The U.S. Supreme Court Rules That Blood Tests for Drunk Driving Suspects Require a Search Warrant: A Wise Decision?

The U.S. Supreme Court recently decided the case of Missouri v. McNeely.  In McNeely, a majority of the Court rejected the idea of a “per se” exigent circumstances exception to the warrant requirement for blood tests in drunk-driving cases.  That is, the Court held that police may not automatically order a blood test on someone whom they have lawfully arrested for DWI (driving while intoxicated) but must instead seek a warrant, absent a reason to skip the warrant—a reason that goes beyond the simple fact that blood-alcohol-concentration diminishes with the passage of time.

The Court held that police must conduct a “totality of the circumstances” exigency analysis to determine whether seeking a warrant prior to performing a blood test would “significantly undermin[e] the efficacy of the search” in an individual case.  In this column, I will consider whether the Court’s ruling makes sense, in light of what generally happens in DWI cases. I will also discuss an alternative approach proposed by the Chief Justice.

Why Get a Warrant?

To determine whether the Court was right to apply the warrant requirement to BAC (blood-alcohol concentration) testing, it may be helpful first to consider the source and purpose of the warrant requirement.  The Fourth Amendment’s text provides that “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated . . . .”  The text does not itself require a warrant, but it does go on to say that warrants may issue only in the presence of probable cause, among other things.  Notwithstanding the lack of a textual warrant requirement anywhere in the Constitution (and the similar lack of a textual requirement for probable cause as a prerequisite to a search), the U.S. Supreme Court has interpreted the phrase “unreasonable searches” to require—in the garden-variety case—that police have probable cause, and that they obtain a warrant prior to performing a search.

The rationale for requiring a warrant is that it permits a neutral and detached person, one who is not engaged in the “often competitive enterprise of ferreting out crime,” as the Court has put it, to take a sober second look at the evidence that has aroused a police officer’s suspicion.  The magistrate who reviews the warrant application can then determine, without possessing the zeal of someone who spends most of her time tracking down criminals, whether there really is probable cause, as the officer believes there is.  Though the word “seizures” appears in the same phrase in the Fourth Amendment as the word “searches,” the Court has been more generous in permitting police to skip the warrant in the case of seizures than it has in the case of searches.

The Typical Drunk-Driving Arrest Scenario, and the Facts in McNeely

This background all becomes relevant to the Court’s ruling when we turn to the drunk-driving arrest scenario.  Typically, such an arrest occurs when police observe a pattern of driving that suggests intoxication, including weaving or other demonstrated incompetence at the wheel.  Based on their observations of such driving, which amount to “reasonable suspicion” of DWI, police may pull over or temporarily “stop” the drunk-driving suspect for further investigation.

At this stage, police may ask the suspect questions, look into the suspect’s eyes (for tell-tale signs of intoxication), sniff at the air near the suspect (for the stink of alcohol), and perhaps ask the suspect to walk a straight line or otherwise display the sort of coordination that most sober people exhibit.  The officer may also ask the suspect to take a breathalyzer test.  If the suspect’s behavior, appearance, fragrance, and/or breathalyzer results (or the refusal to take a breathalyzer test) give rise to probable cause to believe that the driver is intoxicated, then the officer may arrest him for DWI.  An arrest is a “seizure” for Fourth Amendment purposes, but under a case called United States v. Watson, it does not require a warrant when it occurs in public.  Police were therefore able to arrest Tyler G. McNeely for DWI, based on probable cause, without first seeking a magistrate’s neutral review.

Once they arrested Mr. McNeely, police brought him to a nearby hospital and asked a lab technician to take a blood sample for a BAC test, over McNeely’s protests.  The test results showed McNeely to be at .154 percent, well over the legal limit, and he was subsequently charged with DWI.  In the trial court, McNeely moved to suppress the BAC test results, arguing that police performed an unreasonable search on him by testing his blood without a search warrant and without his consent.  The trial court agreed and suppressed the evidence, and the State Supreme Court affirmed the trial court’s decision.

The Exigent Circumstances Exception

Though the Court ordinarily requires police to obtain a warrant before performing a search, it recognizes exceptions to the warrant requirement for a variety of situations that can confront the police.  One important exception exists for “exigent circumstances,” which are emergency situations that demand immediate action.  When police, for example, are in “hot pursuit” of a fleeing felon who runs into a house, they face an “exigent circumstance” that excuses the ordinary requirement that they obtain a warrant before entering a private home.

One of the exigencies that the Court has recognized as pertinent to whether police may proceed with a search in the absence of a warrant is the risk that evidence could be destroyed in the time it takes to procure a search warrant.  Because of this risk, if police have probable cause to believe that a suspect who is located inside his home (and who knows that police are right outside the door) is in possession of drugs, police may be able to enter immediately, without a warrant.  That is because waiting for a magistrate’s approval would give the suspect the opportunity (and motive) to destroy the evidence in his possession.  The State of Missouri, in McNeely, argued that whenever police have a drunk-driving suspect in custody, they face an exigent circumstance of this sort: With every passing minute of blood-test delay, the suspect’s blood-alcohol-concentration—the best evidence of DWI—diminishes.

The Supreme Court rejected the State’s argument for an across-the-board exigency exception for blood tests in drunk driving cases, ruling that while the passage of time does reduce the BAC of the suspect, it does not necessarily and always present an emergency.  Given that police can obtain warrants electronically and otherwise, in a relatively rapid manner, the Court noted, getting a warrant is often a practical option, even in a DWI situation.  Since a warrant is usually required in the absence of an exigency in a particular case, the Court held in McNeely that the same approach should apply to drunk-driving arrests:  if police can show a particular exigent circumstance (beyond the always-present ongoing metabolization of alcohol by a suspect), judged by the “totality of the circumstances,” then they may test his blood without a warrant.  Otherwise, a warrant will be required.

The Problem With the Majority’s Approach

There is a part of me that finds the majority’s approach understandable and even reassuring.  In a time in which the Court seems to be regularly announcing inroads on existing constitutional protections, the McNeely decision holds the line and says that we will not have an across-the-board exception to the warrant requirement for a particular class of criminal evidence:  BAC of drunk drivers.  Rather, to rely on “exigent circumstances,” police must demonstrate a genuine emergency that they confront in the individual case, regardless of whether such cases “in general” create an exigency.  As a result of this decision, moreover, it seems that people who could otherwise be wrongfully subjected to unjustified blood tests might be spared, because a magistrate can reject the officers’ potentially overzealous perceived need to collect evidence.

The reason, however, that I am ultimately unconvinced by the majority’s analysis turns on the nature of DWI evidence.  As mentioned earlier, the best evidence of DWI is the result of a blood-alcohol test taken as close to the time of driving as possible.  As everyone acknowledges, a person’s blood-alcohol-concentration steadily diminishes over time as soon as the person stops drinking.  Therefore, in every case in which a suspect is actually guilty of DWI, evidence of guilt is literally vanishing with whatever time it might take for an officer to seek and obtain a search warrant.

The vanishing of evidence may not matter, in some cases, because the suspect’s BAC is so high that it will continue to exceed the legal limit even after whatever delay is occasioned by seeking a warrant.  But a police officer arresting a suspect for DWI is not in a very good position to assess whether that is true in a particular case.  And unlike the usual exigency context in which a suspect, alerted to the arrival of police, might destroy evidence of drug possession (because he has the opportunity and motive to do so before a warrant issues), the drunk driver has no choice but to destroy evidence, because his liver detoxifies his blood automatically, without any voluntary input from him.

Justice Thomas’s Dissent

Furthermore, as Justice Thomas notes in his dissent, even if the suspect remains drunk enough for a conviction at the time of the warrant-authorized BAC test, most states have heightened penalties for the driver whose blood alcohol level is .15% or above, which is nearly double the legal limit of .08%.  A short delay in a blood test could therefore mean the difference between proving a BAC of over .08% and proving one of over .15%, a high BAC that would permit more serious punishment.  There is, of course, no way for a police officer arresting a DWI suspect to know whether or not the suspect’s current BAC is on the verge of dropping below .15%.

Justice Thomas offers a useful and witty hypothetical example to illustrate the exigency that police face in DWI cases.  Imagine that police see an individual worker carrying bundles out of a warehouse and throwing each bundle into a large bonfire.  Assume that the police have probable cause to believe that the bundles contain marijuana but that there is only one worker, so police expect it to take hours for all of the bundles to be destroyed.  Justice Thomas observes that police would be able to search the warehouse without a warrant, based on the exigency posed by the imminent destruction of evidence.

In Justice Thomas’s scenario, it would be absurd to suggest that police must seek a warrant because the delay involved in seeking a warrant might still leave some of the bundles intact, since the worker burning the bundles is operating by himself.  For similar reasons, Justice Thomas contends, the fact that some level of alcohol might remain in the suspect’s blood even after a warrant-seeking delay, does not alter the fact that the suspect’s diminishing blood-alcohol-concentration creates an exigency justifying an immediate blood test.  Officers need not countenance the destruction of evidence just because there might still be other undestroyed evidence left behind.

Chief Justice Roberts’s Elegant Compromise

Chief Justice Roberts, in an opinion (concurring in part and dissenting in part), joined by Justices Breyer and Alito, arrives at what I think is a smart and effective solution to the DWI-exigency problem.  The Chief Justice points out that ordinarily, an exigent circumstance offers the police an immediate opportunity for a search.  For example, a police officer with probable cause for a search might be standing at a suspect’s front door, knowing that the suspect is aware of the officer’s presence and that the suspect has motive and opportunity to destroy the drugs in his possession.  Only by entering the house immediately can the officers prevent the destruction of evidence.

In the case of a drunk driver, by contrast, officers typically cannot perform an immediate search, even though the BAC level is diminishing.  Instead, police ordinarily must call upon medical personnel, present at a hospital, to draw the blood (rather than drawing it themselves at the scene).

This distinction between ordinary searches and blood tests is relevant in McNeely, because seeking a warrant, in the latter case, does not necessarily delay the blood test.  In some cases, a ride with the suspect to the nearest hospital will take the same amount of time (or more time) than the simultaneous acquisition of a warrant (by telephone or through other available electronic means).  In such cases, police can obtain a warrant and also order blood collection as soon as someone qualified is available to draw the blood.  And when they can do so, the Chief Justice says, they should do so.  After all, review by a detached and neutral magistrate is presumptively required by the Fourth Amendment case law.

Chief Justice Roberts is realistic about the uncertainties in a DWI arrest situation.  Police may believe that getting a warrant will take longer than a trip to the hospital for a blood draw.  If their belief is reasonable, says the Chief Justice, then they do not need to seek a warrant at all.  Furthermore, if they do make an attempt to get a warrant, but the magistrate has not yet reviewed the warrant application by the time a medical technician is available to draw blood, the officers can go ahead and order the BAC test, rather than waiting for the magistrate’s decision and thereby delaying the test:  “If an officer could reasonably conclude that there is not sufficient time to seek and receive a warrant, or he applies for one but does not receive a response before blood can be drawn, a warrantless blood draw may ensue.”

The Chief Justice’s solution would work well, because it properly recognizes that any delay in the blood test will result in the loss of evidence.  At the same time, his opinion accommodates the majority’s concern, and it acknowledges that seeking a warrant in these circumstances does not always occasion a delay in the search.  In addition to addressing the problem effectively, this approach also gives police guidance about what to do when they arrest a drunk driver.  By contrast, the majority’s approach offers officers virtually no guidance at all, but states only that “[i]n those drunk-driving investigations where police officers can reasonably obtain a warrant before a blood sample can be drawn without significantly undermining the efficacy of the search, the Fourth Amendment mandates that they do so” (emphasis added).  Such a vague directive, perhaps ironically, may significantly undermine the efficacy of the majority’s opinion.