No Knock-and-Announce? No Problem: The Supreme Court Holds Evidence from No-Knock Entries Admissible In Court

Earlier this month, in Hudson v. Michigan, the U.S. Supreme Court handed down a ruling that reveals an alarming insensitivity to civil liberties.

The Court announced that when police enter a dwelling in violation of the "knock and announce" requirement, the evidence they find is available for use in a criminal prosecution.

The case is significant because it evidences the Justices' growing antipathy toward the exclusionary rule, a rule that exists to motivate the police to comply with the demands of the Constitution.

The Knock and Announce Requirement

The Fourth Amendment guarantees the right of the people to be free from unreasonable searches and seizures. As the Court has understood this right since at least 1967, it provides, among other things, that police may not violate people's reasonable expectations of privacy without justification. Justification, in turn, must ordinarily take the form of probable cause to believe that a search would turn up evidence of crime. When the intended search is of a home, the police must obtain a warrant issued in advance by a neutral magistrate, certifying that they have made the required showing of probable cause.

In addition to imposing these requirements, the Court has indicated that police must conduct searches and seizures in a reasonable manner. Even when police have a warrant certifying probable cause, in other words, they still have to execute the warrant in a legitimate fashion. The Court has identified one component of reasonable execution as police knocking and announcing their presence and purpose and then waiting an appropriate period of time for an answer, before forcing their way in to perform an authorized search.

It was only eleven years ago, in Wilson v. Arkansas, that the Court explicitly recognized that the Fourth Amendment requires the police to "knock and announce." But the requirement itself is not new. Courts have long assumed that this obligation - part of the English common law - represents an element of the freedom from unreasonable searches and seizures.

The Supreme Court has provided several reasons for knock-and-announce. First, it helps reduce the fear and distress that people inside a private home predictably experience when police open or break down the door of their dwelling without notice. Second, and relatedly, if police break into a home without any warning, residents might reasonably believe that burglars have entered and accordingly use deadly force against a potentially violent intruder. And third, the destruction of property entailed in an unannounced entry may well be unnecessary: A simple knock and announcement could yield cooperation and thereby minimize the damage occasioned by the officers' intrusion.

As the Court recognized in Wilson, of course, there are occasions on which police have to be able to make an unannounced entry. Such an entry is justified, the Court explained, "under circumstances presenting a threat of physical violence" or "where police officers have reason to believe that evidence would likely be destroyed if advance notice were given." As with virtually every constitutional requirement, then, knock-and-announce admits of some exceptions.

The Court emphasized in Richards v. Wisconsin, however, that police may not forego knock-and-announce in whole categories of crimes based on the overall likelihood of encountering exigencies that might justify a no-knock entry in such cases. The Court accordingly refused to create an exception to knock-and-announce for all felony drug cases.

The Fourth Amendment Exclusionary Rule

The case that the Court decided a few weeks ago did not, in theory, alter any of the law discussed above. Contrary to some reports, the Court did not say in Hudson v. Michigan that the Fourth Amendment no longer requires police to adhere to the knock-and-announce requirement. What the Court did say is that when police violate the rule (and consequently, the Fourth Amendment) by failing to knock, to identify themselves, or to wait a reasonable period of time before entering a dwelling, the prosecution may nonetheless freely introduce any evidence they discover at a later criminal prosecution.

Understanding this ruling requires some background in the Fourth Amendment Exclusionary Rule. Beginning in 1914 for the federal government and 1961 for the states, violation of the Fourth Amendment has resulted in the suppression of evidence recovered because of the violation. Though the Court has advanced more than one explanation for suppressing such evidence, the one that has survived into the present is the deterrence rationale: If prosecutors may offer illegally obtained evidence in court against the victim of an unreasonable search or seizure, then police will lack any incentive to refrain from violating the Fourth Amendment. Suppressing the evidence, on this reasoning, provides a necessary deterrent.

Since its initial embrace of the Fourth Amendment Exclusionary Rule, the Court has limited its scope in a variety of contexts. For example, evidence seized in violation of the Fourth Amendment is suppressed at the victim's criminal trial, but not at proceedings before the grand jury or at a civil trial. Illegally-obtained evidence is suppressed when the prosecutor is engaged in affirmatively proving guilt, but not when she is impeaching the credibility of a criminal defendant witness who has contradicted evidence seized in violation of the Fourth Amendment.

And even in the prosecutor's main presentation at trial, a judge will admit illegally obtained evidence if the prosecution persuades her that an independent - and legal - alternative investigative process either did or would have yielded the very same evidence, or that the link between the constitutional violation and the evidentiary discovery was somehow attenuated by time or intervening events.

These limitations and others reflect the Court's continuing struggle to balance two competing interests: first, the interest in teaching the police that (like crime itself, as the cliché holds) violating people's privacy rights does not pay; and, second, the interest in effectively prosecuting criminals for their offenses.

Tension between these two interests is, to some degree, unavoidable: If suppressing evidence did not hamper successful prosecution of crime, then suppression would yield no deterrent benefits. It is the cost of exclusion, in other words, that deters police from violating the Fourth Amendment.

In response to this tension, the Court has adopted a balancing approach that asks the following question: Is the marginal deterrent effect of suppressing evidence in a particular category of cases sufficient to justify the release of guilty criminals who would otherwise have gone to prison?

As numerous critics have pointed out, the cost in question typically encompasses the total loss of convictions due to the exclusionary rule, rather than just the marginal cost of suppressing evidence in the limited category of cases that the Court is examining. The Court thus measures the total cost of having an exclusionary rule against the limited benefit of applying it to a particular category of cases. Because this is the balance, it is rare for the Justices - when confronting a potential exception - to find exclusion justified.

Knock-and-Announce and the Exclusionary Rule: Justice Scalia's Arguments

In Hudson v. Michigan, a majority decided that violations of knock-and-announce do not trigger exclusion. Accordingly, knock-and-announce violations join the growing list of exceptions to the application of the exclusionary rule.

In his opinion for the Court, Justice Scalia catalogues a number of reasons for the knock-and-announce exception to exclusion. He says - as every such exception decision says - that the immense cost of the exclusionary rule outweighs the marginal benefit to be gained from suppressing evidence found after a knock-and-announce violation. He cites many other decisions announcing exceptions, thus purportedly demonstrating that this decision breaks no new ground.

Justice Scalia also claims that it is not accurate to say that the discovery of evidence "results from" the violation of knock-and-announce, because it is the legal search rather than the premature entry that leads the police to the evidence. Finally, he contends that police already have an incentive to knock and announce, to avoid being sued and to avoid being shot as intruders.

One could (and the dissent does) mobilize effective responses to each of the majority's arguments, but underlying the sheer quantity of claims lurks a covert hostility to the procedural requirements of the Fourth Amendment. I will focus on Justice Scalia's "causation" argument, because it is very telling in this regard.

The Court's cost/benefit analysis is difficult to engage. It is here, as elsewhere, stacked against exclusion, for the reasons I describe above. Furthermore, even if the two sides of the balance were correctly calibrated, it would be hard to determine how valuable it is to deter violations of the Fourth Amendment, as compared to how valuable it is to convict all guilty people of the crimes they commit. As Justice Scalia says in a very different context, "it is … like judging whether a particular line is longer than a particular rock is heavy."

Justice Scalia does not, however, simply make the familiar arguments in a new situation. He takes an entire category of Fourth Amendment violation - the failure to adhere to knock-and-announce requirements - and says that exclusion will never result from such a violation.

The exemption does not apply simply to particular proceedings or to violations of knock-and-announce committed in good faith. Rather, even if an officer has no reason at all to knock down a door and terrify the inhabitants of a private home, he can do so -- as long as he has a warrant -- without risking an acquittal in the criminal trial to follow. That is, the violation - no matter how egregious and damaging -- will not affect the criminal trial in any way.

Justice Scalia's Causation Argument - And Why It Proves Too Much

Perhaps recognizing how different this is from prior exceptions, Justice Scalia makes an additional argument about causation. The argument, noted above, is that the failure to knock and announce does not "cause" discovery of evidence; the entry itself (based on a valid warrant) does.

The problem with this argument is that it proves too much. When police, for example, enter a home on the basis of probable cause but without a warrant - that is, when they violate the warrant requirement of the Fourth Amendment - the Court traditionally suppresses the fruit of the illegal entry. And it does so despite the fact that if police had obtained a warrant, they would likely have found the very evidence that they actually did find. Put differently, it was the police officers' successful accumulation of probable cause - and not their failure to get a warrant - that caused them to discover the evidence.

Thus, violating the warrant requirement alone, like violating knock-and-announce alone, will typically yield the same evidence that compliance would have yielded. That is how a procedural requirement works: Unlike a search in the absence of probable cause, disregard of purely procedural limits does not typically uncover evidence that would otherwise have remained hidden.

On occasion, however, getting a warrant or knocking and announcing will affect the outcome of a search. The time delay, in both cases, could provide an opportunity for defendants to hide or destroy evidence that police would otherwise have found. But crucially, when this risk is evident in a particular case, the exigency - under existing law - justifies a warrantless or a no-knock entry, respectively. The cases in which police must get a warrant and knock and announce, then, are precisely those cases in which getting the warrant and making an announcement will probably have no impact on the success of the search.

Importantly, though, this does not mean that getting a warrant and knocking and announcing generally make no difference. The more substantive requirements like probable cause - when police adhere to them - protect most innocent people from having to be searched at all. Purely procedural requirements like the warrant and knock-and-announce, by contrast, do not necessarily limit the universe of people subject to searches and seizures. Instead, they affect the process by which the police interact with that universe of people.

When police obtain a warrant, a detached and neutral magistrate hears the basis for the officers' suspicion in advance, and that hearing forces officers to articulate what it was that made them believe a search of John Doe would be appropriate. For that reason too, a warrant helps reassure a frightened resident that someone other than the police at the door has authorized an entry that might otherwise have seemed uncomfortably similar to a criminal act.

Knock-and-announce serves this purpose as well. An unarmed civilian sitting at home with his family is less likely to become traumatized for life if he knows in advance that an armed person or group is about to enter the premises, and that - importantly - the person or group is there under the authority of the law.

Justice Scalia takes the perspective of the police as he examines the knock-and-announce requirement and the suppression that will no longer follow from its violation. From that perspective, the ultimate result - getting the evidence - is the same, regardless of how the entry is accomplished. From the perspective of the person enjoying the privacy and security of his home, however, there is all the difference in the world between the "shock and awe" of an unannounced entry and the potentially civilized cooperation involved when there is an opportunity to put on a bathrobe and comfort the children before admitting the police.

With suppression of evidence no longer available in any case of a knock-and-announce violation, we must now rely on police officers to understand that distinction, when a majority of learned Supreme Court Justices have failed to do so.