When Should Fourth Amendment Violations Lead to Suppression of Evidence? The Supreme Court Takes a "Knock and Announce" Case

The Supreme Court has held, in Wilson v. Arkansas, that when police enter a home, the Fourth Amendment ordinarily requires that they first knock and announce their purpose to the inhabitants. The reason for the requirement (which I will call "knock-and-announce") is to avoid the fear and unwarranted exposure occasioned by a surprise search. With a warning, residents know that they are not about to be robbed, and they might even have time to throw on a robe if they are undressed.

On occasion, "countervailing factors" will permit a no-knock entry into a home. In Richards v. Wisconsin, however, the Court specifically rejected an across-the-board exception to knock-and-announce for felony drug cases. If whole categories of cases were permitted to excuse the failure to knock-and-announce, the Court reasoned, then there would be little left to the rule.

The Court recently granted review in Hudson v. Michigan, a case that addresses the consequences of police violation of knock-and-announce. Specifically, the Court will consider whether evidence obtained after an illegal no-knock home entry should be admissible, across the board, on the theory that it would have been "inevitably discovered" if police had followed the rules.

The question provides an opportunity for the Court to consider the rationale behind the inevitable discovery doctrine, and whether it applies in the knock-and-announce context.

The Independent Source Doctrine: A Related Exception to the Exclusionary Rule

To understand inevitable discovery, it is useful first to consider a related exception to the Fourth Amendment exclusionary rule: the independent source doctrine.

In its most straightforward form, the independent source rule stands for an unremarkable proposition: If the police violate the Fourth Amendment to perform one search but conform their conduct to the demands of the Fourth Amendment in performing another search, then the fruits of the legal search do not become inadmissible by virtue of the illegal one. For two concededly separate events, this disposition makes perfect sense.

The independent source doctrine became more controversial, however, when the Supreme Court applied it to evidence that resulted from both a legal search and an illegal search. In Murray v. United States, the Court considered what consequences should follow when police perform an illegal search and find evidence (which they leave in place) and then subsequently perform a legal search of the same premises and find the same evidence (which they seize). The Court held that the evidence is admissible if both the basis for the second search and the officers' decision to proceed with the second search existed before -- and independently of -- the performance of the initial, illegal search.

Even if an illegal search intervenes, in other words, evidence ultimately seized during a legal search can, in some cases, be attributed to the legal search, and accordingly admitted into evidence.

Determination of when the legal search and its results are truly "independent" of the initial illegality calls for a hypothetical inquiry into what would have happened if there had been no intervening illegality.

The Inevitable Discovery Doctrine

Inevitable discovery takes the hypothetical reasoning process of the independent source doctrine one step further.

In an inevitable discovery case, two things are always true. First, police have violated the Fourth Amendment. Second, as a direct consequence of the Fourth Amendment violation, police have discovered and seized evidence incriminating to the person whose Fourth Amendment rights were violated.

Under these circumstances, the exclusionary rule would ordinarily require the suppression of the incriminating evidence. Unlike in the case of independent source, the evidence here cannot be attributed to a legal search.

The inevitable discovery doctrine, however, can nevertheless save the evidence from suppression. It does so by adding a layer of hypothetical inquiry to the independent source scenario.

Inevitable discovery asks the judge to imagine that the police did not commit the Fourth Amendment violation -- the one that they did, in fact, commit, and that did directly lead to the seizure of the evidence. It then asks whether the evidence that was in reality obtained through the illegal search would have ultimately surfaced through legal police conduct that would have ultimately occurred if given the chance.

Under Nix v. Williams, if the answer to this question is yes, then the trial judge will admit the evidence as though it had actually been uncovered by that hypothetical, legal investigation that would eventually have occurred.

Why Emphasize Causation?

The theory behind the doctrinal emphasis on causation in both independent source and inevitable discovery doctrines is this: When police conduct a search without probable cause, then the evidence they uncover would have remained hidden were it not for the Fourth Amendment violation. It follows that restoring the way things would have been if the police had refrained from violating the Constitution -- that is, divesting the government of its ill-gotten gains -- means suppressing the evidence that was uncovered as a result of the wrongful search.

The government, on this theory, is not entitled to obtain evidence that would never have come to light in the absence of unconstitutional conduct. The exclusionary rule enforces this position by keeping the evidence out of the courtroom.

If, on the other hand, the unlawful search that took place was not necessary to the disclosure of the illegal evidence - if, that is, the evidence either was (independently), or would have eventually been, discovered and obtained through entirely legal means -- then the evidence no longer has that same character as essentially off-limits to the government.

Another way of putting this is to say that the point of suppressing evidence is to prevent illegal searches and seizures from putting the government in a better position than it would have occupied if it had followed the rules.

When the exclusion of evidence is understood in this light, inevitable discovery provides a way of asking whether the evidence obtained was really destined to come to light or whether it emerged only by virtue of police violating the law. Only in the latter case need the evidence be suppressed, because only then did the Fourth Amendment truly contemplate the ultimate loss of this evidence.

If, on the other hand, the evidence would have surfaced regardless of the illegal behavior, then exclusion is inappropriate, because it would prevent the jury from considering evidence that was destined to come to the government's attention.

Not All Cases Fit this "Evidentiary Destiny" Model: Warrantless Searches

There is, however, a set of Supreme Court precedents that does not fit this model of suppression. Decisions involving warrantless searches notably belong to this set.

When police carry out a warrantless search and seizure without an exigency (or other exception) to justify their failure to obtain a warrant, the resulting evidence is suppressed. The Fourth Amendment requires suppression notwithstanding the fact that the police misconduct did not involve the disclosure of evidence that was destined by the Fourth Amendment to remain hidden. Indeed, it is precisely the fact that a warrant would not have prevented the police from getting the evidence they needed that eliminates any possible justification for searching without a warrant.

Had the police conformed their behavior to the dictates of the Fourth Amendment, then, they still would have gotten the evidence. Yet, the law suppresses the evidence because they did not get a warrant.

The inevitable discovery doctrine could not sensibly apply to warrantless searches without obliterating the suppression of evidence in such cases. What makes warrantless searches improper is that police failed to take a required step -- intended to civilize the process -- prior to performing a search. The search itself and its disclosure of hidden evidence, however, is otherwise acceptable.

The suppression of the product of a warrantless search and seizure is accordingly not -- as it would be in the case of a search without probable cause -- an attempt to approximate what things would have looked like had police obeyed the law. It is, instead, a straightforward punishment for police who fail to take legally required steps that would have given them legal access to the desired evidence.

Knock-and-Announce and Evidentiary Destiny

The question in Hudson v. Michigan, then, is where a suppression remedy for knock-and-announce violations would fit into the framework above: Would it dislodge evidence destined to be left hidden, or would it constitute a punishment for failure to take a civilizing step?

When courts suppress evidence because police violate knock-and-announce, it is virtually always the case that the circumstances in play would satisfy the inevitable discovery exception -- if this exception applied.

Indeed, suppose that, in a given case, the inevitable discovery rule is not satisfied, for a warning and announcement of purpose would likely have led to the loss of evidence. In such a case, that very probability would justify a no-knock entry and thus remove the police conduct from the class of constitutional violations altogether. Police who can show that knocking and announcing would compromise the search about to take place (either evidentiarily or safety-wise) can accordingly dispense with the requirement.

Another way of saying this is to suggest that if the inevitable discovery exception to suppression applies to knock-and-announce, then the exception will preclude the suppression of any evidence obtained as a result of a no-knock entry. The failure to knock-and-announce will either be legal due to evanescent evidence (in which case the evidence should not be suppressed because there was no Fourth Amendment violation) or the failure to knock-and-announce will be illegal but will fall within the inevitable discovery doctrine and permit admission of the evidence on that ground.

Should Exclusion or Inevitable Discovery Govern No-Knock Cases?

So the knock-and-announce requirement is very much like the warrant requirement: If the Court wants there ever to be suppression of evidence, then the inevitable discovery doctrine cannot apply.

Exclusion will not approximate the way things would have been if police had complied with the Fourth Amendment, because compliance -- when legally required -- does not preclude the recovery of evidence. The purpose of knock-and-announce, like the purpose of the warrant requirement, is not to keep things hidden but rather, to force the police to take steps that civilize the investigative process.

Warrants ensure that an objective person makes a cool appraisal of police officers' basis for a search, and warrant affidavits provide a record for later review of that neutral appraisal. Knock-and-announce ensures that home searches are not quite as terrifying, humiliating and potentially lethal as they might otherwise be.

Putting the Government In A Worse Position

Many would say of both the warrant requirement and knock-and-announce, that the exclusionary rule is not appropriately applied at all. The Supreme Court has said, in Nix v. Williams, that suppression is not intended to place the government in a worse position than it would have occupied if it had complied with the Constitution. The suppression of evidence obtained after violations of either the warrant requirement or knock-and-announce does exactly that.

But the Supreme Court has applied the exclusionary rule to warrant violations and has strongly implied that the exclusionary rule will apply (and thus will not be subject to the inevitable discovery exception) in knock-and-announce cases as well.

In Wilson v. Arkansas, in which the Court officially recognized that the Fourth Amendment often requires knock-and-announce, a majority of the Court sent the particular case -- in which a convicted felon appealed his conviction - back to the lower courts. The remand was for a determination of whether a valid basis for foregoing knock-and-announce was present, as the government contended.

If there were no valid basis, one could accordingly conclude, the petitioner's conviction would be reversed. And that reversal, in turn, could only happen if a violation of knock-and-announce results in suppression, notwithstanding the fact that such suppression deprives the government of evidence that it would otherwise have (and thus puts the government in a worse position than it would have occupied in the absence of a constitutional violation).

If instead, evidence should be admitted regardless of whether police violate the Fourth Amendment when they fail to knock and announce, the Supreme Court's remand of Wilson would be inexplicable. The Court could simply have said "regardless of whether the police were right to forego knock-and-announce in this case, the conviction is affirmed, because no evidentiary consequences follow from violation of knock-and-announce." Its remanding thus strongly suggests that knock-and-announce will be enforced with the exclusionary rule and that inevitable discovery will therefore not apply.

Beyond predicting what the Court will do, moreover, it seems right to bar application of inevitable discovery to the knock-and-announce rule, just as it was right for the Court to bar its application to warrant violations.

Absent exclusion, police will have very little incentive to obtain a warrant. Appearing before a magistrate takes extra time that could be spent in the pursuit of other crimes. And a lawsuit in which the plaintiff proves that police lacked a warrant (but otherwise had probable cause) will ordinarily yield little in damages -- certainly not enough to motivate police to change their behavior or to tempt plaintiffs to bring such suits in the first place.

As in the case of warrants, without application of the exclusionary rule, police will have little incentive to comply with the knock-and-announce rule. Surprise -- in many cases -- will seem the best strategy for police in gaining control over premises in which evidence is present. Like the warrant process, knocking and announcing results in a relinquishment of some control over the investigative process, and police rarely relinquish control voluntarily.

Furthermore, a lawsuit in which a plaintiff shows that police searched properly but failed to say "Police, we have a warrant" before entering will not likely yield much in the way of damages. As with warrantless searches, then, the exclusionary rule -- even in its punitive form -- may be necessary to the effective deterrence of violations.

Justice Frank Murphy once said that "there is but one alternative to the rule of exclusion. That is no sanction at all." The knock-and-announce requirement is one that civilizes the search process and can prevent trauma and save lives. Exclusion accordingly seems vastly superior to no sanction at all.