key
rationale for any exception, "lack of deterrence," is missing, see
Pennsylvania Bd. of Probation, supra
, at 364 (noting that
the rationale for not applying the rule in noncriminal cases has
been that the deterrence achieved by having the rule apply in those
contexts is "minimal" because
"application of the rule in
the criminal trial context already provides significant deterrence
of unconstitutional searches"); Michigan
Tucker, 417 U.S.
, 447 (1974) (noting that deterrence rationale would not be
served if rule applied to police officers acting in good faith, as
the "deterrent purpose of the exclusionary rule necessarily assumes
that the police have engaged in willful, or at the very least
negligent, conduct"). That critical latter rationale, which
exception, does not apply here, as there is
no reason to think that, in the case of knock-and-announce
violations by the police, "the exclusion of evidence at trial would
not sufficiently deter future errors," Evans
at 14, or "5 5'further the ends of the exclusionary rule in any
appreciable way,'5 5" Leon
, at 919-920.
I am aware of no other basis for an exception. The Court has
decided more than 300 Fourth Amendment cases since Weeks
The Court has found constitutional violations in nearly a third of
them. See W. Greenhalgh, The Fourth Amendment Handbook: A
Chronological Survey of Supreme Court Decisions 27-130 (2d ed.
2003) (collecting and summarizing 332 post-Weeks
decided between 1914 and 2002). The nature of the constitutional
violation varies. In most instances officers lacked a warrant; in
others, officers possessed a warrant based on false affidavits; in
still others, the officers executed the search in an
unconstitutional manner. But in every case involving evidence
seized during an illegal search of a home (federally since
, nationally since Mapp
), the Court, with the
exceptions mentioned, has either explicitly or implicitly upheld
(or required) the suppression of the evidence at trial. See
. In not one of those cases did the Court
"questio[n], in the absence of a more efficacious sanction, the
continued application of the [exclusionary] rule to suppress
evidence from the State's case" in a criminal trial. Franks
, 171 (1978).
I can find nothing persuasive in the majority's opinion that
could justify its refusal to apply the rule. It certain- ly is not
a justification for an exception here (as the majority finds) to
find odd instances in other
areas of law that do not
automatically demand suppression. Ante
, at 10 (suspect
confesses, police beat him up afterwards;
police apparently arrest him, take him to
station, and refuse to tell him of his right to counsel). Nor can
it justify an exception to say that some
police may knock at
the door anyway (to avoid being mistaken for a burglar), for other
police (believing quick entry is the most secure, effective entry)
will not voluntarily do so. Cf. Mericli 130 (describing Special
Weapons and Tactics (SWAT) team practices); R. Balko, No SWAT (Apr.
6, 2006), available at
http://www.cato.org/pub_display.php?pub_id=6344 (all Internet
materials as visited June 7, 2006, and available in Clerk of
Court's case file).
Neither can the majority justify its failure to respect the need
for deterrence, as set forth consistently in the Court's prior case
law, through its claim of "substantial social costs"--at least if
it means that those "social costs" are somehow special here. The
only costs it mentions are those that typically accompany
use of the Fourth Amendment's exclusionary principle:
(1) that where the constable blunders, a guilty defendant may be
set free (consider Mapp
itself); (2) that defendants may
assert claims where Fourth Amendment rights are uncertain (consider
the Court's qualified immunity jurisprudence), and (3) that
sometimes it is difficult to decide the merits of those uncertain
claims. See ante
, at 8-9. In fact, the "no-knock" warrants
that are provided by many States, by diminishing uncertainty, may
make application of the knock-and-announce principle less
"cost[ly]" on the whole than application of comparable Fourth
Amendment principles, such as determining whether a particular
warrantless search was justified by exigency. The majority's
"substantial social costs" argument is an argument against the
Fourth Amendment's exclusionary principle itself. And it is an
argument that this Court, until now, has consistently rejected.
The majority, Michigan, and the United States
make several additional arguments. In my view, those arguments rest
upon misunderstandings of the principles underlying this Court's
The majority first argues that "the
constitutional violation of an illegal manner
of entry was
a but-for cause of obtaining the evidence." Ante
at 5. But taking causation as it is commonly understood in the law,
I do not see how that can be so. See W. Keeton, D. Dobbs, R.
Keeton, & D. Owen, Prosser and Keeton on Law of Torts 266 (5th
ed. 1984). Although the police might have entered Hudson's home
lawfully, they did not in fact do so. Their unlawful behavior
inseparably characterizes their actual entry; that entry was a
necessary condition of their presence in Hudson's home; and their
presence in Hudson's home was a necessary condition of their
finding and seizing the evidence. At the same time, their discovery
of evidence in Hudson's home was a readily foreseeable consequence
of their entry and their unlawful presence within the home. Cf. 2
Restatement (Second) of Torts §435 (1963-1964).
Moreover, separating the "manner of entry" from
the related search slices the violation too finely. As noted, Part
, we have described a failure to comply with the
knock-and-announce rule, not as an independently unlawful event,
but as a factor that renders the search
, 514 U. S., at 936; see also id
at 934 (compliance with the knock-and-announce requirement is one
of the "factors to be considered in assessing the reasonableness
of a search or seizure
" (emphasis added)); Ker
California, 374 U.S.
, 53 (1963) (opinion of Brennan, J.) ("[A] lawful entry is
the indispensable predicate of a reasonable search").
The Court nonetheless accepts Michigan's argument that the
requisite but-for-causation is not satisfied in this case because,
whether or not the constitutional violation occurred (what the
Court refers to as a "preliminary misstep"), "the police would have
executed the warrant they had obtained, and would have discovered
the gun and drugs inside the house." Ante
, at 5. As support
for this proposition, Michigan rests on this Court's inevitable
This claim, however, misunderstands the inevitable discovery
doctrine. Justice Holmes in Silverthorne
, in discussing an
"independent source" exception, set forth the principles underlying
the inevitable discovery rule. See supra
, at 4. That rule
does not refer to discovery that would have taken place if the
police behavior in question had (contrary to fact) been lawful. The
doctrine does not treat as critical what hypothetically
have happened had the police acted lawfully in the first
place. Rather, "independent" or "inevitable" discovery refers to
discovery that did occur or that would have occurred (1)
(not simply in the absence of
) the unlawful
behavior and (2) independently
of that unlawful behavior.
The government cannot, for example, avoid suppression of evidence
seized without a warrant (or pursuant to a defective warrant)
simply by showing that it could have obtained a valid warrant had
it sought one. See, e.g.
, 403 U.S.
, 450-451 (1971). Instead, it must show that the same
evidence "inevitably would
have been discovered by lawful
, 467 U. S., at 444
(emphasis added). "What a man could
do is not at all the
same as what he would
do." Austin, Ifs And Cans, 42
Proceedings of the British Academy 109, 111-112 (1956).
The inevitable discovery exception rests upon the principle that
the remedial purposes of the exclusionary rule are not served by
suppressing evidence discovered through a "later, lawful
seizure" that is "genuinely independent
of an earlier,
tainted one." Murray
v. United States, 487 U.S.
, 542 (1988) (emphasis added); see also id
., at 545
(Marshall, J., joined by S tevens
and O'Connor, JJ.,
dissenting) ("When the seizure of the evidence at issue is 'wholly
independent of' the constitutional violation, then exclusion
arguably will have no effect on a law enforcement officer's
incentive to commit an unlawful search").
Case law well illustrates the meaning of this principle. In
, police officers violated a defendant's
Sixth Amendment right by eliciting incriminating statements from
him after he invoked his right to counsel. Those statements led to
the discovery of the victim's body. The Court concluded that
evidence obtained from the victim's body was admissible because it
would ultimately or inevitably have been discovered by a volunteer
search party effort that was ongoing--whether or not the Sixth
Amendment violation had taken place. Id
., at 449. In other
words, the evidence would have been found despite
, the Sixth Amendment violation.
v. United States
, 468 U.S.
(1984), one of the "trio of cases" Justice Scalia
says "confirms [the Court's] conclusion," ante
, at 13, the
Court held that an earlier illegal entry into an apartment did not
require suppression of evidence that police later seized when
executing a search warrant obtained on the basis of information
unconnected to the initial entry. The Court reasoned that the
"evidence was discovered the day following the entry, during the
search conducted under a valid warrant
, a warrant
obtained independently without use of any information found during
the illegal entry--and that "it was the product of that
search, wholly unrelated to the prior [unlawful] entry."
, at 814 (emphasis added).
, the Court upheld the
admissibility of seized evidence where agents entered a warehouse
without a warrant, and then later returned with a valid warrant
that was not obtained on the basis of evidence observed during the
first (illegal) entry. The Court reasoned that while the agents'
"[k]nowledge that the marijuana was in the warehouse was assuredly
acquired at the time of the unlawful entry ... it was also
acquired at the time of entry pursuant to the warrant, and if
that later acquisition was not the result of the earlier entry
there is no reason why the independent source doctrine should not
., at 541 (emphasis added).
Thus, the Court's opinion reflects a misunderstanding of what
"inevitable discovery" means when it says, "[i]n this case, of
course, the constitutional violation of an illegal manner
entry was not
a but-for cause of obtaining the evidence."
, at 5. The majority rests this conclusion on its next
statement: "Whether that preliminary misstep has occurred or
, the police ... would have discovered the gun and the drugs
inside the house." Ibid.
Despite the phrase "of course,"
neither of these statements is correct. It is not true that, had
the illegal entry not occurred, "police would have discovered the
guns and drugs inside the house." Without that unlawful entry they
would not have been inside the house; so there would have been no
discovery. See supra
, at 12.
Of course, had the police entered the house lawfully, they would
have found the gun and drugs. But that fact is beside the point.
The question is not what police might have done had they not
behaved unlawfully. The question is what they did do. Was there set
in motion an independent chain of events that would have inevitably
led to the discovery and seizure of the evidence despite, and
independent of, that behavior? The answer here is "no."
The majority, Michigan, and the United States
point out that the officers here possessed a warrant authorizing a
, at 5. That fact, they argue, means that the
evidence would have been discovered independently or somehow
diminishes the need to suppress the evidence. But I do not see why
that is so. The warrant in question was not a "no-knock" warrant,
which many States (but not Michigan) issue to assure police that a
prior knock is not necessary. Richards
, 520 U. S., at 396,
n. 7 (collecting state statutes). It did not authorize a search
that fails to comply with knock-and-announce requirements. Rather,
it was an ordinary search warrant. It authorized a search that
, not a search that disregarded
Constitution's knock-and-announce rule.
Would a warrant that authorizes entry into a
home on Tuesday permit the police to enter on Monday? Would a
warrant that authorizes entry during the day authorize the police
to enter during the middle of the night? It is difficult for me to
see how the presence of a warrant that does not authorize the entry
in question has anything to do with the "inevitable discovery"
exception or otherwise diminishes the need to enforce the
knock-and-announce requirement through suppression.
The majority and the United States set forth a
policy-related variant of the causal connection theme: The United
States argues that the law should suppress evidence only insofar as
a Fourth Amendment violation causes the kind of harm that the
particular Fourth Amendment rule seeks to protect against. It adds
that the constitutional purpose of the knock-and-announce rule is
to prevent needless destruction of property (such as breaking down
a door) and to avoid unpleasant surprise. And it concludes that the
exclusionary rule should suppress evidence of, say, damage to
property, the discovery of a defendant in an "intimate or
compromising moment," or an excited utterance from the occupant
caught by surprise, but nothing more. Brief for United States as
The majority makes a similar argument. It says
that evidence should not be suppressed once the causal connection
between unlawful behavior and discovery of the evidence becomes too
at 5. But the majority then makes clear
that it is not using the word "attenuated" to mean what this
Court's precedents have typically used that word to mean, namely,
that the discovery of the evidence has come about long after the
unlawful behavior took place or in an independent way, i.e.
through "5 5'means sufficiently distinguishable to be purged of the
primary taint.'5 5" Wong Sun
v. United States,
, 487-488 (1963); see Brown
Illinois, 422 U.S.
, 603-604 (1975).
Rather, the majority gives the word "attenuation" a new meaning
(thereby, in effect, making the same argument as the United
States). "Attenuation," it says, "also occurs when, even given a
direct causal connection, the interest protected by the
constitutional guarantee that has been violated would not be served
by suppression of the evidence obtained." Ante
, at 6. The
interests the knock-and-announce rule seeks to protect, the Court
adds, are "human life" (at stake when a householder is
"surprised"), "property" (such as the front door), and "those
elements of privacy and dignity that can be destroyed by a sudden
entrance," namely, "the opportunity to collect oneself before
answering the door." Ante
, at 7. Since none of those
interests led to the discovery of the evidence seized here, there
is no reason to suppress it.
There are three serious problems with this argument. First, it
does not fully describe the constitutional values, purposes, and
objectives underlying the knock-and-announce requirement. That rule
does help to protect homeowners from damaged doors; it does help to
protect occupants from surprise. But it does more than that. It
protects the occupants' privacy by assuring them that government
agents will not enter their home without complying with those
requirements (among others) that diminish the offensive nature of
any such intrusion. Many years ago, Justice Frankfurter wrote for
the Court that the "knock at the door, ... as a prelude to a
search, with-out authority of law ... [is] inconsistent with the
conception of human rights enshrined in [our] history" and
, 338 U. S., at 28. How much the more
offensive when the search takes place without any knock at all. Cf.
, 514 U. S., at 931 (knock-and-announce rule
recognizes that "the common law generally protected a man's house
as 'his castle of defence and asylum' " (quoting 3 W. Blackstone,
Commentaries *288)); Miller
, 357 U. S., at 313 (federal
knock-and-announce statute "codif[ied] a tradition embedded in
Anglo-American law" that reflected "the reverence of the law for
the individual's right of privacy in his house").
Over a century ago this Court wrote that "it is not the breaking
of his doors" that is the "essence of the offence," but the
"invasions on the part of the government ... of the sanctity of a
man's home and the privacies of life." Boyd
, 116 U. S., at
630. And just this Term we have reiterated that "it is beyond
dispute that the home is entitled to special protection as the
center of the private lives of our people." Georgia
, 547 U. S. ___, ___ (2006) (slip op., at 10)
, 525 U.S.
, 99 (1998) (K ennedy
, J., concurring)). The
knock-and-announce requirement is no less a part of the
"centuries-old principle" of special protection for the privacy of
the home than the warrant requirement. See 547 U. S., at ___ (slip
op., at 10) (citing Miller
at 307). The Court
is therefore wrong to reduce the essence of its protection to "the
right not to be intruded upon in one's nightclothes." Ante
at 10; see Richards
, 520 U. S., at 393, n. 5 ("[I]ndividual
privacy interest[s]" protected by the rule are "not
inconsequential" and "should not be unduly minimized").
Second, whether the interests underlying the knock-and-announce
rule are implicated in any given case is, in a sense, beside the
point. As we have explained, failure to comply with the
knock-and-announce rule renders the related search unlawful.
at 936. And where a search is
unlawful, the law insists upon suppression of the evidence
consequently discovered, even if that evidence or its possession
has little or nothing to do with the reasons underlying the
unconstitutionality of a search. The Fourth Amendment does not seek
to protect contraband, yet we have required suppression of
contraband seized in an unlawful search. See, e.g
v. United States
, 533 U.S.
, 40 (2001); Coolidge
, 403 U. S., at 473. That is
because the exclusionary rule protects more general "privacy values
through deterrence of future police misconduct." James
, 493 U.S.
, 319 (1990). The same is true here.
Third, the majority's interest-based approach departs from prior
law. Ordinarily a court will simply look to see if the
unconstitutional search produced the evidence. The majority does
not refer to any relevant case in which, beyond that, suppression
turned on the far more detailed relation between, say, (1) a
particular materially false statement made to the magistrate who
issued a (consequently) invalid warrant and (2) evidence found
after a search with that warrant. But cf. ante,
at 15, n. 2
(plurality opinion) (citing New York
Harris, 495 U.S.
(1990), as such a case in section of opinion that Justice
does not join). And the majority's failure does not
surprise me, for such efforts to trace causal connections at retail
could well complicate Fourth Amendment suppression law, threatening
The United States, in its brief and at oral
argument, has argued that suppression is "an especially harsh
remedy given the nature of the violation in this case." Brief for
United States as Amicus Curiae
28; see also id
24. This argument focuses upon the fact that entering a house after
knocking and announcing can, in some cases, prove dangerous to a
police officer. Perhaps someone inside has a gun, as turned out to
be the case here. The majority adds that police officers about to
encounter someone who may try to harm them will be "uncertain" as
to how long to wait. Ante
, at 9. It says that, "[i]f the
consequences of running afoul" of the knock-and-announce "rule were
so massive," i.e.
, would lead to the exclusion of evidence,
then "officers would be inclined to wait longer than the law
requires--producing preventable violence against officers in some
To argue that police efforts to assure
compliance with the rule may prove dangerous, however, is not to
argue against evidence suppression. It is to argue against the
validity of the rule itself. Similarly, to argue that enforcement
means uncertainty, which in turn means the potential for dangerous
and longer-than-necessary delay, is (if true) to argue against
meaningful compliance with the rule.
The answer to the first argument is that the rule itself does
not require police to knock or to announce their presence where
police have a "reasonable suspicion" that doing so "would be
dangerous or futile" or "would inhibit the effective investigation
of the crime by, for example, allowing the destruction of
, at 394; see Banks
540 U. S., at 36-37; Wilson
The answer to the second argument is that States can, and many
do, reduce police uncertainty while assuring a neutral evaluation
of concerns about risks to officers or the destruction of evidence
by permitting police to obtain a "no-knock" search warrant from a
magistrate judge, thereby assuring police that a prior announcement
is not necessary. Richards
, 520 U. S., at 396, n. 7
(collecting state statutes). While such a procedure cannot remove
all uncertainty, it does provide an easy way for officers to comply
with the knock-and-announce rule.
Of course, even without such a warrant, police maintain the
backup "authority to exercise independent judgment concerning the
wisdom of a no-knock entry at the time the warrant is being
. "[I]f circumstances support a reasonable
suspicion of exigency when the officers arrive at the door, they
may go straight in." Banks
, at 37. And
"[r]easonable suspicion is a less demanding standard than probable
cause ... ." Alabama
, 496 U.S.
, 330 (1990); see Terry
, 392 U.S.
, 21-22 (1968) (no Fourth Amendment violation under the
reasonable suspicion standard if "the facts available to the
officer at the moment of the seizure or the search 'warrant a man
of reasonable caution in the belief' that the action taken was
Consider this very case. The police obtained a search warrant
that authorized a search, not only for drugs, but also for
. App. 5. If probable cause justified a search for guns,
why would it not also have justified a no-knock warrant, thereby
diminishing any danger to the officers? Why (in a State such as
Michigan that lacks no-knock warrants) would it not have justified
the very no-knock entry at issue here? Indeed, why did the
prosecutor not argue in this very case that, given the likelihood
of guns, the no-knock entry was lawful? From what I have seen in
the record, he would have won. And had he won, there would have
been no suppression here.
That is the right way to win. The very process of arguing the
merits of the violation would help to clarify the contours of the
knock-and-announce rule, contours that the majority believes are
too fuzzy. That procedural fact, along with no-knock warrants, back
up authority to enter without knocking regardless, and use of the
"reasonable suspicion" standard for doing so should resolve the
government's problems with the knock-and-announce rule while
reducing the "uncertain[ty]" that the majority discusses to levels
beneath that found elsewhere in Fourth Amendment law (e.g.
exigent circumstances). Ante
, at 8. Regardless, if the Court
fears that effective enforcement of a constitutional requirement
will have harmful consequences, it should face those fears directly
by addressing the requirement itself. It should not argue, "the
requirement is fine, indeed, a serious matter, just don't enforce
It should be apparent by now that the three
cases upon which Justice Scalia
United States, 468 U.S.
; New York
v. Harris, 495 U.S.
; and Ramirez,
523 U. S. 65--do not support his
conclusion. See ante
, at 13-15. Indeed, Justice
declines to join this section of the lead opinion
because he fails to see the relevance of Segura
, though he does rely on Ramirez
at 3 (opinion concurring in part and concurring in judgment).
first argues that, if the
"search in Segura
could be 'wholly unrelated to the prior
entry, ... when the only entry was warrantless, it would be bizarre
to treat more harshly the actions in this case, where the only
entry was with
a warrant." Ante
, at 14. Then it says
that, "[i]f the probable cause backing a warrant that was issued
later in time
could be an 'independent source' for a search
that proceeded after the officers illegally entered and waited, a
search warrant obtained before
going in must have at least
this much effect." Ibid.
I do not understand these
arguments. As I have explained, the presence of a warrant that did
not authorize a search that fails to comply with knock-and-announce
requirements is beside the point. See Part III-B, supra
the timing of the warrant in Segura
made no difference to
the case. The relevant fact about the warrant there was that it was
lawfully obtained and arguably set off an independent chain of
events that led the police to seize the evidence. 468 U. S., at
814; see also id
., at 814-815 ("The valid warrant search was
a 'means sufficiently distinguishable' to purge the evidence of any
'taint' arising from the entry" (citations omitted)). As noted,
there is no such independent event, or intervening chain of events
that would purge the taint of the illegal entry, present here. See
, at 15. The search that produced the relevant evidence
here is the very search that the knock-and-announce violation
rendered unlawful. There simply is no "independent source."
As importantly, the Court in Segura
said nothing to
suggest it intended to create a major exclusionary rule exception,
notwithstanding the impact of such an exception on deterrence.
Indeed, such an exception would be inconsistent with a critical
rationale underlying the independent source and inevitable
discovery rules, which was arguably available in Segura
which is clearly absent here. That rationale concerns deterrence.
The threat of inadmissibility deters unlawful police behavior; and
the existence of an exception applicable where evidence is found
through an untainted independent route will rarely undercut that
deterrence. That is because the police can rarely rely upon such an
exception--at least not often enough to change the deterrence
calculus. See Murray
, 487 U. S., at 540 ("We see the
incentives differently. An officer with probable cause sufficient
to obtain a search warrant would be foolish to enter the premises
in an unlawful manner. By doing so, he would risk suppression of
all evidence on the premises ... "); Nix
, 467 U. S., at 445
("A police officer who is faced with the opportunity to obtain
evidence illegally will rarely, if ever, be in a position to
calculate whether the evidence sought would inevitably be
., at 444 ("If the prosecution can establish
by a preponderance of the evidence that the information ultimately
or inevitably would have been discovered by lawful means--here the
volunteers' search--then the deterrence rationale has so little
basis that the evidence should be received").
's police officers would have been foolish to have
entered the apartment unlawfully with the ex ante
an independent causal chain of events would later occur and render
admissible the evidence they found. By way of contrast, today's
holding will seriously undermine deterrence in knock-and-announce
cases. Officers will almost always know ex ante
can ignore the knock-and-announce requirement without risking the
suppression of evidence discovered after their unlawful entry. That
fact is obvious, and this Court has never before today--not in
or any other post-Weeks
case--refused to apply the exclusionary rule where its absence
would so clearly and so significantly impair government officials'
incentive to comply with comparable Fourth Amendment
Neither does New York
support the Court's result. See ante
, at 6, 14; but see
, at 3 (opinion of Kennedy
, J.) (declining to
join section relying on Harris
). In Harris
officers arrested the defendant at his home without a warrant, in
violation of Payton
v. New York
(1980). Harris made several incriminating statements:
a confession in his home, a written inculpatory statement at the
stationhouse, and a videotaped interview conducted by the district
attorney at the stationhouse. 495 U. S., at 16. The trial court
suppressed the statements given by Harris in the house and on the
videotape, and the State did not challenge either of those rulings.
. The sole question in the case was whether the written
statement given later at the stationhouse should also have been
suppressed. The Court held that this later, outside-the-home
statement "was admissible because Harris was in legal custody ...
and because the statement, while the product of an arrest and being
in custody, was not the fruit of the fact that the arrest was made
in the house rather than someplace else." Id
., at 20.
Immediately after the Court stated its holding, it explained:
"To put the matter another way, suppressing the
statement taken outside the house would not serve the purpose of
the rule that made Harris' in-house arrest illegal. The warrant
requirement for an arrest in the home is imposed to protect the
home, and anything incriminating the police gathered from arresting
Harris in his home, rather than elsewhere, has been excluded, as it
should have been;
the purpose of the rule has thereby been
How can Justice Scalia
maintain that the
evidence here--a gun and drugs seized in the home--is "5 5'not the
fruit'5 5" of the illegal entry? Ante
, at 14. The officers'
failure to knock and announce rendered the entire search unlawful,
, 514 U. S., at 936, and that unlawful search led to
the discovery of evidence in petitioner's home. Thus, Harris
compels the opposite result than that reached by the Court today.
Like the Payton
rule at issue in Harris
knock-and-announce rule reflects the "reverence of the law for the
individual's right of privacy in his house." Miller
, 357 U.
S., at 313; cf. Harris
, 495 U. S., at 17 ("Payton
itself emphasized that our holding in that case stemmed from the
'overriding respect for the sanctity of the home that has been
embedded in our traditions since the origins of the Republic'5 5").
Like the confession that was "excluded, as it should have been," in
., at 20, the evidence in this case was
seized in the home, immediately following the illegal entry. And
, nothing in petitioner's argument would require
the suppression of evidence obtained outside
following a knock-and-announce violation should be suppressed,
precisely because officers have a remaining incentive to follow the
rule to avoid the suppression of any evidence obtained from the
very place they are searching. Cf. ibid.
("Even though we
decline to suppress statements made outside the home following a
violation, the principle incentive to obey
still obtains: the police know that a warrantless
entry will lead to the suppression of any evidence found, or
statements taken, inside the home").
I concede that United States
, 523 U.S.
, offers the majority its last best hope. Ante,
14-15. But not even that case can offer the majority significant
support. The majority focuses on the Court's isolated statement
that "destruction of property in the course of a search may violate
the Fourth Amendment, even though the entry itself is lawful and
the fruits of the search are not subject to suppression
at 71 (emphasis added). But even if I
accept this dictum, the entry here is unlawful, not lawful.
, 514 U. S., at 931, 934. It is one thing to say (in
an appropriate case) that destruction of property after proper
entry has nothing to do with discovery of the evidence, and to
refuse to suppress. It would be quite another thing to say that
improper entry had nothing to do with discovery of the evidence in
this case. Moreover, the deterrence analysis for the property
destruction cases (where, by definition, there will almost always
be quantifiable damages) might well differ.
There is perhaps one additional argument
implicit in the majority's approach. The majority says, for
example, that the "cost" to a defendant of "entering this lottery,"
, of claiming a "knock-and-announce" violation, "would
be small, but the jackpot enormous"--namely, a potential
"get-out-of-jail-free card." Ante
, at 8. It adds that the
"social costs" of applying the exclusionary rule here are not worth
the deterrence benefits. Ante
, at 13. Leaving aside what I
believe are invalid arguments based on precedent or the majority's
own estimate that suppression is not necessary to deter
constitutional violations, one is left with a simple unvarnished
conclusion, namely, that in this kind of case, a knock-and-announce
case, "[r]esort to the massive remedy of suppressing evidence of
guilt is unjustified." Ibid.
Why is that judicial judgment,
taken on its own, inappropriate? Could it not be argued that the
knock-and-announce rule, a subsidiary Fourth Amendment rule, is
simply not important enough to warrant a suppression remedy? Could
the majority not simply claim that the suppression game is not
worth the candle?
The answer, I believe, is "no." That "no"
reflects history, a history that shows the knock-and-announce rule
is important. See Wilson
, at 931-936. That
"no" reflects precedent, precedent that shows there is no
pre-existing legal category of exceptions to the exclusionary rule
into which the knock-and-announce cases might fit. See
, at 8-9. That "no" reflects empirical fact, experience
that provides confirmation of what common sense suggests: without
suppression there is little to deter knock-and-announce violations.
, at 6-7.
There may be instances in the law where text or
history or tradition leaves room for a judicial decision that rests
upon little more than an unvarnished judicial instinct. But this is
not one of them. Rather, our Fourth Amendment traditions place high
value upon protecting privacy in the home. They emphasize the need
to assure that its constitutional protections are effective, lest
the Amendment 'sound the word of promise to the ear but break it to
the hope.' They include an exclusionary principle, which since
has formed the centerpiece of the criminal law's
effort to ensure the practical reality of those promises. That is
why the Court should assure itself that any departure from that
principle is firmly grounded in logic, in history, in precedent,
and in empirical fact. It has not done so. That is why, with
respect, I dissent.
APPENDIX TO OPINION OF BREYER, J.
Fourth Amendment decisions from 1914 to present
requiring suppression of evidence seized (or remanding for lower
court to make suppression determination) in a private home
following an illegal arrest or search:
v. United States,
(1914) (warrantless search)
v. United States, 255 U.S.
(1921) (warrantless arrest and search)
v. United States, 269 U.S.
(1925) (warrantless search)
v. United States, 273 U.S.
(1927) (invalid warrant)
5. United States
v. Berkeness, 275 U.S.
(1927) (invalid warrant; insufficient affidavit)
v. United States, 286 U.S. 1
(1932) (warrantless search)
v. United States, 287 U.S.
(1932) (invalid warrant; insufficient affidavit)
v. United States, 290 U.S.
(1933) (invalid warrant; insufficient affidavit)
v. United States, 335 U.S.
(1948) (warrantless arrest and search)
v. United States, 353 U.S.
(1957) (per curiam)
v. United States, 364 U.S.
(1960) (search beyond scope of warrant)
v. United States, 365 U.S.
(1961) (warrantless use of electronic device)
v. United States, 365 U.S.
(1961) (warrantless search)
v. Ohio, 367
(1961) (warrantless search)
15. Wong Sun
v. United States, 371 U.S.
(1963) (warrantless search and arrest)
v. Connecticut, 375 U.S.
(1963) (warrantless search)
v. Texas, 378
(1964) (invalid warrant; insufficient affidavit)
v. Texas, 379 U.S.
(1965) (invalid warrant; particularity defect)
v. Louisiana, 382 U.S.
(1965) (per curiam)
v. Virginia, 384 U.S.
(1966) (per curiam)
(invalid warrant; insufficient
v. North Carolina, 391 U.S.
(1968) (lack of valid consent to search)
v. City of Lorain, 393 U.S.
(1968) (per curiam)
v. California, 395 U.S.
(1969) (invalid search incident to arrest)
24. Von Cleef
v. New Jersey, 395 U.S.
(1969) (per curiam)
(invalid search incident to
v. California, 395 U.S.
(1969) (per curiam)
(invalid search incident to
v. Louisiana, 399 U.S.
(1970) (invalid search incident to arrest)
v. Georgia, 429 U.S.
(1977) (per curiam)
(invalid warrant; magistrate
judge not neutral)
v. Tyler, 436 U.S.
(1978) (warrantless search)
v. Arizona, 437 U.S.
(1978) (warrantless search)
v. Delaware, 438 U.S.
(1978) (invalid warrant; obtained through perjury)
v. New York, 445
(1980) (warrantless arrest)
v. United States, 451 U.S.
(1981) (warrantless search)
v. Clifford, 464 U.S.
(1984) (warrantless search)
v. Wisconsin, 466 U.S.
(1984) (warrantless entry into home without exigent
v. Louisiana, 469 U.S.
(1984) (per curiam)
v. Hicks, 480
(1987) (unreasonable search)
v. Olson, 495 U.S.
(1990) (warrantless entry into home)
v. West Virginia,
528 U.S. 11 (1999)
v. United States, 533 U.S.
(2001) (warrantless use of heat-imaging technology)
536 U.S. 635 (2002) (per
(warrantless arrest and search)
v. Texas, 538
(2003) (per curiam)