(Slip Opinion)              OCTOBER TERM, 2012                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

                        MISSOURI v. MCNEELY

       CERTIORARI TO THE SUPREME COURT OF MISSOURI

    No. 11–1425. Argued January 9, 2013—Decided April 17, 2013
Respondent McNeely was stopped by a Missouri police officer for speed-
  ing and crossing the centerline. After declining to take a breath test
  to measure his blood alcohol concentration (BAC), he was arrested
  and taken to a nearby hospital for blood testing. The officer never at-
  tempted to secure a search warrant. McNeely refused to consent to
  the blood test, but the officer directed a lab technician to take a sam-
  ple. McNeely’s BAC tested well above the legal limit, and he was
  charged with driving while intoxicated (DWI). He moved to suppress
  the blood test result, arguing that taking his blood without a warrant
  violated his Fourth Amendment rights. The trial court agreed, con-
  cluding that the exigency exception to the warrant requirement did
  not apply because, apart from the fact that McNeely’s blood alcohol
  was dissipating, no circumstances suggested that the officer faced an
  emergency.      The State Supreme Court affirmed, relying on
  Schmerber v. California, 384 U. S. 757, in which this Court upheld a
  DWI suspect’s warrantless blood test where the officer “might rea-
  sonably have believed that he was confronted with an emergency, in
  which the delay necessary to obtain a warrant, under the circum-
  stances, threatened ‘the destruction of evidence,’ ” id., at 770. This
  case, the state court found, involved a routine DWI investigation
  where no factors other than the natural dissipation of blood alcohol
  suggested that there was an emergency, and, thus, the nonconsensu-
  al warrantless test violated McNeely’s right to be free from unrea-
  sonable searches of his person.
Held: The judgment is affirmed.
358 S. W. 3d 65, affirmed.
     JUSTICE SOTOMAYOR delivered the opinion of the Court with respect
  to Parts I, II–A, II–B, and IV, concluding that in drunk-driving inves-
  tigations, the natural dissipation of alcohol in the bloodstream does
2                        MISSOURI v. MCNEELY

                                  Syllabus

    not constitute an exigency in every case sufficient to justify conduct-
    ing a blood test without a warrant. Pp. 4–13, 20–23.
       (a) The principle that a warrantless search of the person is reason-
    able only if it falls within a recognized exception, see, e.g., United
    States v. Robinson, 414 U. S. 218, 224, applies here, where the search
    involved a compelled physical intrusion beneath McNeely’s skin and
    into his veins to obtain a blood sample to use as evidence in a crimi-
    nal investigation. One recognized exception “applies when ‘ “the exi-
    gencies of the situation” make the needs of law enforcement so com-
    pelling that [a] warrantless search is objectively reasonable.’ ”
    Kentucky v. King, 563 U. S. ___, ___. This Court looks to the totality
    of circumstances in determining whether an exigency exits. See
    Brigham City v. Stuart, 547 U. S. 398, 406. Applying this approach
    in Schmerber, the Court found a warrantless blood test reasonable af-
    ter considering all of the facts and circumstances of that case and
    carefully basing its holding on those specific facts, including that al-
    cohol levels decline after drinking stops and that testing was delayed
    while officers transported the injured suspect to the hospital and in-
    vestigated the accident scene. Pp. 4–8.
       (b) The State nonetheless seeks a per se rule, contending that exi-
    gent circumstances necessarily exist when an officer has probable
    cause to believe a person has been driving under the influence of al-
    cohol because BAC evidence is inherently evanescent. Though a per-
    son’s blood alcohol level declines until the alcohol is eliminated, it
    does not follow that the Court should depart from careful case-by-
    case assessment of exigency. When officers in drunk-driving investi-
    gations can reasonably obtain a warrant before having a blood sam-
    ple 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. Circumstances may
    make obtaining a warrant impractical such that the alcohol’s dissipa-
    tion will support an exigency, but that is a reason to decide each case
    on its facts, as in Schmerber, not to accept the “considerable overgen-
    eralization” that a per se rule would reflect, Richards v. Wisconsin,
    520 U. S. 385, 393. Blood testing is different in critical respects from
    other destruction-of-evidence cases. Unlike a situation where, e.g., a
    suspect has control over easily disposable evidence, see Cupp v. Mur-
    phy, 412 U. S. 291, 296, BAC evidence naturally dissipates in a grad-
    ual and relatively predictable manner. Moreover, because an officer
    must typically take a DWI suspect to a medical facility and obtain a
    trained medical professional’s assistance before having a blood test
    conducted, some delay between the time of the arrest or accident and
    time of the test is inevitable regardless of whether a warrant is ob-
    tained. The State’s rule also fails to account for advances in the 47
                     Cite as: 569 U. S. ____ (2013)                      3

                                Syllabus

  years since Schmerber was decided that allow for the more expedi-
  tious processing of warrant applications, particularly in contexts like
  drunk-driving investigations where the evidence supporting probable
  cause is simple. The natural dissipation of alcohol in the blood may
  support an exigency finding in a specific case, as it did in Schmerber,
  but it does not do so categorically. Pp. 8–13.
     (c) Because the State sought a per se rule here, it did not argue that
  there were exigent circumstances in this particular case. The argu-
  ments and the record thus do not provide the Court with an adequate
  framework for a detailed discussion of all the relevant factors that
  can be taken into account in determining the reasonableness of act-
  ing 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. Pp. 20–23.
     JUSTICE SOTOMAYOR, joined by JUSTICE SCALIA, JUSTICE GINSBURG,
  and JUSTICE KAGAN, concluded in Part III that other arguments ad-
  vanced by the State and amici in support of a per se rule are unper-
  suasive. Their concern that a case-by-case approach to exigency will
  not provide adequate guidance to law enforcement officers may make
  the desire for a bright-line rule understandable, but the Fourth
  Amendment will not tolerate adoption of an overly broad categorical
  approach in this context. A fact-intensive, totality of the circum-
  stances, approach is hardly unique within this Court’s Fourth
  Amendment jurisprudence. See, e.g., Illinois v. Wardlow, 528 U. S.
  119, 123–125. They also contend that the privacy interest implicated
  here is minimal. But motorists’ diminished expectation of privacy
  does not diminish their privacy interest in preventing a government
  agent from piercing their skin. And though a blood test conducted in
  a medical setting by trained personnel is less intrusive than other
  bodily invasions, this Court has never retreated from its recognition
  that any compelled intrusion into the human body implicates signifi-
  cant, constitutionally protected privacy interests. Finally, the gov-
  ernment’s general interest in combating drunk driving does not justi-
  fy departing from the warrant requirement without showing exigent
  circumstances that make securing a warrant impractical in a particu-
  lar case. Pp. 15–20.

  SOTOMAYOR, J., announced the judgment of the Court and delivered
the opinion of the Court with respect to Parts I, II–A, II–B, and IV, in
which SCALIA, KENNEDY, GINSBURG, and KAGAN, JJ., joined, and an
opinion with respect to Parts II–C and III, in which SCALIA, GINSBURG,
and KAGAN, JJ., joined. KENNEDY, J., filed an opinion concurring in
part. ROBERTS, C. J., filed an opinion concurring in part and dissenting
4                    MISSOURI v. MCNEELY

                             Syllabus

in part, in which BREYER and ALITO, JJ., joined. THOMAS, J., filed a
dissenting opinion.
                       Cite as: 569 U. S. ____ (2013)                              1

                            Opinion of the Court

    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, Wash­
    ington, D. C. 20543, of any typographical or other formal errors, in order
    that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                  _________________

                                  No. 11–1425
                                  _________________


   MISSOURI, PETITIONER v. TYLER G. MCNEELY
    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 neces­
sary to obtain a warrant, under the circumstances, threat­
ened 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 require­
ment for nonconsensual blood testing in all drunk-driving
cases. We conclude that it does not, and we hold, con­
sistent with general Fourth Amendment principles, that
exigency in this context must be determined case by case
based on the totality of the circumstances.
2                          MISSOURI v. MCNEELY

                             Opinion of the Court

                               I
   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 blood­
shot 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 approxi­
mately 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
——————
    1 As   a result of his two prior drunk-driving convictions, McNeely was
                   Cite as: 569 U. S. ____ (2013)               3

                       Opinion of the Court

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 warrant­
less 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,
—————— 

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).

                                               

4                      MISSOURI v. MCNEELY

                          Opinion of the Court

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 emer­
gency, 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 require­
ment for nonconsensual blood testing in drunk-driving
investigations.2 See 567 U. S. ___ (2012). We now affirm.
                             II

                               

                             A

   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 prin­
ciple 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
——————
  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).
                 Cite as: 569 U. S. ____ (2013)            5

                     Opinion of the Court

“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 re­
quired 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. (quot­
ing Johnson v. United States, 333 U. S. 10, 13–14 (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 emer­
gency assistance to an occupant of a home, Michigan v.
Fisher, 558 U. S. 45, 47–48 (2009) (per curiam), engage in
“hot pursuit” of a fleeing suspect, United States v. San­
tana, 427 U. S. 38, 42–43 (1976), or enter a burning building
to put out a fire and investigate its cause, Michigan v.
Tyler, 436 U. S. 499, 509–510 (1978). As is relevant here,
we have also recognized that in some circumstances law
enforcement officers may conduct a search without a
6                  MISSOURI v. MCNEELY

                      Opinion of the Court

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, 40–41 (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 “plain­
ly reasonable under the circumstances”); Illinois v. Mc-
Arthur, 531 U. S. 326, 331 (2001) (concluding that a war­
rantless 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 exi­
gency); 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 justi­
fied “[o]n the facts of this case”); see also Richards v.
Wisconsin, 520 U. S. 385, 391–396 (1997) (rejecting a
per se exception to the knock-and-announce requirement
for felony drug investigations based on presumed exigen­
cy, 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
                    Cite as: 569 U. S. ____ (2013)                   7

                         Opinion of the Court

(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 or­
dered 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 pre­
sent 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 de­
struction 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
——————
  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, 500
U. S. 565, 569–570 (1991) (automobile exception); United States v.
Robinson, 414 U. S. 218, 224–235 (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.
8                  MISSOURI v. MCNEELY

                     Opinion of the Court

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 environ­
ment 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 excep­
tion. 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.
                             B
  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–
                 Cite as: 569 U. S. ____ (2013)            9

                     Opinion of the Court

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 character­
istics (such as weight, gender, and alcohol tolerance) and
the circumstances in which the alcohol was consumed.
See Stripp, Forensic and Clinical Issues in Alcohol Analy­
sis, in Forensic Chemistry Handbook 437–441 (L. Kobilin­
sky ed. 2012). Regardless of the exact elimination rate, it
is sufficient for our purposes to note that because an indi­
vidual’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 cate­
gorical 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
10                 MISSOURI v. MCNEELY

                     Opinion of the Court

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 overgeneraliza­
tion” that a per se rule would reflect. Richards, 520 U. S.,
at 393.
   The context of blood testing is different in critical re­
spects 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, 116, 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 con­
ducting 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 under­
mines 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 Peti­
tioner 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 justifica­
tion for an exception to the warrant requirement.
   The State’s proposed per se rule also fails to account for
                     Cite as: 569 U. S. ____ (2013)                   11

                          Opinion of the Court

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 magis­
trate judges to issue a warrant based on sworn testimony
communicated by telephone. See 91 Stat. 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 communica­
tion such as e-mail, and video conferencing.4 And in addi­
——————
  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 circum­
stances 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
12                     MISSOURI v. MCNEELY

                         Opinion of the Court

tion 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 technolo­
gy do not guarantee that a magistrate judge will be avail­
able 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 es­
sential 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

—————— 

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, and
     

n. 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.
                     Cite as: 569 U. S. ____ (2013)                   13

                         Opinion of the Court
                       Opinion of SOTOMAYOR, J.

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 en­
forcement 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 progres­
sive approaches to warrant acquisition that preserve the
protections afforded by the warrant while meeting the
legitimate interests of law enforcement.” State v. Rodri-
guez, 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 sus­
pect is reasonable must be determined case by case based
on the totality of the circumstances.
                            C
  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
——————
  6 The dissent claims that a “50-state survey [is] irrelevant to the ac­

tual 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 States
have adopted are accordingly relevant to show that the per se rule is
overbroad.
14                  MISSOURI v. MCNEELY

                      Opinion of the Court
                    Opinion of SOTOMAYOR, J.

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 war­
rant (or reasonably believed he could not secure a war­
rant) 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 aver­
age 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 require­
ment of independent judicial oversight turn exclusively on
the amount of time that elapses between an arrest and
BAC testing could induce police departments and individ­
ual 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
                  Cite as: 569 U. S. ____ (2013)           15

                      Opinion of the Court
                    Opinion of SOTOMAYOR, J.

not say that roadside blood draws are necessarily un-
reasonable, and if we accepted THE CHIEF JUSTICE’s ap­
proach, they would become a more attractive option for the
police.
                              III
   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 en­
forcement 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 circum­
stances 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, 123–125
(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)); Robi-
nette, 519 U. S., at 39–40 (whether valid consent has been
given to search); Tennessee v. Garner, 471 U. S. 1, 8–9, 20
(1985) (whether force used to effectuate a seizure, includ­
ing deadly force, is reasonable). As in those contexts, we
see no valid substitute for careful case-by-case evaluation
16                      MISSOURI v. MCNEELY

                          Opinion of the Court
                        Opinion of SOTOMAYOR, J.

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 expecta­
tion 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 un­
reasonable. See Winston, 470 U. S., at 759–766 (surgery
to remove a bullet); Rochin v. California, 342 U. S. 165,
172–174 (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 circum­
stances. See Skinner, 489 U. S., at 618–633 (upholding
——————
  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 partic­
ular 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).
                     Cite as: 569 U. S. ____ (2013)                    17

                         Opinion of the Court
                       Opinion of SOTOMAYOR, J.

warrantless blood testing of railroad employees involved
in certain train accidents under the “special needs” doc­
trine); Schmerber, 384 U. S., at 770–772. We have never
retreated, however, from our recognition that any com­
pelled intrusion into the human body implicates signifi­
cant, 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 influ­
ence 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 Re­
view).8 To enforce these provisions, they reasonably as­
sert, 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 eradi­
cating it.” Michigan Dept. of State Police v. Sitz, 496 U. S.
444, 451 (1990). Certainly we do not. While some pro­
gress has been made, drunk driving continues to exact a

——————
  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
U. S. C. §163(a); 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.
18                 MISSOURI v. MCNEELY

                     Opinion of the Court
                   Opinion of SOTOMAYOR, J.

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 exi­
gency 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 noncon­
sensual 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 conse­
quences 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,
554, 563–564 (1983) (holding that the use of such an ad­
verse 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
                     Cite as: 569 U. S. ____ (2013)                  19

                         Opinion of the Court
                       Opinion of SOTOMAYOR, J.

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 re­
strictions on nonconsensual blood testing if law enforce­
ment officers first obtain a search warrant or similar court
order.10 Cf. Bullcoming v. New Mexico, 564 U. S. ___, ___
——————
  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) (2012
Cum. 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)
20                    MISSOURI v. MCNEELY

                         Opinion of the Court

(2011) (slip op., at 3) (noting that the blood test was ob­
tained 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 compro­
mised 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 administra­
tive 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 “se­
verely hamper effective law enforcement.” Garner, 471
U. S., at 19.
                            IV
  The State argued before this Court that the fact that
alcohol is naturally metabolized by the human body cre­
ates 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
—————— 

(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).
                     Cite as: 569 U. S. ____ (2013)                  21

                         Opinion of the Court

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 magis­
trate 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 chal­
lenged 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
——————
  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 document­
ing six recent search warrant applications for blood testing in Cape
Girardeau County that had shorter processing times. Id., at 70.
22                  MISSOURI v. MCNEELY

                      Opinion of the Court

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 test­
ing 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 war­
rant. 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 judi­
                 Cite as: 569 U. S. ____ (2013)           23

                     Opinion of the Court

cial authorization, for in every case the law must be con­
cerned 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 ar­
gument presented to us challenging the Missouri Supreme
Court’s decision, we affirm its judgment.
                        *     *     *
  We hold that in drunk-driving investigations, the natu­
ral 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.
                  Cite as: 569 U. S. ____ (2013)            1

                 KENNEDY, J., concurring in part

SUPREME COURT OF THE UNITED STATES
                          _________________

                          No. 11–1425
                          _________________


   MISSOURI, PETITIONER v. TYLER G. MCNEELY
    ON WRIT OF CERTIORARI TO THE SUPREME COURT OF 

                      MISSOURI

                         [April 17, 2013] 


   JUSTICE KENNEDY, concurring in part.
   I join Parts I, II–A, II–B, and IV of the opinion for the
Court.
   For the reasons stated below this case does not call for
the Court to consider in detail the issue discussed in Part
II–C and the separate opinion by THE CHIEF JUSTICE.
   As to Part III, much that is noted with respect to the
statistical and survey data will be of relevance when this
issue is explored in later cases. The repeated insistence in
Part III that every case be determined by its own circum-
stances is correct, of course, as a general proposition; yet
it ought not to be interpreted to indicate this question is
not susceptible of rules and guidelines that can give im-
portant, practical instruction to arresting officers, in-
struction that in any number of instances would allow a
warrantless blood test in order to preserve the critical
evidence.
   States and other governmental entities which enforce
the driving laws can adopt rules, procedures, and protocols
that meet the reasonableness requirements of the Fourth
Amendment and give helpful guidance to law enforcement
officials. And this Court, in due course, may find it appro-
priate and necessary to consider a case permitting it to
provide more guidance than it undertakes to give today.
   As the opinion of the Court is correct to note, the instant
case, by reason of the way in which it was presented and
2                  MISSOURI v. MCNEELY

                KENNEDY, J., concurring in part

decided in the state courts, does not provide a framework
where it is prudent to hold any more than that always
dispensing with a warrant for a blood test when a driver is
arrested for being under the influence of alcohol is incon-
sistent with the Fourth Amendment.
                 Cite as: 569 U. S. ____ (2013)           1

                   Opinion of ROBERTS, C. J.

SUPREME COURT OF THE UNITED STATES
                         _________________

                         No. 11–1425
                         _________________


   MISSOURI, PETITIONER v. TYLER G. MCNEELY
    ON WRIT OF CERTIORARI TO THE SUPREME COURT OF 

                      MISSOURI


                        [April 17, 2013] 


   CHIEF JUSTICE ROBERTS, with whom JUSTICE BREYER
and JUSTICE ALITO join, concurring in part and dissenting
in part.
   A police officer reading this Court’s opinion would have
no idea—no idea—what the Fourth Amendment requires
of him, once he decides to obtain a blood sample from a
drunk driving suspect who has refused a breathalyzer
test. I have no quarrel with the Court’s “totality of the
circumstances” approach as a general matter; that is what
our cases require. But the circumstances in drunk driving
cases are often typical, and the Court should be able to
offer guidance on how police should handle cases like the
one before us.
   In my view, the proper rule is straightforward. Our
cases establish that there is an exigent circumstances
exception to the warrant requirement. That exception
applies when there is a compelling need to prevent the
imminent destruction of important evidence, and there is
no time to obtain a warrant. The natural dissipation of
alcohol in the bloodstream constitutes not only the immi-
nent but ongoing destruction of critical evidence. That
would qualify as an exigent circumstance, except that
there may be time to secure a warrant before blood can be
drawn. If there is, an officer must seek a warrant. If an
officer could reasonably conclude that there is not, the
exigent circumstances exception applies by its terms, and
2                  MISSOURI v. MCNEELY

                    Opinion of ROBERTS, C. J.

the blood may be drawn without a warrant.
                           I
    The Fourth Amendment provides:
     “The 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, sup-
     ported by Oath or affirmation, and particularly de-
     scribing the place to be searched, and the persons or
     things to be seized.”
That language does not state that warrants are required
prior to searches, but this Court has long held that war-
rants must generally be obtained. See Kentucky v. King,
563 U. S. ___, ___ (2011) (slip op., at 5). We have also held
that bodily intrusions like blood draws constitute searches
and are subject to the warrant requirement.               See
Schmerber v. California, 384 U. S. 757, 767, 770 (1966).
   However, “the ultimate touchstone of the Fourth
Amendment is ‘reasonableness,’ ” Brigham City v. Stuart,
547 U. S. 398, 403 (2006), and thus “the warrant require-
ment is subject to certain reasonable exceptions,” King,
563 U. S., at ___ (slip op., at 6). One of those exceptions is
known as the “exigent circumstances exception,” which
“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.” Ibid. (internal quotation marks and altera-
tions omitted).
   Within the exigent circumstances exception, we have
identified several sets of exigent circumstances excusing
the need for a warrant. For example, there is an emergency
aid exception to the warrant requirement. In Brigham
City, supra, at 403, we held that “law enforcement officers
may enter a home without a warrant to render emergency
                 Cite as: 569 U. S. ____ (2013)           3

                   Opinion of ROBERTS, C. J.

assistance to an injured occupant or to protect an occupant
from imminent injury.” There is also a fire exception to
the warrant requirement. In Michigan v. Tyler, 436 U. S.
499, 509 (1978), we held that “[a] burning building clearly
presents an exigency of sufficient proportions to render
a warrantless entry ‘reasonable.’ ” And there is a hot pur-
suit exception to the warrant requirement as well. In
United States v. Santana, 427 U. S. 38 (1976), and War-
den, Md. Penitentiary v. Hayden, 387 U. S. 294 (1967), we
recognized “the right of police, who had probable cause to
believe that an armed robber had entered a house a few
minutes before, to make a warrantless entry to arrest the
robber and to search for weapons.” Santana, supra, at 42.
In each of these cases, the requirement that we base our
decision on the “totality of the circumstances” has not
prevented us from spelling out a general rule for the police
to follow.
  The exigency exception most on point here is the one for
imminent destruction of evidence. We have affirmed on
several occasions that “law enforcement officers may make
a warrantless entry onto private property . . . to prevent
the imminent destruction of evidence.” Brigham City,
supra, at 403 (citing Ker v. California, 374 U. S. 23, 40
(1963) (plurality opinion)); see also, e.g., King, supra, at
___ (slip op., at 6). For example, in Ker, the police had
reason to believe that the defendant was in possession of
marijuana and was expecting police pursuit. We upheld
the officers’ warrantless entry into the defendant’s home,
with the plurality explaining that the drugs “could be
quickly and easily destroyed” or “distributed or hidden
before a warrant could be obtained at that time of night.”
374 U. S., at 40, 42.
  As an overarching principle, we have held that if there
is a “compelling need for official action and no time to
secure a warrant,” the warrant requirement may be ex-
4                  MISSOURI v. MCNEELY

                    Opinion of ROBERTS, C. J.

cused. Tyler, supra, at 509. The question here is whether
and how this principle applies in the typical case of a
police officer stopping a driver on suspicion of drunk
driving.
                                II

                                  

                                A

   The reasonable belief that critical evidence is being
destroyed gives rise to a compelling need for blood draws
in cases like this one. Here, in fact, there is not simply
a belief that any alcohol in the bloodstream will be de-
stroyed; it is a biological certainty. Alcohol dissipates from
the bloodstream at a rate of 0.01 percent to 0.025 percent
per hour. Stripp, Forensic and Clinical Issues in Alcohol
Analysis, in Forensic Chemistry Handbook 440 (L. Kobil-
insky ed. 2012). Evidence is literally disappearing by the
minute. That certainty makes this case an even stronger
one than usual for application of the exigent circumstances
exception.
   And that evidence is important. A serious and deadly
crime is at issue. According to the Department of Trans-
portation, in 2011, one person died every 53 minutes due
to drinking and driving. National Highway Traffic Safety
Admin. (NHTSA), Traffic Safety Facts, 2011 Data 1 (No.
811700, Dec. 2012). No surprise then that drinking and
driving is punished severely, including with jail time. See
generally Dept. of Justice, Bureau of Justice Statistics, L.
Maruschak, Special Report, DWI Offenders under Correc-
tional Supervision (1999). McNeely, for instance, faces up
to four years in prison. See App. 22–23 (citing Mo. Ann.
Stat. §§558.011, 577.010, 577.023 (West 2011)).
   Evidence of a driver’s blood alcohol concentration (BAC)
is crucial to obtain convictions for such crimes. All 50
States and the District of Columbia have laws providing
that it is per se illegal to drive with a BAC of 0.08 percent
or higher. Most States also have laws establishing addi-
                 Cite as: 569 U. S. ____ (2013)           5

                   Opinion of ROBERTS, C. J.

tional penalties for drivers who drive with a “high BAC,”
often defined as 0.15 percent or above. NHTSA, Digest
of Impaired Driving and Selected Beverage Control Laws,
pp. vii, x–xviii (No. 811673, Oct. 2012). BAC evidence
clearly matters. And when drivers refuse breathalyzers,
as McNeely did here, a blood draw becomes necessary to
obtain that evidence.
   The need to prevent the imminent destruction of BAC
evidence is no less compelling because the incriminating
alcohol dissipates over a limited period of time, rather
than all at once. As noted, the concentration of alcohol
 can make a difference not only between guilt and inno-
cence, but between different crimes and different degrees
of punishment. The officer is unlikely to know precisely
when the suspect consumed alcohol or how much; all he
knows is that critical evidence is being steadily lost. Fire
can spread gradually, but that does not lessen the need
and right of the officers to respond immediately. See
Tyler, supra.
   McNeely contends that there is no compelling need for a
warrantless blood draw, because if there is some alcohol
left in the blood by the time a warrant is obtained, the
State can use math and science to work backwards and
identify a defendant’s BAC at the time he was driving.
See Brief for Respondent 44–46. But that’s not good
enough. We have indicated that exigent circumstances
justify warrantless entry when drugs are about to be
flushed down the toilet. See, e.g., King, 563 U. S., at ___–
___ (slip op., at 7–8). We have not said that, because there
could well be drug paraphernalia elsewhere in the home,
or because a defendant’s co-conspirator might testify to
the amount of drugs involved, the drugs themselves are
not crucial and there is no compelling need for warrantless
entry.
   The same approach should govern here. There is a
6                       MISSOURI v. MCNEELY

                        Opinion of ROBERTS, C. J.

compelling need to search because alcohol—the nearly
conclusive evidence of a serious crime—is dissipating from
the bloodstream. The need is no less compelling because
the police might be able to acquire second-best evidence
some other way.1
                             B
  For exigent circumstances to justify a warrantless
search, however, there must also be “no time to secure a
warrant.” Tyler, 436 U. S., at 509; see Schmerber, 384
U. S., at 771 (warrantless search legal when “there was no
time to seek out a magistrate and secure a warrant”). In
this respect, obtaining a blood sample from a suspected
drunk driver differs from other exigent circumstances
cases.
  Importantly, there is typically delay between the mo-
ment a drunk driver is stopped and the time his blood can
be drawn. Drunk drivers often end up in an emergency
room, but they are not usually pulled over in front of one.
In most exigent circumstances situations, police are just
outside the door to a home. Inside, evidence is about to be
destroyed, a person is about to be injured, or a fire has
broken out. Police can enter promptly and must do so to
respond effectively to the emergency. But when police pull
a person over on suspicion of drinking and driving, they
cannot test his blood right away.2 There is a time-
——————
    1 Andthat second-best evidence may prove useless. When experts
have worked backwards to identify a defendant’s BAC at the time he
was driving, defense attorneys have objected to that evidence, courts
have at times rejected it, and juries may be suspicious of it. See, e.g., 1
D. Nichols & F. Whited, Drinking/Driving Litigation §2:9, pp. 2–130 to
2–137 (2d ed. 2006) (noting counsel objections to such evidence); State
v. Eighth Judicial District Court, 127 Nev. ___, 267 P. 3d 777 (2011)
(affirming rejection of such evidence); L. Taylor & S. Oberman, Drunk
Driving Defense §6.03 (7th ed. 2010) (describing ways to undermine
such evidence before a jury).
  2 This case involves medical personnel drawing blood at a medical
                     Cite as: 569 U. S. ____ (2013)                   7

                       Opinion of ROBERTS, C. J.

consuming obstacle to their search, in the form of a trip
to the hospital and perhaps a wait to see a medical pro-
fessional. In this case, for example, approximately 25
minutes elapsed between the time the police stopped
McNeely and the time his blood was drawn. App. 36, 38.
  As noted, the fact that alcohol dissipates gradually from
the bloodstream does not diminish the compelling need for
a search—critical evidence is still disappearing. But the
fact that the dissipation persists for some time means that
the police—although they may not be able to do anything
about it right away—may still be able to respond to the
ongoing destruction of evidence later on.
  There might, therefore, be time to obtain a warrant in
many cases. As the Court explains, police can often re-
quest warrants rather quickly these days. At least 30
States provide for electronic warrant applications. See
ante, at 10–12, and n. 4. In many States, a police officer
can call a judge, convey the necessary information, and be
authorized to affix the judge’s signature to a warrant.
See, e.g., Ala. Rule Crim. Proc. 3.8(b) (2012–2013); Alaska
Stat. §12.35.015 (2012); Idaho Code §§19–4404, 19–4406
(Lexis 2004); Minn. Rules Crim. Proc. 36.01–36.08 (2010
and Supp. 2013); Mont. Code Ann. §46–5–222 (2012); see
——————
facility, not police officers doing so by the side of the road. See
Schmerber v. California, 384 U. S. 757, 771–772 (1966) (“Petitioner’s
blood was taken by a physician in a hospital environment according to
accepted medical practices. We are thus not presented with the serious
questions which would arise if a search involving use of a medical
technique, even of the most rudimentary sort, were made by other than
medical personnel or in other than a medical environment—for exam-
ple, if it were administered by police in the privacy of the station-
house”); Brief for Respondent 53, and n. 21 (describing roadside blood
draws in Arizona). A plurality of the Court suggests that my approach
could make roadside blood draws a more attractive option for police,
but such a procedure would pose practical difficulties and, as the Court
noted in Schmerber, would raise additional and serious Fourth
Amendment concerns. See ante, at 14–15.
8                  MISSOURI v. MCNEELY

                   Opinion of ROBERTS, C. J.

generally NHTSA, Use of Warrants for Breath Test Re-
fusal: Case Studies 6–32 (No. 810852, Oct. 2007) (overview
of procedures in Arizona, Michigan, Oregon, and Utah).
Utah has an e-warrant procedure where a police officer
enters information into a system, the system notifies
a prosecutor, and upon approval the officer forwards
the information to a magistrate, who can electronically re-
turn a warrant to the officer. Utah, e-Warrants: Cross
Boundary Collaboration 1 (2008). Judges have been known
to issue warrants in as little as five minutes. Bergreen,
Faster Warrant System Hailed, Salt Lake Tribune, Dec.
26, 2008, p. B1, col. 1. And in one county in Kansas, police
officers can e-mail warrant requests to judges’ iPads;
judges have signed such warrants and e-mailed them back
to officers in less than 15 minutes. Benefiel, DUI Search
Warrants: Prosecuting DUI Refusals, 9 Kansas Prosecutor
17, 18 (Spring 2012). The police are presumably familiar
with the mechanics and time involved in the warrant
process in their particular jurisdiction.
                              III

                                 

                               A

  In a case such as this, applying the exigent circum-
stances exception to the general warrant requirement of
the Fourth Amendment seems straightforward: If there is
time to secure a warrant before blood can be drawn, the
police must seek one. If an officer could reasonably con-
clude that there is not sufficient time to seek and receive a
warrant, or he applies for one but does not receive a re-
sponse before blood can be drawn, a warrantless blood
draw may ensue. See Tyler, supra, at 509; see also Illinois
v. Rodriguez, 497 U. S. 177, 185–186 (1990) (“in order to
satisfy the ‘reasonableness’ requirement of the Fourth
Amendment, what is generally demanded of the many
factual determinations that must regularly be made by . . .
police officer[s] conducting a search or seizure under one of
                 Cite as: 569 U. S. ____ (2013)            9

                   Opinion of ROBERTS, C. J.

the exceptions to the warrant requirement . . . is not that
they always be correct, but that they always be reasona-
ble”); Terry v. Ohio, 392 U. S. 1, 20 (1968) (“police must,
whenever practicable, obtain advance judicial approval of
searches and seizures through the warrant procedure”).
   Requiring police to apply for a warrant if practicable
increases the likelihood that a neutral, detached judicial
officer will review the case, helping to ensure that there is
probable cause for any search and that any search is
reasonable. We have already held that forced blood draws
can be constitutional—that such searches can be reasonable—
but that does not change the fact that they are significant
bodily intrusions. See Schmerber, 384 U. S., at 770 (up-
holding a warrantless forced blood draw but noting the
“importance of informed, detached and deliberate deter-
minations of the issue whether or not to invade another’s
body in search of evidence of guilt” as “indisputable and
great”). Requiring a warrant whenever practicable helps
ensure that when blood draws occur, they are indeed
justified.
   At the same time, permitting the police to act without a
warrant to prevent the imminent destruction of evidence
is well established in Fourth Amendment law. There is no
reason to preclude application of that exception in drunk
driving cases simply because it may take the police some
time to be able to respond to the undoubted destruction of
evidence, or because the destruction occurs continuously
over an uncertain period.
   And that is so even in situations where police have
requested a warrant but do not receive a timely response.
An officer who reasonably concluded there was no time to
secure a warrant may have blood drawn from a suspect
upon arrival at a medical facility. There is no reason an
officer should be in a worse position, simply because he
sought a warrant prior to his arrival at the hospital.
10                 MISSOURI v. MCNEELY

                   Opinion of ROBERTS, C. J.

                             B
   The Court resists the foregoing, contending that the
question presented somehow inhibits such a focused anal-
ysis in this case. See ante, at 20–23. It does not. The
question presented is whether a warrantless blood draw is
permissible under the Fourth Amendment “based upon
the natural dissipation of alcohol in the bloodstream.”
Pet. for Cert. i. The majority answers “It depends,” and
so do I. The difference is that the majority offers no ad-
ditional guidance, merely instructing courts and police
officers to consider the totality of the circumstances. I
believe more meaningful guidance can be provided about
how to handle the typical cases, and nothing about the
question presented prohibits affording that guidance.
   A plurality of the Court also expresses concern that my
approach will discourage state and local efforts to expedite
the warrant application process. See ante, at 14. That is
not plausible: Police and prosecutors need warrants in a
wide variety of situations, and often need them quickly.
They certainly would not prefer a slower process, just
because that might obviate the need to ask for a warrant
in the occasional drunk driving case in which a blood draw
is necessary. The plurality’s suggestion also overlooks the
interest of law enforcement in the protection a warrant
provides.
   The Court is correct when it says that every case must
be considered on its particular facts. But the pertinent
facts in drunk driving cases are often the same, and the
police should know how to act in recurring factual situa-
tions. Simply put, when a drunk driving suspect fails field
sobriety tests and refuses a breathalyzer, whether a war-
rant is required for a blood draw should come down to
whether there is time to secure one.
   Schmerber itself provides support for such an analysis.
The Court there made much of the fact that “there was no
                 Cite as: 569 U. S. ____ (2013)         11

                   Opinion of ROBERTS, C. J.

time to seek out a magistrate and secure a warrant.” 384
U. S., at 771. It did so in an era when cell phones and
e-mail were unknown. It follows quite naturally that if
cell phones and e-mail mean that there is time to contact
a magistrate and secure a warrant, that must be done. At
the same time, there is no need to jettison the well-
established exception for the imminent destruction of
evidence, when the officers are in a position to do some-
thing about it.
                        *    *    *
  Because the Missouri courts did not apply the rule I
describe above, and because this Court should not do so in
the first instance, I would vacate and remand for further
proceedings in the Missouri courts.
                 Cite as: 569 U. S. ____ (2013)            1

                    THOMAS, J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

                         No. 11–1425
                         _________________


   MISSOURI, PETITIONER v. TYLER G. MCNEELY
    ON WRIT OF CERTIORARI TO THE SUPREME COURT OF 

                      MISSOURI


                        [April 17, 2013] 


  JUSTICE THOMAS, dissenting.
  This case requires the Court to decide whether the
Fourth Amendment prohibits an officer from obtaining a
blood sample without a warrant when there is probable
cause to believe that a suspect has been driving under the
influence of alcohol. Because the body’s natural meta­
bolization of alcohol inevitably destroys evidence of the
crime, it constitutes an exigent circumstance. As a result, I
would hold that a warrantless blood draw does not violate
the Fourth Amendment.
                             I

                             A

  The Fourth Amendment states that “[t]he right of the
people to be secure in their persons . . . against unreason­
able searches and seizures, shall not be violated, and no
Warrants shall issue, but upon probable cause.” Before a
search occurs, “a warrant must generally be secured,”
Kentucky v. King, 563 U. S. ___, ___ (2011) (slip op., at 5),
but “this presumption may be overcome in some circum­
stances because ‘[t]he ultimate touchstone of the Fourth
Amendment is “reasonableness.” ’ ” Ibid. (quoting Brig­
ham City v. Stuart, 547 U. S. 398, 403 (2006); alteration
in original).
  The presence of “exigent circumstances” is one such
exception to the warrant requirement. Exigency applies
2                  MISSOURI v. MCNEELY

                     THOMAS, J., dissenting

when “ ‘the needs of law enforcement [are] so compelling
that [a] warrantless search is objectively reasonable under
the Fourth Amendment.’ ” 563 U. S., at ___ (slip op., at 6)
(quoting Mincey v. Arizona, 437 U. S. 385, 394 (1978);
second alteration in original). Thus, when exigent circum­
stances are present, officers may take actions that would
typically require a warrant, such as entering a home in
hot pursuit of a fleeing suspect. 563 U. S., at ___ (slip op.,
at 6). As relevant in this case, officers may also conduct
a warrantless search when they have probable cause to
believe that failure to act would result in “ ‘imminent
destruction of evidence.’ ” Ibid. (quoting Brigham City,
supra, at 403).
                              B
   Once police arrest a suspect for drunk driving, each
passing minute eliminates probative evidence of the crime.
The human liver eliminates alcohol from the bloodstream
at a rate of approximately 0.015 percent to 0.020 percent
per hour, ante, at 8, with some heavy drinkers as high as
0.022 percent per hour, Brief for Petitioner 21 (citing
medical studies), depending on, among other things, a per-
son’s sex, weight, body type, and drinking history. Ante,
at 8–9; Brief for United States as Amicus Curiae 23.
The Court has acknowledged this fact since Schmerber v.
California, 384 U. S. 757, 770 (1966) (“We are told that the
percentage of alcohol in the blood begins to diminish shortly
after drinking stops, as the body functions to eliminate
it from the system”). In that case, the Court recognized
that destruction of evidence is inherent in drunk-driving
cases and held that an officer investigating a drunk­
driving crime “might reasonably [believe] that he [is]
confronted with an emergency, in which the delay neces­
sary to obtain a warrant, under the circumstances, threat­
en[s] ‘the destruction of evidence.’ ” Ibid. (quoting Preston
v. United States, 376 U. S. 364, 367 (1964)). The Court
                    Cite as: 569 U. S. ____ (2013)                   3

                        THOMAS, J., dissenting

explained that drawing a person’s blood is “a highly ef-
fective means of determining the degree to which [he] is
under the influence of alcohol” and is a reasonable proce­
dure because blood tests are “commonplace” and “involv[e]
virtually no risk, trauma, or pain.”1 384 U. S., at 771. The
Court, therefore, held that dissipation of alcohol in the
blood constitutes an exigency that allows a blood draw
without a warrant.
   The rapid destruction of evidence acknowledged by the
parties, the majority, and Schmerber’s exigency determi­
nation occurs in every situation where police have probable
cause to arrest a drunk driver. In turn, that destruction
of evidence implicates the exigent-circumstances doctrine.
See Cupp v. Murphy, 412 U. S. 291 (1973). In Cupp,
officers questioning a murder suspect observed a spot on
the suspect’s finger that they believed might be dried
blood. Id., at 292. After the suspect began making obvi­
ous efforts to remove the spots from his hands, the officers
took samples without obtaining either his consent or a
warrant. Id., at 296. Following a Fourth Amendment
challenge to this search, the Court held that the “ready
destructibility of the evidence” and the suspect’s observed
efforts to destroy it “justified the police in subjecting him
to the very limited search necessary to preserve the highly
evanescent evidence they found under his fingernails.”
Ibid.
   In this case, a similar exigency is present. Just as the
suspect’s efforts to destroy “highly evanescent evidence”
gave rise to the exigency in Cupp, the natural metaboliza­
tion of blood alcohol concentration (BAC) creates an exi­
gency once police have probable cause to believe the driver

——————
  1 Neither party has challenged this determination, which this Court
has reaffirmed several times. See, e.g., Skinner v. Railway Labor
Executives’ Assn., 489 U. S. 602, 625 (1989); Winston v. Lee, 470 U. S.
753, 761–763 (1985).
4                  MISSOURI v. MCNEELY

                    THOMAS, J., dissenting

is drunk. It naturally follows that police may conduct a
search in these circumstances.
   A hypothetical involving classic exigent circumstances
further illustrates the point. Officers are watching a
warehouse and observe a worker carrying bundles from
the warehouse to a large bonfire and throwing them into
the blaze. The officers have probable cause to believe
the bundles contain marijuana. Because there is only one
person carrying the bundles, the officers believe it will
take hours to completely destroy the drugs. During that
time the officers likely could obtain a warrant. But it is
clear that the officers need not sit idly by and watch the
destruction of evidence while they wait for a warrant. The
fact that it will take time for the evidence to be destroyed
and that some evidence may remain by the time the offi­
cers secure a warrant are not relevant to the exigency.
However, the ever-diminishing quantity of drugs may
have an impact on the severity of the crime and the
length of the sentence. See, e.g., 21 U. S. C. §841(b)(1)(D)
(lower penalties for less than 50 kilograms of marijuana);
United States Sentencing Commission, Guidelines Manual
§2D1.1(c) (Nov. 2012) (drug quantity table tying base
offense level to drug amounts). Conducting a warrantless
search of the warehouse in this situation would be entirely
reasonable.
   The same obtains in the drunk-driving context. Just
because it will take time for the evidence to be completely
destroyed does not mean there is no exigency. Congress
has conditioned federal highway grants on states’ adoption
of laws penalizing the operation of a motor vehicle “with a
blood alcohol concentration of 0.08 percent or greater.” 23
U. S. C. §163(a). See also 23 CFR §1225.1 (2012). All 50
States have acceded to this condition. National Highway
Traffic Safety Admin. (NHTSA), Alcohol and Highway
Safety: A Review of the State of Knowledge 167 (No.
811374, Mar. 2011) (NHTSA State Review); Mo. Ann.
                 Cite as: 569 U. S. ____ (2013)           5

                    THOMAS, J., dissenting

Stat. §§577.012(1)–(2) (West 2011) (establishing Missouri’s
0.08 percent BAC standard). Moreover, as of 2005, 32
States and the District of Columbia imposed additional
penalties for BAC levels of 0.15 percent or higher. NHTSA
State Review 175. Missouri is one such State. See, e.g.,
Mo. Stat. Ann. §§577.010(3)–(4), 577.012(4)–(5) (suspended
sentence unavailable even for first offenders with BAC
above 0.15 percent unless they complete drug treatment;
mandatory jail time if treatment is not completed). As a
result, the level of intoxication directly bears on enforce­
ment of these laws. Nothing in the Fourth Amendment
requires officers to allow evidence essential to enforcement
of drunk-driving laws to be destroyed while they wait for a
warrant to issue.
                              II
  In today’s decision, the Court elides the certainty of
evidence destruction in drunk-driving cases and focuses
primarily on the time necessary for destruction. In doing
so, it turns the exigency inquiry into a question about the
amount of evidentiary destruction police must permit
before they may act without a warrant. That inquiry is
inconsistent with the actual exigency at issue: the un­
contested destruction of evidence due to metabolization of
alcohol. See Part I, supra. Moreover, the Court’s facts­
and-circumstances analysis will be difficult to administer,
a particularly important concern in the Fourth Amend­
ment context.
  The Court’s judgment reflects nothing more than a
vague notion that everything will come out right most of
the time so long as the delay is not too lengthy. Ante, at
12 (justifying delays in part because “BAC evidence is lost
gradually and relatively predictably”); ante, at 10 (same,
quoting Brief for Petitioner 27). But hard percentage lines
have meaningful legal consequences in the drunk-driving
context. The fact that police will be able to retrieve some
6                   MISSOURI v. MCNEELY

                     THOMAS, J., dissenting

evidence before it is all destroyed is simply not relevant to
the exigency inquiry.
   The majority believes that, absent special facts and
circumstances, some destruction of evidence is acceptable.
See ante, at 9 (“sufficient for our purposes to note that . . .
significant delay in testing will negatively affect the pro­
bative value” (emphasis added)). This belief must rest
on the assumption that whatever evidence remains once a
warrant is obtained will be sufficient to prosecute the
suspect. But that assumption is clearly wrong. Suspects’
initial levels of intoxication and the time necessary to
obtain warranted blood draws will vary widely from case
to case. Even a slight delay may significantly affect pro­
bative value in borderline cases of suspects who are mod­
erately intoxicated or suspects whose BAC is near a statu­
tory threshold that triggers a more serious offense. See
supra, at 4–5 (discussing laws penalizing heightened BAC
levels). Similarly, the time to obtain a warrant can be ex­
pected to vary, and there is no reason to believe it will
do so in a predictable fashion.
   Further, the Court nowhere explains how an officer in
the field is to apply the facts-and-circumstances test it
adopts. First, officers do not have the facts needed to
assess how much time can pass before too little evidence
remains. They will never know how intoxicated a suspect
is at the time of arrest. Otherwise, there would be no need
for testing. Second, they will not know how long it will
take to roust a magistrate from his bed, reach the hospital,
or obtain a blood sample once there. As the Minnesota
Supreme Court recognized in rejecting arguments like
those adopted by the Court today:
    “[T]he officer has no control over how long it would
    take to travel to a judge or the judge’s availability.
    The officer also may not know the time of the sus­
    pect’s last drink, the amount of alcohol consumed, or
                     Cite as: 569 U. S. ____ (2013)                     7

                         THOMAS, J., dissenting

     the rate at which the suspect will metabolize alcohol.
     Finally, an officer cannot know how long it will take to
     obtain the blood sample once the suspect is brought
     to the hospital. Under a totality of the circumstances
     test, an officer would be called upon to speculate on
     each of these considerations and predict how long the
     most probative evidence of the defendant’s blood­
     alcohol level would continue to exist before a blood
     sample was no longer reliable.” State v. Shriner, 751
     N. W. 2d 538, 549 (2008) (footnote omitted).
The Court should not adopt a rule that requires police to
guess whether they will be able to obtain a warrant before
“too much” evidence is destroyed, for the police lack reli-
able information concerning the relevant variables.2
   This case demonstrates the uncertainty officers face
with regard to the delay caused by obtaining a warrant.
The arresting officer clearly had probable cause to believe
respondent was drunk, but there was no way for the of­
ficer to quantify the level of intoxication to determine how
quickly he needed to act in order to obtain probative evi­
dence. Another officer testified at respondent’s trial that
it typically took 1 ½ to 2 hours to obtain a drunk-driving
warrant at night in Cape Girardeau County, Missouri.
See App. 53–54. Respondent submitted an exhibit sum­
marizing six late afternoon and nighttime drunk-driving
search warrants that suggests the time may be shorter.
——————
  2 Because the Court’s position is likely to result in delay in obtaining

BAC evidence, it also increases the likelihood that prosecutors will be
forced to estimate the amount of alcohol in a defendant’s bloodstream
using BAC numbers obtained hours later. In practice, this backwards
extrapolation is likely to devolve into a battle of the experts, as each
side seeks to show that stale evidence supports its position. There is no
need for this outcome. Police facing inevitable destruction situations
need not forgo collecting the most accurate available evidence simply
because they might be able to use an expert witness and less persuasive
evidence to approximate what they lost.
8                    MISSOURI v. MCNEELY

                       THOMAS, J., dissenting

Brief for Respondent 56; App. 70. Ultimately this factual
tiff is beside the point; the spotty evidence regarding
timing itself illustrates the fact that delays in obtaining
warrants are unpredictable and potentially lengthy. A
rule that requires officers (and ultimately courts) to bal­
ance transportation delays, hospital availability, and ac-
cess to magistrates is not a workable rule for cases where
natural processes inevitably destroy the evidence with
every passing minute.
   The availability of telephonic warrant applications is
not an answer to this conundrum. See ante, at 10–12,
and n. 4. For one thing, Missouri still requires written
warrant applications and affidavits, Mo. Ann. Stat.
§§542.276.2(1), 542.276.2.3 (West Supp. 2012), rendering
the Court’s 50-State survey irrelevant to the actual dispo­
sition of this case. Ante, at 11, n. 4. But even if telephonic
applications were available in Missouri, the same difficul­
ties would arise. As the majority correctly recognizes,
“[w]arrants inevitably take some time for police officers
or prosecutors to complete and for magistrate judges to
review.” Ante, at 12. During that time, evidence is de­
stroyed, and police who have probable cause to believe a
crime has been committed should not have to guess how
long it will take to secure a warrant.

                          *    *    * 

    For the foregoing reasons, I respectfully dissent. 

