Missouri v. McNeely,
569 U.S. ___ (2013)

Annotate this Case

NOTICE: This opinion is subject to formal revision before publication in the preliminary print of the United States Reports. Readers are requested to notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in order that corrections may be made before the preliminary print goes to press.



No. 11–1425



on writ of certiorari to the supreme court of missouri

[April 17, 2013]

     Justice Sotomayor announced the judgment of the Court and delivered the opinion of the Court with respect to Parts I, II–A, II–B, and IV, and an opinion with respect to Parts II–C and III, in which Justice Scalia, Justice Ginsburg, and Justice Kagan join.

     In Schmerber v. California, 384 U. S. 757 (1966) , this Court upheld a warrantless blood test of an individual arrested for driving under the influence of alcohol because the officer “might reasonably have believed that he was confronted with an emergency, in which the delay necessary to obtain a warrant, under the circumstances, threatened the destruction of evidence.” Id., at 770 (internal quotation marks omitted). The question presented here is whether the natural metabolization of alcohol in the bloodstream presents a per se exigency that justifies an exception to the Fourth Amendment’s warrant requirement for nonconsensual blood testing in all drunk-driving cases. We conclude that it does not, and we hold, consistent with general Fourth Amendment principles, that exigency in this context must be determined case by case based on the totality of the circumstances.


     While on highway patrol at approximately 2:08 a.m., a Missouri police officer stopped Tyler McNeely’s truck after observing it exceed the posted speed limit and repeatedly cross the centerline. The officer noticed several signs that McNeely was intoxicated, including McNeely’s bloodshot eyes, his slurred speech, and the smell of alcohol on his breath. McNeely acknowledged to the officer that he had consumed “a couple of beers” at a bar, App. 20, and he appeared unsteady on his feet when he exited the truck. After McNeely performed poorly on a battery of field-sobriety tests and declined to use a portable breath-test device to measure his blood alcohol concentration (BAC), the officer placed him under arrest.

     The officer began to transport McNeely to the station house. But when McNeely indicated that he would again refuse to provide a breath sample, the officer changed course and took McNeely to a nearby hospital for blood testing. The officer did not attempt to secure a warrant. Upon arrival at the hospital, the officer asked McNeely whether he would consent to a blood test. Reading from a standard implied consent form, the officer explained to McNeely that under state law refusal to submit voluntar- ily to the test would lead to the immediate revocation of his driver’s license for one year and could be used against him in a future prosecution. See Mo. Ann. Stat. §§577.020.1, 577.041 (West 2011). McNeely nonetheless refused. The officer then directed a hospital lab technician to take a blood sample, and the sample was secured at approximately 2:35 a.m. Subsequent laboratory testing measured McNeely’s BAC at 0.154 percent, which was well above the legal limit of 0.08 percent. See §577.012.1.

     McNeely was charged with driving while intoxicated (DWI), in violation of §577.010. [ 1 ] He moved to suppress the results of the blood test, arguing in relevant part that, under the circumstances, taking his blood for chemi- cal testing without first obtaining a search warrant vio- lated his rights under the Fourth Amendment. The trial court agreed. It concluded that the exigency exception to the warrant requirement did not apply because, apart from the fact that “[a]s in all cases involving intoxication, [McNeely’s] blood alcohol was being metabolized by his liver,” there were no circumstances suggesting the officer faced an emergency in which he could not practicably obtain a warrant. No. 10CG–CR01849–01 (Cir. Ct. Cape Giradeau Cty., Mo., Div. II, Mar. 3, 2011), App. to Pet. for Cert. 43a. On appeal, the Missouri Court of Appeals stated an intention to reverse but transferred the case directly to the Missouri Supreme Court. No. ED 96402 (June 21, 2011), id., at 24a.

     The Missouri Supreme Court affirmed. 358 S. W. 3d 65 (2012) (per curiam). Recognizing that this Court’s decision in Schmerber v. California, 384 U. S. 757 , “provide[d] the backdrop” to its analysis, the Missouri Supreme Court held that “Schmerber directs lower courts to engage in a totality of the circumstances analysis when determin- ing whether exigency permits a nonconsensual, warrantless blood draw.” 358 S. W. 3d, at 69, 74. The court further concluded that Schmerber “requires more than the mere dissipation of blood-alcohol evidence to support a warrantless blood draw in an alcohol-related case.” 358 S. W. 3d, at 70. According to the court, exigency depends heavily on the existence of additional “ ‘special facts,’ ” such as whether an officer was delayed by the need to investigate an ac- cident and transport an injured suspect to the hospital, as had been the case in Schmerber. 358 S. W. 3d, at 70, 74. Finding that this was “unquestionably a routine DWI case” in which no factors other than the natural dissi- pation of blood-alcohol suggested that there was an emergency, the court held that the nonconsensual warrantless blood draw violated McNeely’s Fourth Amendment right to be free from unreasonable searches of his person. Id., at 74–75.

     We granted certiorari to resolve a split of authority on the question whether the natural dissipation of alcohol in the bloodstream establishes a per se exigency that suffices on its own to justify an exception to the warrant requirement for nonconsensual blood testing in drunk-driving investigations. [ 2 ] See 567 U. S. ___ (2012). We now affirm.



     The Fourth Amendment provides in relevant part 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, and no Warrants shall issue, but upon probable cause.” Our cases have held that a warrantless search of the person is reasonable only if it falls within a recognized exception. See, e.g., United States v. Robinson, 414 U. S. 218, 224 (1973) . That principle applies to the type of search at issue in this case, which involved a compelled physical intrusion beneath McNeely’s skin and into his veins to obtain a sample of his blood for use as evidence in a criminal investigation. Such an invasion of bodily integrity implicates an individual’s “most personal and deep-rooted expectations of privacy.” Winston v. Lee, 470 U. S. 753, 760 (1985) ; see also Skinner v. Railway Labor Executives’ Assn., 489 U. S. 602, 616 (1989) .

     We first considered the Fourth Amendment restrictions on such searches in Schmerber, where, as in this case, a blood sample was drawn from a defendant suspected of driving while under the influence of alcohol. 384 U. S., at 758. Noting that “[s]earch warrants are ordinarily required for searches of dwellings,” we reasoned that “absent an emergency, no less could be required where intrusions into the human body are concerned,” even when the search was conducted following a lawful arrest. Id., at 770. We explained that the importance of requiring authorization by a “ ‘neutral and detached magistrate’ ” before allowing a law enforcement officer to “invade another’s body in search of evidence of guilt is indisputable and great.” Ibid. (quoting Johnson v. United States, 333 U. S. 10 –14 (1948)).

     As noted, the warrant requirement is subject to ex- ceptions. “One well-recognized exception,” and the one at issue in this case, “applies when the exigencies of the situation make the needs of law enforcement so compelling that a warrantless search is objectively reasonable under the Fourth Amendment.” Kentucky v. King, 563 U. S. ___, ___ (2011) (slip op., at 6) (internal quotation marks and brackets omitted). A variety of circumstances may give rise to an exigency sufficient to justify a warrantless search, including law enforcement’s need to provide emergency assistance to an occupant of a home, Michigan v. Fisher, 558 U. S. 45 –48 (2009) (per curiam), engage in “hot pursuit” of a fleeing suspect, United States v. San- tana, 427 U. S. 38 –43 (1976), or enter a burning building to put out a fire and investigate its cause, Michigan v. Tyler, 436 U. S. 499 –510 (1978). As is relevant here, we have also recognized that in some circumstances law enforcement officers may conduct a search without a warrant to prevent the imminent destruction of evidence. See Cupp v. Murphy, 412 U. S. 291, 296 (1973) ; Ker v. California, 374 U. S. 23 –41 (1963) (plurality opinion). While these contexts do not necessarily involve equiva- lent dangers, in each a warrantless search is potentially reasonable because “there is compelling need for official action and no time to secure a warrant.” Tyler, 436 U. S., at 509.

     To determine whether a law enforcement officer faced an emergency that justified acting without a warrant, this Court looks to the totality of circumstances. See Brigham City v. Stuart, 547 U. S. 398, 406 (2006) (finding officers’ entry into a home to provide emergency assistance “plainly reasonable under the circumstances”); Illinois v. Mc- Arthur, 531 U. S. 326, 331 (2001) (concluding that a warrantless seizure of a person to prevent him from returning to his trailer to destroy hidden contraband was reasonable “[i]n the circumstances of the case before us” due to exigency); Cupp, 412 U. S., at 296 (holding that a limited warrantless search of a suspect’s fingernails to preserve evidence that the suspect was trying to rub off was justified “[o]n the facts of this case”); see also Richards v. Wisconsin, 520 U. S. 385 –396 (1997) (rejecting a per se exception to the knock-and-announce requirement for felony drug investigations based on presumed exigency, and requiring instead evaluation of police conduct “in a particular case”). We apply this “finely tuned approach” to Fourth Amendment reasonableness in this context be- cause the police action at issue lacks “the traditional justification that . . . a warrant . . . provides.” Atwater v. Lago Vista, 532 U. S. 318, 347, n. 16 (2001) . Absent that established justification, “the fact-specific nature of the reasonableness inquiry,” Ohio v. Robinette, 519 U. S. 33, 39 (1996) , demands that we evaluate each case of alleged exigency based “on its own facts and circumstances.” Go-Bart Importing Co. v. United States, 282 U. S. 344, 357 (1931) . [ 3 ]

     Our decision in Schmerber applied this totality of the circumstances approach. In that case, the petitioner had suffered injuries in an automobile accident and was taken to the hospital. 384 U. S., at 758. While he was there receiving treatment, a police officer arrested the petitioner for driving while under the influence of alcohol and ordered a blood test over his objection. Id., at 758–759. After explaining that the warrant requirement applied generally to searches that intrude into the human body, we concluded that the warrantless blood test “in the present case” was nonetheless permissible because the officer “might reasonably have believed that he was confronted with an emergency, in which the delay necessary to obtain a warrant, under the circumstances, threatened ‘the destruction of evidence.’ ” Id., at 770 (quoting Preston v. United States, 376 U. S. 364, 367 (1964) ).

     In support of that conclusion, we observed that evidence could have been lost because “the percentage of alcohol in the blood begins to diminish shortly after drinking stops, as the body functions to eliminate it from the system.” 384 U. S., at 770. We added that “[p]articularly in a case such as this, where time had to be taken to bring the accused to a hospital and to investigate the scene of the accident, there was no time to seek out a magistrate and secure a warrant.” Id., at 770–771. “Given these special facts,” we found that it was appropriate for the police to act without a warrant. Id., at 771. We further held that the blood test at issue was a reasonable way to recover the evidence because it was highly effective, “involve[d] vir- tually no risk, trauma, or pain,” and was conducted in a reasonable fashion “by a physician in a hospital environment according to accepted medical practices.” Ibid. And in conclusion, we noted that our judgment that there had been no Fourth Amendment violation was strictly based “on the facts of the present record.” Id., at 772.

     Thus, our analysis in Schmerber fits comfortably within our case law applying the exigent circumstances exception. In finding the warrantless blood test reasonable in Schmerber, we considered all of the facts and circumstances of the particular case and carefully based our holding on those specific facts.


     The State properly recognizes that the reasonableness of a warrantless search under the exigency exception to the warrant requirement must be evaluated based on the totality of the circumstances. Brief for Petitioner 28–29. But the State nevertheless seeks a per se rule for blood testing in drunk-driving cases. The State contends that whenever an officer has probable cause to believe an individual has been driving under the influence of alcohol, exigent circumstances will necessarily exist because BAC evidence is inherently evanescent. As a result, the State claims that so long as the officer has probable cause and the blood test is conducted in a reasonable manner, it is categorically reasonable for law enforcement to obtain the blood sample without a warrant.

     It is true that as a result of the human body’s natural metabolic processes, the alcohol level in a person’s blood begins to dissipate once the alcohol is fully absorbed and continues to decline until the alcohol is eliminated. See Skinner, 489 U. S., at 623; Schmerber, 384 U. S., at 770–771. Testimony before the trial court in this case indicated that the percentage of alcohol in an individual’s blood typically decreases by approximately 0.015 percent to 0.02 percent per hour once the alcohol has been fully absorbed. App. 47. More precise calculations of the rate at which alcohol dissipates depend on various individual characteristics (such as weight, gender, and alcohol tolerance) and the circumstances in which the alcohol was consumed. See Stripp, Forensic and Clinical Issues in Alcohol Analysis, in Forensic Chemistry Handbook 437–441 (L. Kobilinsky ed. 2012). Regardless of the exact elimination rate, it is sufficient for our purposes to note that because an individual’s alcohol level gradually declines soon after he stops drinking, a significant delay in testing will negatively affect the probative value of the results. This fact was essential to our holding in Schmerber, as we recognized that, under the circumstances, further delay in order to secure a warrant after the time spent investigating the scene of the accident and transporting the injured suspect to the hospital to receive treatment would have threatened the destruction of evidence. 384 U. S., at 770–771.

     But it does not follow that we should depart from careful case-by-case assessment of exigency and adopt the categorical rule proposed by the State and its amici. In 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. See McDonald v. United States, 335 U. S. 451, 456 (1948) (“We cannot . . . excuse the absence of a search warrant without a showing by those who seek exemption from the constitutional mandate that the exigencies of the situation made [the search] imperative”). We do not doubt that some circumstances will make obtaining a warrant impractical such that the dissipation of alcohol from the bloodstream will support an exigency justifying a properly conducted warrantless blood test. That, however, is a reason to decide each case on its facts, as we did in Schmerber, not to accept the “considerable overgeneralization” that a per se rule would reflect. Richards, 520 U. S., at 393.

     The context of blood testing is different in critical respects from other destruction-of-evidence cases in which the police are truly confronted with a “ ‘now or never’ ” situation. Roaden v. Kentucky, 413 U. S. 496, 505 (1973) . In contrast to, for example, circumstances in which the suspect has control over easily disposable evidence, see Georgia v. Randolph, 547 U. S. 103 , n. 6 (2006); Cupp, 412 U. S., at 296, BAC evidence from a drunk-driving suspect naturally dissipates over time in a gradual and relatively predictable manner. Moreover, because a police officer must typically transport a drunk-driving suspect to a medical facility and obtain the assistance of someone with appropriate medical training before conducting a blood test, some delay between the time of the arrest or accident and the time of the test is inevitable regardless of whether police officers are required to obtain a warrant. See State v. Shriner, 751 N. W. 2d 538, 554 (Minn. 2008) (Meyer, J., dissenting). This reality undermines the force of the State’s contention, endorsed by the dissent, see post, at 3 (opinion of Thomas, J.), that we should recognize a categorical exception to the warrant requirement because BAC evidence “is actively being destroyed with every minute that passes.” Brief for Petitioner 27. Consider, for example, a situation in which the warrant process will not significantly increase the delay before the blood test is conducted because an officer can take steps to secure a warrant while the suspect is being transported to a medical facility by another officer. In such a circumstance, there would be no plausible justification for an exception to the warrant requirement.

     The State’s proposed per se rule also fails to account for advances in the 47 years since Schmerber was decided that allow for the more expeditious processing of warrant applications, particularly in contexts like drunk-driving investigations where the evidence offered to establish probable cause is simple. The Federal Rules of Criminal Procedure were amended in 1977 to permit federal magistrate judges to issue a warrant based on sworn testimony communicated by telephone. See 91Stat. 319. As amended, the law now allows a federal magistrate judge to con- sider “information communicated by telephone or other reliable electronic means.” Fed. Rule Crim. Proc. 4.1. States have also innovated. Well over a majority of States allow police officers or prosecutors to apply for search warrants remotely through various means, including telephonic or radio communication, electronic communication such as e-mail, and video conferencing. [ 4 ] And in addition to technology-based developments, jurisdictions have found other ways to streamline the warrant process, such as by using standard-form warrant applications for drunk-driving investigations. [ 5 ]

     We by no means claim that telecommunications inno- vations have, will, or should eliminate all delay from the warrant-application process. Warrants inevitably take some time for police officers or prosecutors to complete and for magistrate judges to review. Telephonic and electronic warrants may still require officers to follow time-consuming formalities designed to create an adequate record, such as preparing a duplicate warrant before calling the magistrate judge. See Fed. Rule Crim. Proc. 4.1(b)(3). And improvements in communications technology do not guarantee that a magistrate judge will be available when an officer needs a warrant after making a late-night arrest. But technological developments that enable police officers to secure warrants more quickly, and do so without undermining the neutral magistrate judge’s essential role as a check on police discretion, are relevant to an assessment of exigency. That is particularly so in this context, where BAC evidence is lost gradually and relatively predictably. [ 6 ]

     Of course, there are important countervailing concerns. While experts can work backwards from the BAC at the time the sample was taken to determine the BAC at the time of the alleged offense, longer intervals may raise questions about the accuracy of the calculation. For that reason, exigent circumstances justifying a warrantless blood sample may arise in the regular course of law enforcement due to delays from the warrant application process. But adopting the State’s per se approach would improperly ignore the current and future technological developments in warrant procedures, and might well diminish the incentive for jurisdictions “to pursue progressive approaches to warrant acquisition that preserve the protections afforded by the warrant while meeting the legitimate interests of law enforcement.” State v. Rodriguez, 2007 UT 15, ¶46, 156 P. 3d 771, 779.

     In short, while the natural dissipation of alcohol in the blood may support a finding of exigency in a specific case, as it did in Schmerber, it does not do so categorically. Whether a warrantless blood test of a drunk-driving suspect is reasonable must be determined case by case based on the totality of the circumstances.


     In an opinion concurring in part and dissenting in part, The Chief Justice agrees that the State’s proposed per se rule is overbroad because “[f]or exigent circumstances to justify a warrantless search . . . there must . . . be ‘no time to secure a warrant.’ ” Post, at 6 (quoting Tyler, 436 U. S., at 509). But The Chief Justice then goes on to suggest his own categorical rule under which a warrantless blood draw is permissible if the officer could not secure a warrant (or reasonably believed he could not secure a warrant) in the time it takes to transport the suspect to a hospital or similar facility and obtain medical assistance. Post, at 8–9. Although we agree that delay inherent to the blood-testing process is relevant to evaluating exigency, see supra, at 10, we decline to substitute The Chief Justice’s modified per se rule for our traditional totality of the circumstances analysis.

     For one thing, making exigency completely dependent on the window of time between an arrest and a blood test produces odd consequences. Under The Chief Justice’s rule, if a police officer serendipitously stops a suspect near an emergency room, the officer may conduct a noncon- sensual warrantless blood draw even if all agree that a warrant could be obtained with very little delay under the circumstances (perhaps with far less delay than an average ride to the hospital in the jurisdiction). The rule would also distort law enforcement incentives. As with the State’s per se rule, The Chief Justice’s rule might discourage efforts to expedite the warrant process because it categorically authorizes warrantless blood draws so long as it takes more time to secure a warrant than to obtain medical assistance. On the flip side, making the requirement of independent judicial oversight turn exclusively on the amount of time that elapses between an arrest and BAC testing could induce police departments and individual officers to minimize testing delay to the detriment of other values. The Chief Justice correctly observes that “[t]his case involves medical personnel drawing blood at a medical facility, not police officers doing so by the side of the road.” Post, at 6–7, n. 2. But The Chief Justice does not say that roadside blood draws are necessarily un- reasonable, and if we accepted The Chief Justice’s approach, they would become a more attractive option for the police.


     The remaining arguments advanced in support of a per se exigency rule are unpersuasive.

     The State and several of its amici, including the United States, express concern that a case-by-case approach to exigency will not provide adequate guidance to law enforcement officers deciding whether to conduct a blood test of a drunk-driving suspect without a warrant. The Chief Justice and the dissent also raise this concern. See post, at 1, 9–10 (opinion of Roberts, C. J.); post, at 5–7 (opinion of Thomas, J.). While the desire for a bright-line rule is understandable, the Fourth Amendment will not tolerate adoption of an overly broad categorical approach that would dilute the warrant requirement in a context where significant privacy interests are at stake. Moreover, a case-by-case approach is hardly unique within our Fourth Amendment jurisprudence. Numerous police actions are judged based on fact-intensive, totality of the circumstances analyses rather than according to categorical rules, including in situations that are more likely to require police officers to make difficult split-second judgments. See, e.g., Illinois v. Wardlow, 528 U. S. 119 –125 (2000) (whether an officer has reasonable suspicion to make an investigative stop and to pat down a suspect for weapons under Terry v. Ohio, 392 U. S. 1 (1968) ); Robinette, 519 U. S., at 39–40 (whether valid consent has been given to search); Tennessee v. Garner, 471 U. S. 1 –9, 20 (1985) (whether force used to effectuate a seizure, including deadly force, is reasonable). As in those contexts, we see no valid substitute for careful case-by-case evaluation of reasonableness here. [ 7 ]

     Next, the State and the United States contend that the privacy interest implicated by blood draws of drunk-driving suspects is relatively minimal. That is so, they claim, both because motorists have a diminished expectation of privacy and because our cases have repeatedly indicated that blood testing is commonplace in society and typically involves “virtually no risk, trauma, or pain.” Schmerber, 384 U. S., at 771. See also post, at 3, and n. 1 (opinion of Thomas, J.).

     But the fact that people are “accorded less privacy in . . . automobiles because of th[e] compelling governmental need for regulation,” California v. Carney, 471 U. S. 386, 392 (1985) , does not diminish a motorist’s privacy interest in preventing an agent of the government from piercing his skin. As to the nature of a blood test conducted in a medical setting by trained personnel, it is concededly less intrusive than other bodily invasions we have found unreasonable. See Winston, 470 U. S., at 759–766 (surgery to remove a bullet); Rochin v. California, 342 U. S. 165 –174 (1952) (induced vomiting to extract narcotics capsules ingested by a suspect violated the Due Process Clause). For that reason, we have held that medically drawn blood tests are reasonable in appropriate circumstances. See Skinner, 489 U. S., at 618–633 (upholding warrantless blood testing of railroad employees involved in certain train accidents under the “special needs” doctrine); Schmerber, 384 U. S., at 770–772. We have never retreated, however, from our recognition that any compelled intrusion into the human body implicates significant, constitutionally protected privacy interests.

     Finally, the State and its amici point to the compelling governmental interest in combating drunk driving and contend that prompt BAC testing, including through blood testing, is vital to pursuit of that interest. They argue that is particularly so because, in addition to laws that make it illegal to operate a motor vehicle under the influence of alcohol, all 50 States and the District of Columbia have enacted laws that make it per se unlawful to operate a motor vehicle with a BAC of over 0.08 percent. See National Highway Traffic Safety Admin. (NHTSA), Al- cohol and Highway Safety: A Review of the State of Knowledge 167 (No. 811374, Mar. 2011) (NHTSA Review). [ 8 ] To enforce these provisions, they reasonably assert, accurate BAC evidence is critical. See also post, at 4–5 (opinion of Roberts, C. J.); post, at 4–5 (opinion of Thomas, J.).

     “No one can seriously dispute the magnitude of the drunken driving problem or the States’ interest in eradicating it.” Michigan Dept. of State Police v. Sitz, 496 U. S. 444, 451 (1990) . Certainly we do not. While some progress has been made, drunk driving continues to exact a terrible toll on our society. See NHTSA, Traffic Safety Facts, 2011 Data 1 (No. 811700, Dec. 2012) (reporting that 9,878 people were killed in alcohol-impaired driving crashes in 2011, an average of one fatality every 53 minutes).

     But the general importance of the government’s interest in this area does not justify departing from the warrant requirement without showing exigent circumstances that make securing a warrant impractical in a particular case. To the extent that the State and its amici contend that applying the traditional Fourth Amendment totality-of-the-circumstances analysis to determine whether an exigency justified a warrantless search will undermine the governmental interest in preventing and prosecuting drunk-driving offenses, we are not convinced.

     As an initial matter, States have a broad range of legal tools to enforce their drunk-driving laws and to secure BAC evidence without undertaking warrantless nonconsensual blood draws. For example, all 50 States have adopted implied consent laws that require motorists, as a condition of operating a motor vehicle within the State, to consent to BAC testing if they are arrested or otherwise detained on suspicion of a drunk-driving offense. See NHTSA Review 173; supra, at 2 (describing Missouri’s implied consent law). Such laws impose significant consequences when a motorist withdraws consent; typically the motorist’s driver’s license is immediately suspended or revoked, and most States allow the motorist’s refusal to take a BAC test to be used as evidence against him in a subsequent criminal prosecution. See NHTSA Review 173–175; see also South Dakota v. Neville, 459 U. S. 553 –564 (1983) (holding that the use of such an adverse inference does not violate the Fifth Amendment right against self-incrimination).

     It is also notable that a majority of States either place significant restrictions on when police officers may obtain a blood sample despite a suspect’s refusal (often limiting testing to cases involving an accident resulting in death or serious bodily injury) or prohibit nonconsensual blood tests altogether. [ 9 ] Among these States, several lift restrictions on nonconsensual blood testing if law enforcement officers first obtain a search warrant or similar court order. [ 10 ] Cf. Bullcoming v. New Mexico, 564 U. S. ___, ___ (2011) (slip op., at 3) (noting that the blood test was obtained pursuant to a warrant after the petitioner refused a breath test). We are aware of no evidence indicating that restrictions on nonconsensual blood testing have compromised drunk-driving enforcement efforts in the States that have them. And in fact, field studies in States that permit nonconsensual blood testing pursuant to a warrant have suggested that, although warrants do impose administrative burdens, their use can reduce breath-test-refusal rates and improve law enforcement’s ability to recover BAC evidence. See NHTSA, Use of Warrants for Breath Test Refusal: Case Studies 36–38 (No. 810852, Oct. 2007).

     To be sure, “States [may] choos[e] to protect privacy beyond the level that the Fourth Amendment requires.” Virginia v. Moore, 553 U. S. 164, 171 (2008) . But wide-spread state restrictions on nonconsensual blood testing provide further support for our recognition that compelled blood draws implicate a significant privacy interest. They also strongly suggest that our ruling today will not “severely hamper effective law enforcement.” Garner, 471 U. S., at 19.


     The State argued before this Court that the fact that alcohol is naturally metabolized by the human body creates an exigent circumstance in every case. The State did not argue that there were exigent circumstances in this particular case because a warrant could not have been obtained within a reasonable amount of time. In his testimony before the trial court, the arresting officer did not identify any other factors that would suggest he faced an emergency or unusual delay in securing a warrant. App. 40. He testified that he made no effort to obtain a search warrant before conducting the blood draw even though he was “sure” a prosecuting attorney was on call and even though he had no reason to believe that a magistrate judge would have been unavailable. Id., at 39, 41–42. The officer also acknowledged that he had obtained search warrants before taking blood samples in the past without difficulty. Id., at 42. He explained that he elected to forgo a warrant application in this case only because he believed it was not legally necessary to obtain a warrant. Id., at 39–40. Based on this testimony, the trial court concluded that there was no exigency and specifically found that, although the arrest took place in the middle of the night, “a prosecutor was readily available to apply for a search warrant and a judge was readily available to issue a warrant.” App. to Pet. for Cert. 43a. [ 11 ]

     The Missouri Supreme Court in turn affirmed that judgment, holding first that the dissipation of alcohol did not establish a per se exigency, and second that the State could not otherwise satisfy its burden of establishing exigent circumstances. 358 S. W. 3d, at 70, 74–75. In petitioning for certiorari to this Court, the State challenged only the first holding; it did not separately contend that the warrantless blood test was reasonable regardless of whether the natural dissipation of alcohol in a suspect’s blood categorically justifies dispensing with the warrant requirement. See Pet. for Cert. i.

     Here and in its own courts the State based its case on an insistence that a driver who declines to submit to testing after being arrested for driving under the influence of alcohol is always subject to a nonconsensual blood test without any precondition for a warrant. That is incorrect.

     Although the Missouri Supreme Court referred to this case as “unquestionably a routine DWI case,” 358 S. W. 3d, at 74, the fact that a particular drunk-driving stop is “routine” in the sense that it does not involve “ ‘special facts,’ ” ibid., such as the need for the police to attend to a car accident, does not mean a warrant is required. Other factors present in an ordinary traffic stop, such as the procedures in place for obtaining a warrant or the avail- ability of a magistrate judge, may affect whether the police can obtain a warrant in an expeditious way and therefore may establish an exigency that permits a warrantless search. The relevant factors in determining whether a warrantless search is reasonable, including the practical problems of obtaining a warrant within a timeframe that still preserves the opportunity to obtain reliable evidence, will no doubt vary depending upon the circumstances in the case.

     Because this case was argued on the broad proposition that drunk-driving cases present a per se exigency, the arguments and the record do not provide the Court with an adequate analytic framework for a detailed discussion of all the relevant factors that can be taken into account in determining the reasonableness of acting without a warrant. It suffices to say that the metabolization of alcohol in the bloodstream and the ensuing loss of evidence are among the factors that must be considered in deciding whether a warrant is required. No doubt, given the large number of arrests for this offense in different jurisdictions nationwide, cases will arise when anticipated delays in obtaining a warrant will justify a blood test without judicial authorization, for in every case the law must be concerned that evidence is being destroyed. But that inquiry ought not to be pursued here where the question is not properly before this Court. Having rejected the sole argument presented to us challenging the Missouri Supreme Court’s decision, we affirm its judgment.

*  *  *

     We hold that in drunk-driving investigations, the natural dissipation of alcohol in the bloodstream does not con- stitute an exigency in every case sufficient to justify conducting a blood test without a warrant.

     The judgment of the Missouri Supreme Court is affirmed.

It is so ordered.


1  As a result of his two prior drunk-driving convictions, McNeely was charged with a class D felony under Missouri law, which carries a maximum imprisonment term of four years. See Mo. Ann. Stat. §§558.011, 577.023.1(5), 577.023.3 (West 2011).
2  Compare 358 S. W. 3d 65 (2012) (case below), State v. Johnson, 744 N. W. 2d 340 (Iowa 2008) (same conclusion), and State v. Rodriguez, 2007 UT 15, 156 P. 3d 771 (same), with State v. Shriner, 751 N. W. 2d 538 (Minn. 2008) (holding that the natural dissipation of blood-alcohol evidence alone constitutes a per se exigency), State v. Bohling, 173 Wis. 2d 529, 494 N. W. 2d 399 (1993) (same); State v. Woolery, 116 Idaho 368, 775 P. 2d 1210 (1989) (same).
3  We have recognized a limited class of traditional exceptions to the warrant requirement that apply categorically and thus do not require an assessment of whether the policy justifications underlying the ex-ception, which may include exigency-based considerations, are im-plicated in a particular case. See, e.g., California v. Acevedo, 500U. S. 565, 569–570 (1991) (automobile exception); United States v. Robinson, –235 (1973) (searches of a person incident to a lawful arrest). By contrast, the general exigency exception, which asks whether an emergency existed that justified a warrantless search, naturally calls for a case-specific inquiry.
4  See Ala. Rule Crim. Proc. 3.8(b) (2012–2013); Alaska Stat. §12.35.015 (2012); Ariz. Rev. Stat. Ann. §§13–3914(C), 13–3915(D), (E) (West 2010); Ark. Code Ann. §16–82–201 (2005); Cal. Penal Code Ann. §1526(b) (West 2011); Colo. Rule Crim. Proc. 41(c)(3) (2012); Ga. Code Ann. §17–5–21.1 (2008); Haw. Rules Penal Proc. 41(h)–(i) (2013); Idaho Code §§19–4404, 19–4406 (Lexis 2004); Ind. Code §35–33–5–8 (2012); Iowa Code §§321J.10(3), 462A.14D(3) (2009) (limited to specific circumstances involving accidents); Kan. Stat. Ann. §§22–2502(a), 22–2504 (2011 Cum. Supp.); La. Code Crim. Proc. Ann., Arts. 162.1(B), (D) (West 2003); Mich. Comp. Laws Ann. §§780.651(2)–(6) (West 2006); Minn. Rules Crim. Proc. 33.05, 36.01–36.08 (2010 and Supp. 2013); Mont. Code Ann. §§46–5–221, 46–5–222 (2012); Neb. Rev. Stat. §§29–814.01, 29–814.03, 29–814.05 (2008); Nev. Rev. Stat. §§179.045(2), (4) (2011); N. H. Rev. Stat. Ann. §595–A:4–a (Lexis Supp. 2012); N. J. Rule Crim. Proc. 3:5–3(b) (2013); N. M. Rules Crim. Proc. 5–211(F)(3), (G)(3) (Supp. 2012); N. Y. Crim. Proc. Law Ann. §§690.35(1), 690.36(1), 690.40(3), 690.45(1), (2) (West 2009); N. C. Gen. Stat. Ann. §15A–245(a)(3) (Lexis 2011); N. D. Rules Crim. Proc. 41(c)(2)–(3) (2012–2013); Ohio Rules Crim. Proc. 41(C)(1)–(2) (2011); Okla. Stat. Ann., Tit. 22, §§1223.1, 1225(B) (West 2011); Ore. Rev. Stat. §§133.545(5)–(6) (2011); Pa. Rules Crim. Proc. 203(A), (C) (2012); S. D. Codified Laws §§23A–35–4.2, 23A–35–5, 23A–35–6 (2004); Utah Rule Crim. Proc. 40(l) (2012); Vt. Rules Crim. Proc. 41(c)(4), (g)(2) (Supp. 2012); Va. Code Ann. §19.2–54 (Lexis Supp. 2012); Wash. Super. Ct. Crim. Rule 2.3(c) (2002); Wis. Stat. §968.12(3) (2007–2008); Wyo. Stat. Ann. §31–6–102(d) (2011); see generally 2 W. LaFave, Search and Seizure §4.3(b), pp. 511–516, andn. 29 (4th ed. 2004) (describing oral search warrants and collecting state laws). Missouri requires that search warrants be in writing and does not permit oral testimony, thus excluding telephonic warrants. Mo. Ann. Stat. §§542.276.2(1), 542.276.3 (West Supp. 2012). State law does permit the submission of warrant applications “by facsimile or other electronic means.” §542.276.3.
5  During the suppression hearing in this case, McNeely entered into evidence a search-warrant form used in drunk-driving cases by the prosecutor’s office in Cape Girardeau County, where the arrest took place. App. 61–69. The arresting officer acknowledged that he had used such forms in the past and that they were “readily available.” Id., at 41–42.
6  The dissent claims that a “50-state survey [is] irrelevant to the actual disposition of this case” because Missouri requires written warrant applications. Post, at 8. But the per se exigency rule that the State seeks and the dissent embraces would apply nationally because it treats “the body’s natural metabolization of alcohol” as a sufficient basis for a warrantless search everywhere and always. Post, at 1. The technological innovations in warrant procedures that many Stateshave adopted are accordingly relevant to show that the per se rule is overbroad.
7  The dissent contends that officers in the field will be unable to apply the traditional totality of the circumstances test in this context because they will not know all of the relevant facts at the time of an arrest. See post, at 6. But because “[t]he police are presumably familiar with the mechanics and time involved in the warrant process in their particular jurisdiction,” post, at 8 (opinion of Roberts, C. J.), we expect that officers can make reasonable judgments about whether the warrant process would produce unacceptable delay under the circumstances. Reviewing courts in turn should assess those judgments “ ‘from the perspective of a reasonable officer on the scene, rather than with the 20/20 vision of hindsight.’ ” Ryburn v. Huff, 565 U. S. ___, ___ (2012) (per curiam) (slip op., at 8).
8  Pursuant to congressional directive, the NHTSA conditions federal highway grants on States’ adoption of laws making it a per se offense to operate a motor vehicle with a BAC of 0.08 percent or greater. See ; 23 CFR §1225.1 (2012). Several federal prohibitions on drunk driving also rely on the 0.08 percent standard. E.g., 32 CFR §§234.17(c)(1)(ii), 1903.4(b)(1)(i)–(ii); 36 CFR §4.23(a)(2). In addition, 32 States and the District of Columbia have adopted laws that impose heightened penalties for operating a motor vehicle at or above a BAC of 0.15 percent. See NHTSA Review 175.
9  See Ala. Code §32–5–192(c) (2010); Alaska Stat. §§28.35.032(a), 28.35.035(a) (2012); Ariz. Rev. Stat. Ann. §28–1321(D)(1) (West 2012); Ark. Code Ann. §§5–65–205(a)(1), 5–65–208(a)(1) (Supp. 2011);Conn. Gen. Stat. §§14–227b(b), 14–227c(b) (2011); Fla. Stat. Ann. §316.1933(1)(a) (West 2006); Ga. Code Ann. §§40–5–67.1(d), (d.1) (2011); Haw. Rev. Stat. §291E–15 (2009 Cum. Supp.), §§291E–21(a), 291E–33 (2007), §291E–65 (2009 Cum. Supp.); Iowa Code §§321J.9(1), 321J.10(1), 321J.10A(1) (2009); Kan. Stat. Ann. §§8–1001(b), (d) (2001); Ky. Rev. Stat. Ann. §189A.105(2) (Lexis Supp. 2012); La. Rev. Stat. Ann. §§32:666.A(1)(a)(i), (2) (Supp. 2013); Md. Transp. Code Ann. §§16–205.1(b)(i)(1), (c)(1) (Lexis 2012); Mass. Gen. Laws Ann., ch. 90, §§24(1)(e), (f)(1) (West 2012); Mich. Comp. Laws Ann. §257.625d(1) (West 2006); Miss. Code Ann. §63–11–21 (1973–2004); Mont. Code Ann. §§61–8–402(4), (5) (2011); Neb. Rev. Stat. §60–498.01(2) (2012Cum. Supp.), §60–6,210 (2010); N. H. Rev. Stat. Ann. §§265–A:14(I),265–A:16 (West 2012 Cum. Supp.); N. M. Stat. Ann. §66–8–111(A) (LexisNexis 2009); N. Y. Veh. & Traf. Law Ann. §§1194(2)(b)(1), 1194(3) (West 2011); N. D. Cent. Code Ann. §39–20–01.1(1) (Lexis Supp. 2011), §39–20–04(1) (Lexis 2008); Okla. Stat., Tit. 47, §753 (West Supp. 2013); Ore. Rev. Stat. §813.100(2) (2011); 75 Pa. Cons. Stat. §1547(b)(1) (2004); R. I. Gen. Laws §§31–27–2.1(b), 31–27–2.9(a) (Lexis 2010); S. C. Code Ann. §56–5–2950(B) (Supp. 2011); Tenn. Code Ann. §§55–10–406(a)(4), (f) (2012); Tex. Transp. Code Ann. §§724.012(b), 724.013 (West 2011); Vt. Stat. Ann., Tit. 23, §§1202(b), (f) (2007); Wash. Rev. Code §§46.20.308 (2)–(3), (5) (2012); W. Va. Code Ann. §17C–5–7 (Lexis Supp. 2012); Wyo. Stat. Ann. §31–6–102(d) (Lexis 2011).
10  See Ariz. Rev. Stat. Ann. §28–1321(D)(1) (West 2012); Ga. Code Ann. §§40–5–67.1(d), (d.1) (2011); Ky. Rev. Stat. Ann. §189A.105(2)(b) (Lexis Supp. 2012); Mich. Comp. Laws Ann. §257.625d(1) (West 2006); Mont. Code Ann. §61–8–402(5) (2011); N. M. Stat. Ann. §66–8–111(A) (LexisNexis 2009); N. Y. Veh. & Traf. Law Ann. §§1194(2)(b)(1), 1194(3) (West 2011); Ore. Rev. Stat. 813.320(2)(b) (2011); R. I. Gen. Laws §31–27–2.9(a) (Lexis 2010); Tenn. Code Ann. §55–10–406(a)(4) (2012); Vt. Stat. Ann., Tit. 23, §1202(f) (2007); Wash. Rev. Code §46.20.308(1) (2012); W. Va. Code Ann. §17C–5–7 (Supp. 2012) (as interpreted in State v. Stone, 229 W. Va. 271, ___, 728 S. E. 2d 155, 167–168 (2012)); Wyo. Stat. Ann. §31–6–102(d) (2011); see also State v. Harris, 763 N. W. 2d 269, 273–274 (Iowa 2009) (per curiam) (recognizing that Iowa law imposes a warrant requirement subject to a limited case-specific exigency exception).
11  No findings were made by the trial court concerning how long a warrant would likely have taken to issue under the circumstances. The minimal evidence presented on this point was not uniform. A second patrol officer testified that in a typical DWI case, it takes between 90 minutes and 2 hours to obtain a search warrant following an arrest. App. 53–54. McNeely, however, also introduced an exhibit documenting six recent search warrant applications for blood testing in Cape Girardeau County that had shorter processing times. Id., at 70.
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