When stopped in unrelated incidents on suspicion of drunken
driving on California highways, each respondent submitted to a
Intoxilyzer (breath analysis) test and registered a blood-alcohol
concentration high enough to be presumed to be intoxicated under
California law. Although it was technically feasible to preserve
samples of respondents' breath, the arresting officers, as was
their ordinary practice, did not do so. Respondents were then all
charged with driving while intoxicated. Prior to trial, the
Municipal Court denied each respondent's motion to suppress the
Intoxilyzer test results on the ground that the arresting officers
had failed to preserve samples of respondents' breath that the
respondents claim would have enabled them to impeach the
incriminating test results. Ultimately, in consolidated
proceedings, the California Court of Appeal ruled in respondents'
favor, concluding that due process demanded that the arresting
officers preserve the breath samples.
Held: The Due Process Clause of the Fourteenth
Amendment does not require that law enforcement agencies preserve
breath samples in order to introduce the results of breath analysis
tests at trial, and thus, here, the State's failure to preserve
breath samples for respondents did not constitute a violation of
the Federal Constitution. Pp.
467 U. S.
485-491.
(a) To the extent that respondents' breath samples came into the
California authorities' possession, it was for the limited purpose
of providing raw data to the Intoxilyzer. The evidence to be
presented at trial was not the breath itself, but rather the
Intoxilyzer results obtained from the breath samples. The
authorities did not destroy the breath samples in a calculated
effort to circumvent the due process requirement of
Brady v.
Maryland, 373 U. S. 83, and
its progeny that the State disclose to criminal defendants material
evidence in its possession, but in failing to preserve the samples,
the authorities acted in good faith and in accord with their normal
practice. Pp.
467 U. S.
485-488.
(b) More importantly, California's policy of not preserving
breath samples is without constitutional defect. The constitutional
duty of the States to preserve evidence is limited to evidence that
might be expected to play a role in the suspect's defense. The
evidence must possess an exculpatory value that was apparent before
it was destroyed, and must also be of such a nature that the
defendant would be unable to obtain
Page 467 U. S. 480
comparable evidence by other reasonably available means. Neither
of these conditions was met on the facts of this case. Pp.
467 U. S.
488-490.
142 Cal. App.
3d 138,
190 Cal. Rptr.
319, reversed and remanded.
MARSHALL, J., delivered the opinion for a unanimous Court.
O'CONNOR, J., filed a concurring opinion,
post, p.
467 U. S.
491.
JUSTICE MARSHALL delivered the opinion of the Court.
The Due Process Clause of the Fourteenth Amendment requires the
State to disclose to criminal defendants favorable evidence that is
material either to guilt or to punishment.
United States v.
Agurs, 427 U. S. 97
(1976);
Brady v.
Page 467 U. S. 481
Maryland, 373 U. S.
83 (1963). This case raises the question whether the
Fourteenth Amendment also demands that the State preserve
potentially exculpatory evidence on behalf of defendants. In
particular, the question presented is whether the Due Process
Clause requires law enforcement agencies to preserve breath samples
of suspected drunken drivers in order for the results of breath
analysis tests to be admissible in criminal prosecutions.
I
The Omicron Intoxilyzer (Intoxilyzer) is a device used in
California to measure the concentration of alcohol in the blood of
motorists suspected of driving while under the influence of
intoxicating liquor. [
Footnote
1] The Intoxilyzer analyzes the suspect's breath. To operate
the device, law enforcement officers follow these procedures:
"Prior to any test, the device is purged by pumping clean air
through it until readings of 0.00 are obtained. The breath test
requires a sample of 'alveolar' (deep lung) air; to assure that
such a sample is obtained, the subject is required to blow air into
the intoxilyzer at a constant pressure for a period of several
seconds. A breath sample is captured in the intoxilyzer's chamber
and infrared light is used to sense the alcohol level. Two samples
are taken, and the result of each is indicated on a printout card.
The two tests must register within 0.02 of each other in order to
be admissible in court. After each test, the chamber is purged with
clean air, and then
Page 467 U. S. 482
checked for a reading of zero alcohol. The machine is calibrated
weekly, and the calibration results, as well as a portion of the
calibration samples, are available to the defendant."
142 Cal. App.
3d 138, 141-142,
190 Cal. Rptr.
319, 321 (1983) (citations omitted).
In unrelated incidents in 1980 and 1981, each of the respondents
in this case was stopped on suspicion of drunken driving on
California highways. Each respondent submitted to an Intoxilyzer
test. [
Footnote 2] Each
respondent registered a blood alcohol concentration substantially
higher than 0.10 percent. Under California law at that time,
drivers with higher than 0.10 percent blood alcohol concentrations
were presumed to be intoxicated. Cal.Veh.Code Ann. § 23126(a)(3)
(West 1971) (amended 1981). Respondents were all charged with
driving while intoxicated in violation of Cal.Veh.Code Ann. 23102
(West 1971) (amended 1981).
Prior to trial in Municipal Court, each respondent filed a
motion to suppress the Intoxilyzer test results on the ground that
the arresting officers had failed to preserve samples of
respondents' breath. Although preservation of breath samples is
technically feasible, [
Footnote
3] California law enforcement officers
Page 467 U. S. 483
do not ordinarily preserve breath samples, and made no effort to
do so in these cases. Respondents each claimed that, had a breath
sample been preserved, he would have been able to impeach the
incriminating Intoxilyzer results. All of respondents' motions to
suppress were denied. Respondents Ward and Berry then submitted
their cases on the police records, and were convicted. Ward and
Berry subsequently petitioned the California Court of Appeal for
writs of habeas corpus. Respondents Trombetta and Cox did not
submit to trial. They sought direct appeal from the Municipal Court
orders, and their appeals were eventually transferred to the Court
of Appeal to be consolidated with the Ward and Berry petitions.
[
Footnote 4]
The California Court of Appeal ruled in favor of respondents.
After implicitly accepting that breath samples would be useful to
respondents' defenses, the court reviewed the available
technologies and determined that the arresting officers had the
capacity to preserve breath samples for respondents. 142 Cal. App.
3d at 141-142, 190 Cal. Rptr. at 320-321. Relying heavily on the
California Supreme Court's decision in
People v.
Hitch, 12 Cal. 3d
641, 527 P.2d 361 (1974), the Court of Appeal concluded:
"Due process demands simply that, where evidence is collected by
the state, as it is with the intoxilyzer or any other breath
testing device, law enforcement agencies must establish and follow
rigorous and
Page 467 U. S. 484
systematic procedures to preserve the captured evidence or its
equivalent for the use of the defendant."
142 Cal. App. 3d at 144, 190 Cal. Rptr. at 323. [
Footnote 5] The court granted respondents
Ward and Berry new trials, and ordered that the Intoxilyzer results
not be admitted as evidence against the other two respondents. The
State unsuccessfully petitioned for certiorari in the California
Supreme Court, and then petitioned for review in this Court. We
granted certiorari, 464 U.S. 1037 (1984), and now reverse.
Page 467 U. S. 485
II
Under the Due Process Clause of the Fourteenth Amendment,
criminal prosecutions must comport with prevailing notions of
fundamental fairness. We have long interpreted this standard of
fairness to require that criminal defendants be afforded a
meaningful opportunity to present a complete defense. To safeguard
that right, the Court has developed "what might loosely be called
the area of constitutionally guaranteed access to evidence."
United States v. Valenzuela-Bernal, 458 U.
S. 858,
458 U. S. 867
(1982). Taken together, this group of constitutional privileges
delivers exculpatory evidence into the hands of the accused,
thereby protecting the innocent from erroneous conviction and
ensuring the integrity of our criminal justice system.
The most rudimentary of the access-to-evidence cases impose upon
the prosecution a constitutional obligation to report to the
defendant and to the trial court whenever government witnesses lie
under oath.
Napue v. Illinois, 360 U.
S. 264,
360 U. S.
269-272 (1959);
see also Mooney v. Holohan,
294 U. S. 103
(1935). But criminal defendants are entitled to much more than
protection against perjury. A defendant has a constitutionally
protected privilege to request and obtain from the prosecution
evidence that is either material to the guilt of the defendant or
relevant to the punishment to be imposed.
Brady v.
Maryland, 373 U.S. at
373 U. S. 87. Even in the absence of a specific request,
the prosecution has a constitutional duty to turn over exculpatory
evidence that would raise a reasonable doubt about the defendant's
guilt.
United States v. Agurs, 427 U.S. at
427 U. S. 112.
The prosecution must also reveal the contents of plea agreements
with key government witnesses,
see Giglio v. United
States, 405 U. S. 150
(1972), and, under some circumstances, may be required to disclose
the identity of undercover informants who possess evidence critical
to the defense,
Roviaro v. United States, 353 U. S.
53 (1957).
Page 467 U. S. 486
Less clear from our access-to-evidence cases is the extent to
which the Due Process Clause imposes on the government the
additional responsibility of guaranteeing criminal defendants
access to exculpatory evidence beyond the government's possession.
On a few occasions, we have suggested that the Federal Government
might transgress constitutional limitations if it exercised its
sovereign powers so as to hamper a criminal defendant's preparation
for trial. For instance, in
United States v. Marion,
404 U. S. 307,
404 U. S. 324
(1971), and in
United States v. Lovasco, 431 U.
S. 783,
431 U. S. 795,
n. 17 (1977), we intimated that a due process violation might occur
if the Government delayed an indictment for so long that the
defendant's ability to mount an effective defense was impaired.
Similarly, in
United States v. Valenzuela-Bernal, supra,
we acknowledged that the Government could offend the Due Process
Clause of the Fifth Amendment if, by deporting potential witnesses,
it diminished a defendant's opportunity to put on an effective
defense. [
Footnote 6] 458 U.S.
at
458 U. S.
873.
We have, however, never squarely addressed the government's duty
to take affirmative steps to preserve evidence on behalf of
criminal defendants. The absence of doctrinal development in this
area reflects, in part, the difficulty of developing rules to deal
with evidence destroyed through prosecutorial neglect or oversight.
Whenever potentially exculpatory evidence is permanently lost,
courts face the treacherous task of divining the import of
materials whose contents are unknown and, very often, disputed.
Cf. United States v. Valenzuela-Bernal, supra, at
458 U. S. 870.
Moreover, fashioning remedies for the illegal destruction of
evidence can pose troubling choices. In nondisclosure cases, a
court can
Page 467 U. S. 487
grant the defendant a new trial at which the previously
suppressed evidence may be introduced. But when evidence has been
destroyed in violation of the Constitution, the court must choose
between barring further prosecution or suppressing -- as the
California Court of Appeal did in this case -- the State's most
probative evidence.
One case in which we have discussed due process constraints on
the Government's failure to preserve potentially exculpatory
evidence is
Killian v. United States, 368 U.
S. 231 (1961). In
Killian, the petitioner had
been convicted of giving false testimony in violation of 18 U.S.C.
§ 1001. A key element of the Government's case was an investigatory
report prepared by the Federal Bureau of Investigation. The
Solicitor General conceded that, prior to petitioner's trial, the
F.B.I. agents who prepared the investigatory report destroyed the
preliminary notes they had made while interviewing witnesses. The
petitioner argued that these notes would have been helpful to his
defense and that the agents had violated the Due Process Clause by
destroying this exculpatory evidence. While not denying that the
notes might have contributed to the petitioner's defense, the Court
ruled that their destruction did not rise to the level of
constitutional violation:
"If the agents' notes . . . were made only for the purpose of
transferring the data thereon . . . and if, having served that
purpose, they were destroyed by the agents in good faith and in
accord with their normal practices, it would be clear that their
destruction did not constitute an impermissible destruction of
evidence nor deprive petitioner of any right."
Id. at 242.
In many respects, the instant case is reminiscent of
Killian
v. United States. To the extent that respondents' breath
samples came into the possession of California authorities, it was
for the limited purpose of providing raw data to the
Page 467 U. S. 488
Intoxilyzer. [
Footnote 7]
The evidence to be presented at trial was not the breath itself,
but rather the Intoxilyzer results obtained from the breath
samples. As the petitioner in
Killian wanted the agents'
notes in order to impeach their final reports, respondents here
seek the breath samples in order to challenge incriminating tests
results produced with the Intoxilyzer.
Given our precedents in this area, we cannot agree with the
California Court of Appeal that the State's failure to retain
breath samples for respondents constitutes a violation of the
Federal Constitution. To begin with, California authorities in this
case did not destroy respondents' breath samples in a calculated
effort to circumvent the disclosure requirements established by
Brady v. Maryland and its progeny. In failing to preserve
breath samples for respondents, the officers here were acting "in
good faith and in accord with their normal practice."
Killian
v. United States, supra, at
368 U. S. 242.
The record contains no allegation of official animus towards
respondents or of a conscious effort to suppress exculpatory
evidence.
More importantly, California's policy of not preserving breath
samples is without constitutional defect. Whatever duty the
Constitution imposes on the States to preserve evidence, that duty
must be limited to evidence that might be expected to play a
significant role in the suspect's defense. [
Footnote 8]
Page 467 U. S. 489
To meet this standard of constitutional materiality,
see
United States v. Agurs, 427 U.S. at
427 U. S.
109-110, evidence must both possess an exculpatory value
that was apparent before the evidence was destroyed and be of such
a nature that the defendant would be unable to obtain comparable
evidence by other reasonably available means. Neither of these
conditions is met on the facts of this case.
Although the preservation of breath samples might conceivably
have contributed to respondents' defenses, a dispassionate review
of the Intoxilyzer and the California testing procedures can only
lead one to conclude that the chances are extremely low that
preserved samples would have been exculpatory. The accuracy of the
Intoxilyzer has been reviewed and certified by the California
Department of Health. [
Footnote
9] To protect suspects against machine malfunctions, the
Department has developed test procedures that include two
independent measurements (which must be closely correlated for the
results to be admissible) bracketed by blank runs designed to
ensure that the machine is purged of alcohol traces from previous
tests.
See supra at
467 U. S.
481-482. In all but a tiny fraction of cases, preserved
breath samples would simply confirm the Intoxilyzer's determination
that the defendant had a high level of blood alcohol concentration
at the time of the test. Once the Intoxilyzer indicated that
respondents were legally drunk, breath samples were much more
likely to provide inculpatory than exculpatory evidence. [
Footnote 10]
Page 467 U. S. 490
Even if one were to assume that the Intoxilyzer results in this
case were inaccurate, and that breath samples might therefore have
been exculpatory, it does not follow that respondents were without
alternative means of demonstrating their innocence. Respondents and
amici have identified only a limited number of ways in
which an Intoxilyzer might malfunction: faulty calibration,
extraneous interference with machine measurements, and operator
error.
See Brief for Respondents 32-34; Brief for
California Public Defender's Association
et al. as
Amici Curiae 25-40. Respondents were perfectly capable of
raising these issues without resort to preserved breath samples. To
protect against faulty calibration, California gives drunken
driving defendants the opportunity to inspect the machine used to
test their breath, as well as that machine's weekly calibration
results and the breath samples used in the calibrations.
See
supra at
467 U. S.
481-482. Respondents could have utilized these data to
impeach the machine's reliability. As to improper measurements, the
parties have identified only two sources capable of interfering
with test results: radio waves and chemicals that appear in the
blood of those who are dieting. For defendants whose test results
might have been affected by either of these factors, it remains
possible to introduce at trial evidence demonstrating that the
defendant was dieting at the time of the test or that the test was
conducted near a source of radio waves. Finally, as to operator
error, the defendant retains the right to cross-examine the law
enforcement officer who administered the Intoxilyzer test, and to
attempt to raise doubts in the mind of the factfinder whether the
test was properly administered. [
Footnote 11]
Page 467 U. S. 491
III
We conclude, therefore, that the Due Process Clause of the
Fourteenth Amendment does not require that law enforcement agencies
preserve breath samples in order to introduce the results of breath
analysis tests at trial. [
Footnote 12] Accordingly, the judgment of the California
Court of Appeal is reversed, and the case is remanded for further
proceedings not inconsistent with this opinion.
It is so ordered.
[
Footnote 1]
Law enforcement agencies in California are obliged to use breath
analysis equipment that has been approved by the State's Department
of Health.
See 17 Cal.Admin.Code § 1221 (1976). The
Department has approved a number of blood alcohol testing devices
employing a variety of technologies,
see List of
Instruments and Related Accessories Approved for Breath Alcohol
Analysis (Dec. 20, 1979), reprinted in App. 238-247, of which the
Omicron Intoxilyzer is the most popular model,
see Brief
for Petitioner 6, n. 6.
[
Footnote 2]
Under California law, drunken driving suspects are given the
choice of having their blood alcohol concentration determined by
either a blood test, a urine test, or a breath test. Cal.Veh.Code
Ann. § 13353 (West 1971 and Supp.1984). Suspects who refuse to
submit to any test are liable to have their driving licenses
suspended.
Ibid.
[
Footnote 3]
The California Department of Health has approved a device, known
as an Intoximeter Field Crimper-Indium Tube Encapsulation Kit
(Kit), which officers can use to preserve breath samples. App. 247.
To use the Kit, a suspect must breathe directly into an indium
tube, which preserves samples in three separate chambers.
See 142 Cal. App.
3d 138, 142,
190 Cal. Rptr.
319, 321 (1983). The breath trapped in each chamber can later
be used to determine the suspect's blood alcohol concentration
through the use of a laboratory instrument known as a Gas
Chromatograph Intoximeter, which has also been approved by the
California Department of Health. App. 242-243. Because the suspect
must breathe directly into the indium tube, the Kit cannot be used
to preserve the same breath sample used in an Intoxilyzer test.
See supra at
467 U. S.
481-482. Other devices, similar in function to the Kit,
can be attached to an Intoxilyzer and used to collect the air that
the Intoxilyzer purges,
see Brief for Respondents 18-19,
but none of these devices has yet received approval from the
California Department of Health,
see Reply Brief for
Petitioner 3-4.
[
Footnote 4]
The California Court of Appeal expressed some doubt whether
respondents Trombetta and Cox were entitled to appeal their
suppression orders, and ultimately ordered that their appeals be
dismissed. 142 Cal. App. 3d at 140, 143, 190 Cal. Rptr. at 320,
323. The court, however, ruled on the merits of their claims, and
thereby exercised jurisdiction over their appeals.
Id. at
144, 190 Cal. Rptr. at 323. As to Trombetta and Cox, the Court of
Appeal decision was comparable to a judgment affirming a
suppression order, which is reviewable in this Court under 28
U.S.C. § 1257(3).
Cf., e.g., Michigan v. Clifford,
464 U. S. 287
(1984).
[
Footnote 5]
People v. Hitch involved another device used to measure
blood alcohol concentrations. With that device, a suspect's breath
bubbles through a glass ampoule containing special chemicals that
change colors depending on the amount of alcohol in the suspect's
blood. 12 Cal. 3d at 644, 527 P.2d at 363-364. In keeping with
California procedures, law enforcement officials in
Hitch
discarded the ampoule after they had completed their testing, even
though the ampoule might have been saved for retesting by the
defendant. Relying on this Court's decisions in
Brady v.
Maryland, 373 U. S. 83
(1963), and
Giglio v. United States, 405 U.
S. 150,
405 U. S.
153-154 (1972), the California Supreme Court concluded
that the Due Process Clause is implicated when a State
intentionally destroys evidence that might have proved favorable to
a criminal defendant. 12 Cal. 3d at 645-650, 527 P.2d at 364-370.
The
Hitch decision was noteworthy in that it extrapolated
from
Brady's disclosure requirement an additional
constitutional duty on the part of prosecutors to preserve
potentially exculpatory evidence.
See Note, The Right to
Independent Testing: A New Hitch in the Preservation of Evidence
Doctrine, 75 Colum.L.Rev. 1355, 1364-1368 (1975);
cf. United
States v. Bryant, 142 U.S.App.D.C. 132, 141, 439 F.2d 642, 651
(1971) (Wright, J.) (Government must make "
earnest efforts' to
preserve crucial materials and to find them once a discovery
request is made").
For a number of years, there was uncertainty whether the
California courts would extend the
Hitch decision to the
Intoxilyzer. In
People v. Miller, 52 Cal. App. 3d
666, 125 Cal. Rptr. 341 (1975), a Court of Appeal panel refused
to extend
Hitch because the Intoxilyzer does not reduce
breath samples to a preservable form comparable to the ampoules
created with the device involved in
Hitch. The Court of
Appeal in
Trombetta declined to follow
Miller,
and reasoned that, as long as there were other methods of
preserving specimens (such as the Indium Tube Kit,
see
n 3,
supra), the State
was obliged to preserve a breath sample equivalent to the one used
in the Intoxilyzer. 142 Cal. App. 3d at 143-144, 190 Cal. Rptr. at
322-323.
[
Footnote 6]
In related cases arising under the Sixth and Fourteenth
Amendments, we have recognized that criminal defendants are
entitled to call witnesses on their own behalf and to cross-examine
witnesses who have testified on the government's behalf.
See
Davis v. Alaska, 415 U. S. 308
(1974);
Washington v. Texas, 388 U. S.
14 (1967).
[
Footnote 7]
We accept the California Court of Appeal's conclusion that the
Intoxilyzer procedure brought respondents' breath samples into the
possession of California officials. The capacity to preserve breath
samples is equivalent to the actual possession of samples.
See n 5,
supra.
[
Footnote 8]
In our prosecutorial disclosure cases, we have imposed a similar
requirement of materiality,
United States v. Agurs,
427 U. S. 97
(1976), and have rejected the notion that a "prosecutor has a
constitutional duty routinely to deliver his entire file to defense
counsel."
Id. at
427 U. S. 111;
see also Moore v. Illinois, 408 U.
S. 786,
408 U. S. 795
(1972) ("We know of no constitutional requirement that the
prosecution make a complete and detailed accounting to the defense
of all police investigatory work on a case").
[
Footnote 9]
The Intoxilyzer has also passed accuracy requirements
established by the National Highway Traffic Safety Administration
of the Department of Transportation.
See 38 Fed.Reg. 30459
(1973); A. Flores, Results of the First Semi-Annual Qualification
Testing of Devices to Measure Breath Alcohol 10 (Dept. of
Transportation 1975).
[
Footnote 10]
The materiality of breath samples is directly related to the
reliability of the Intoxilyzer itself. The degree to which
preserved samples are material depends on how reliable the
Intoxilyzer is. This correlation suggests that a more direct
constitutional attack might be made on the sufficiency of the
evidence underlying the State's case. After all, if the Intoxilyzer
were truly prone to erroneous readings, then Intoxilyzer results,
without more, might be insufficient to establish guilt beyond a
reasonable doubt.
Jackson v. Virginia, 443 U.
S. 307 (1979).
[
Footnote 11]
Respondents could also have protected themselves from erroneous
on-the-scene testing by electing to submit to urine or blood tests,
see n 2,
supra, because the State automatically would have
preserved urine and blood samples for retesting by respondents.
Respondents, however, were not informed of the difference between
the various testing procedures when they were asked to select among
the three available methods of testing blood alcohol
concentrations.
But see Cal.Veh.Code Ann. § 13353.5 (West
1971) (enacted in 1983) (requiring suspects to be informed that
samples will be retained only in urine and blood tests). To the
extent that this and other access-to-evidence cases turn on the
underlying fairness of governmental procedures, it would be
anomalous to permit the State to justify its actions by relying on
procedural alternatives that were available, but unknown to the
defendant. Similarly, it is irrelevant to our inquiry that
California permits an accused drunken driver to have a second blood
alcohol test conducted by independent experts, since there is no
evidence on this record that respondents were aware of this
alternative.
[
Footnote 12]
State courts and legislatures, of course, remain free to adopt
more rigorous safeguards governing the admissibility of scientific
evidence than those imposed by the Federal Constitution.
See,
e.g., Lauderdale v. State, 548 P.2d 376
(Alaska 1976);
City of Lodi v. Hine, 107 Wis.2d 118,
318 N.W.2d
383 (1982).
JUSTICE O'CONNOR, concurring.
Rules concerning preservation of evidence are generally matters
of state, not federal constitutional, law.
See United States v.
Augenblick, 393 U. S. 348,
393 U. S.
352-353 (1969). The failure to preserve breath samples
does not render a prosecution fundamentally unfair, and thus cannot
render breath analysis tests inadmissible as evidence against the
accused.
Id. at
393 U. S. 356.
Similarly, the failure to employ alternative methods of testing
blood alcohol concentrations is of no due
Page 467 U. S. 492
process concern, both because persons are presumed to know their
rights under the law and because the existence of tests not used in
no way affects the fundamental fairness of the convictions actually
obtained. I understand the Court to state no more than these
well-settled propositions. Accordingly, I join both its opinion and
judgment.