v. Marston , 2021 COA 14 ( 2021 )

The summaries of the Colorado Court of Appeals published opinions
constitute no part of the opinion of the division but have been prepared by
the division for the convenience of the reader. The summaries may not be
cited or relied upon as they are not the official language of the division.
Any discrepancy between the language in the summary and in the opinion
should be resolved in favor of the language in the opinion.
SUMMARY
February 11, 2021
2021COA14
No. 18CA1879, People v. Marston — Crimes — DWAI;
Evidence — Admissibility
A division of the court of appeals holds that a trial court may
admit evidence of the results of a horizontal gaze nystagmus test
given to a motorist without first holding a Shreck hearing, if the
evidence is offered only as evidence of impairment and if the
witness testifying about the administration and the results of the
test is competent to give such testimony.
COLORADO COURT OF APPEALS 2021COA14
Court of Appeals No. 18CA1879
Jefferson County District Court No. 16CR2934
Honorable Tamara S. Russell, Judge
The People of the State of Colorado,
Plaintiff-Appellee,
v.
Shawn Patrick Marston,
Defendant-Appellant.
JUDGMENT REVERSED AND CASE
REMANDED WITH DIRECTIONS
Division V
Opinion by JUDGE J. JONES
Welling and Gomez, JJ., concur
Announced February 11, 2021
Philip J. Weiser, Attorney General, Frank R. Lawson, Assistant Attorney
General, Denver, Colorado, for Plaintiff-Appellee
Megan A. Ring, Colorado State Public Defender, Meredith E. O’Harris, Deputy
State Public Defender, Denver, Colorado, for Defendant-Appellant
¶1 Defendant, Shawn Patrick Marston, appeals the judgment of
conviction entered on a jury verdict finding him guilty of driving
while ability impaired (DWAI). One of the issues he raises is
whether the district court was required to hold a Shreck hearing,
see People v. Shreck, 22 P.3d 68 (Colo. 2001), before allowing a
police officer to testify about the results of a horizontal gaze
nystagmus (HGN) test the officer administered to him immediately
before he was arrested. We previously issued an opinion holding
that no such hearing was required; the results of such a test are
generally admissible, if relevant, as evidence of impairment, so long
as the person testifying about the administration and results of the
test is competent to give such testimony. The officer in this case
was, so the court didn’t err by allowing the officer’s testimony.
People v. Marston, 2020 COA 121. We also rejected Marston’s other
challenges to the judgment, including his contention that the
district court erred by finding by a preponderance of the evidence
that he had at least three prior alcohol-related driving convictions
rather than submitting that issue to the jury for it to decide beyond
a reasonable doubt.
1
¶2 The supreme court vacated our opinion and remanded the
case for reconsideration in light of its decision in Linnebur v. People,
2020 CO 79M. Marston v. People, (Colo. No. 20SC695, Jan. 11,
2021) (unpublished order). In Linnebur, the supreme court held
that the requirement of three or more prior qualifying offenses is an
element of felony DWAI that must be found by a jury beyond a
reasonable doubt. Linnebur, ¶¶ 2, 31. Following Linnebur, we
reverse Marston’s conviction for felony DWAI and remand for
further proceedings consistent with this opinion. We once again
address Marston’s other contentions, however, because they bear
on whether a conviction for misdemeanor DWAI can stand and
would arise in the event of any retrial for felony DWAI.
I. Background
¶3 Shortly before noon one day, J.P. was driving behind a red
truck when he saw the truck straddling lanes and speeding up and
slowing down erratically. He also saw the driver nodding off at the
wheel. J.P. called 911 and followed the truck to a 7-Eleven.
Marston got out of the truck and went into the 7-Eleven, at which
point J.P. approached a Jefferson County Sheriff’s deputy —
Deputy Aaron Fosler — who had just pulled into the parking lot.
2
J.P. told Deputy Fosler what he had seen. Deputy Fosler followed
Marston into the 7-Eleven.
¶4 Deputy Fosler asked Marston to step outside the convenience
store and answer some questions. Marston obliged. As Deputy
Fosler held the door open and Marston walked out, he saw that
Marston was “staggering, grabbing something to hold onto.”
Outside, Deputy Fosler questioned Marston about his driving and
whether he had been drinking. Marston told him that his driver’s
license was suspended, told the officer he had driven to the
7-Eleven but then said his girlfriend had driven him there, and told
the officer he had downed several “mixed drinks” the night before at
his girlfriend’s house. Unprompted, Marston asked Deputy Fosler if
there was any way to keep his truck from being towed if he was
taken to jail. Throughout this conversation, Deputy Fosler noticed
that Marston’s eyes were red and watery, he smelled of alcohol, and
his speech was “thick tongued.”1
1 Sometime during this conversation, a second deputy arrived and,
for part of the time, stood nearby. That officer also noticed
Marston’s signs of intoxication.
3
¶5 Based on Marston’s statements and Deputy Fosler’s
observations, Deputy Fosler called for another officer, Deputy Kevin
Kehl, to administer roadside field sobriety tests. Kehl did so. One
such test was the HGN test. As discussed more fully below, that
test requires the subject to follow an object (for example, a pen) with
his eyes to the left and right. The person administering the test
must watch the subject’s eyes to detect any involuntary “jerking” of
his eyeballs.
¶6 At one point during the roadside tests, when Deputy Kehl was
demonstrating a walk-and-turn maneuver, Marston said, “I couldn’t
do that sober.” Deputy Kehl determined that Marston didn’t
perform as a sober person would on the HGN test and the other
roadside tests and arrested him. Marston refused to take a
chemical test.
¶7 After Marston’s girlfriend picked up the truck from the
7-Eleven, she found bottles of vodka in the back of the truck. She
testified at trial that, contrary to what Marston had told Deputy
Fosler, she wasn’t with Marston the night before the arrest and in
fact hadn’t seen him in several weeks.
4
¶8 The People charged Marston with driving under the influence
(DUI) and driving under restraint. Marston went to trial on the DUI
charge. The jury ultimately convicted him of the lesser included
DWAI offense. The court then determined that Marston had at least
three prior alcohol-related driving convictions and sentenced him
for felony DWAI. See § 42-4-1301(1)(b), C.R.S. 2020.
II. Discussion
¶9 Marston contends that the district court erred by (1)
determining that he had three prior alcohol-related driving
convictions by a preponderance of the evidence rather than having
the jury determine those convictions as elements that must be
proven beyond a reasonable doubt; (2) denying his motion to
suppress his statements to Deputy Fosler at the scene; and (3)
denying his request for a Shreck hearing on (a) the reliability of the
HGN test and (b) Deputy Kehl’s expertise. We address each
contention in turn.
A. Prior Convictions
¶ 10 Marston contends that the district court erred by finding that
he had at least three prior alcohol-related driving convictions by a
preponderance of the evidence rather than submitting the issue to
5
the jury for it to decide beyond a reasonable doubt. He argues that
the prior convictions are elements of the crime. As noted, Linnebur
so holds. And it requires that we reverse Marston’s DWAI
conviction. On remand, the People may elect to retry Marston on
the felony charge, and if Marston raises a double jeopardy objection
the district court should address it. Linnebur, ¶ 32. If the People
choose not to retry Marston on the felony charge, the district court
should, given our rejection below of Marston’s other contentions of
error, enter a conviction for misdemeanor DWAI. Id.
B. Marston’s Statements to Police
¶ 11 Marston next contends that his statements to Deputy Fosler at
the scene should have been suppressed because they were
involuntary.2 If Marston is correct, any conviction for DWAI would
be thrown into doubt. And the issue may arise on remand.
Therefore, we address it.
2Marston’s motion didn’t specify what statements he wanted
suppressed. At the suppression hearing, Marston’s attorney said
she was challenging “everything at the scene.” But on appeal,
Marston only challenges the voluntariness of his statements to
Deputy Fosler.
6
1. Standard of Review
¶ 12 “A trial court’s suppression ruling presents a mixed question
of fact and law.” People v. Ramadon, 2013 CO 68, ¶ 21. We won’t
overturn the trial court’s factual findings if they are supported by
competent evidence in the record; however, we review the legal
effect of those facts de novo. Id.; Effland v. People, 240 P.3d 868,
878 (Colo. 2010) (“[T]he ultimate determination of whether a
statement is voluntary is a legal question and is reviewed de novo.”).
And we review any error under the constitutional harmless error
standard; that is, we reverse unless the People show that the error
was harmless beyond a reasonable doubt. Hagos v. People, 2012
CO 63, ¶ 11.
2. Applicable Law
¶ 13 “[A] defendant’s statements must be voluntary to be
admissible as evidence.” Ramadon, ¶ 18. In determining whether a
defendant’s statements were voluntary, we “must consider the
totality of the circumstances ‘to determine whether the accused’s
will was actually overborne by coercive police conduct.’” People v.
Coke, 2020 CO 28, ¶ 18 (quoting Sanchez v. People, 2014 CO 56,
¶ 11). To do so, we engage in a two-step inquiry: we first look to
7
whether the police conduct was coercive; if so, we then look to
whether that conduct “played a significant role in inducing the
statements.” Ramadon, ¶ 20. The statements “must not be the
product of any direct or implied promises, nor obtained by exerting
an improper influence.” People v. Medina, 25 P.3d 1216, 1222
(Colo. 2001).
¶ 14 To determine whether the police conduct was coercive, we may
consider, among other things, the following factors:
(1) whether the defendant was in custody;
(2) whether the defendant was free to leave;
(3) whether the defendant was aware of the
situation;
(4) whether the police read Miranda rights to
the defendant;
(5) whether the defendant understood and
waived Miranda rights;
(6) whether the defendant had an opportunity
to confer with counsel or anyone else prior
to or during the interrogation;
(7) whether the statement was made during
the interrogation or volunteered later;
(8) whether the police threatened [the]
defendant or promised anything directly or
impliedly;
(9) the method or style of the interrogation;
(10) the defendant’s mental and physical
condition just prior to the interrogation;
(11) the length of the interrogation;
(12) the location of the interrogation; and
(13) the physical conditions of the location
where the interrogation occurred.
8
Ramadon, ¶ 20 (quoting Medina, 25 P.3d at 1222-23).
3. Analysis
¶ 15 We agree with the district court’s determination that Marston’s
will wasn’t overborne by coercive police conduct and that his
statements were therefore voluntary. The following facts, almost all
of which are undisputed, lead us to this conclusion:
 Deputy Fosler asked Marston if he wouldn’t mind
stepping outside and answering some questions; he
didn’t order him to do so. Marston agreed.
 No officer made any threats or promises to Marston.
 The encounter occurred outside, in a public place.
 Marston seemed be aware of the situation. (He had been
in this situation several times before.) For example,
unprompted, he asked if there was any way he could
prevent his truck from being towed if he was taken to jail.
 Marston appeared to understand Deputy Fosler’s
questions and gave responsive answers.
 Marston wasn’t restrained in any way and hadn’t yet
been taken into custody.
 Deputy Fosler used a conversational tone.
9
 The deputies didn’t use any subtle psychological
pressure to get Marston to talk.
¶ 16 Marston asserts that his statements were coerced because
more than one deputy was present, the two deputies stood close to
him, the encounter lasted twenty to thirty minutes, he wasn’t given
a Miranda advisement, and he wasn’t free to leave. But looking at
the totality of the circumstances, as we must, see Coke, ¶ 18, we
conclude that these facts don’t add up to coercion.
¶ 17 People v. Zadran, 2013 CO 69M, presents an instructive
comparison. In that case, the supreme court determined that the
police officer’s statements to the defendant — “I think it would be in
your best interest to talk to me,” “I think you are going to be
interested in some of the things that I already know,” “It is what it
is. You messed up. You know you messed up,” and “You want to
get ahead of this. You want to make things right. You want a
positive outcome from this. I’m trying to do the [least] invasive
thing that I can do here” — didn’t show police coercion. And this
even though the defendant was in custody and wasn’t free to leave.
Id. at ¶¶ 15-19. The court contrasted the facts before it with those
10
in cases in which the police exploited a defendant’s “particular set
of vulnerabilities.” Id. at ¶¶ 17-18.
¶ 18 In terms of showing coercion, the facts of this case don’t even
approach those in Zadran, in which the court found no coercion.
Deputy Fosler simply asked Marston, in a conversational tone,
questions about his driving and alcohol consumption. We see no
indication that Marston’s will was overborne by coercive police
conduct.
C. Denial of a Shreck Hearing
¶ 19 Next, Marston contends that the district court erred by
refusing to hold a Shreck hearing on the science, reliability, and
margin of error of the HGN test, as well as Deputy Kehl’s expertise
on those issues. We address this issue for the same reasons we
address Marston’s contention that his statements to the police
weren’t admissible. We conclude that the district court didn’t err by
denying Marston a hearing, but that even if it did, any error was
harmless.
1. The District Court’s Ruling
¶ 20 After the prosecution endorsed Deputy Kehl as an expert in
HGN testing, Marston filed a motion requesting a Shreck hearing to
11
challenge the admissibility of the HGN test and Deputy Kehl’s
qualifications as an expert. In response, the prosecution argued
that a hearing wasn’t necessary, citing district court cases from
Colorado and appellate court cases from other jurisdictions in
which HGN testing had been found “reasonably reliable” and
accepted by the scientific community. At a motions hearing, the
district court heard argument from both sides as to why a Shreck
hearing was or wasn’t necessary. It ultimately found that “the
scientific community has accepted over many years the fact that the
HGN is a reliable and relevant tool to help police officers determine
if someone is under the influence of alcohol,” and concluded that
the science was reliable and that if the prosecution properly
qualified Deputy Kehl as an expert, his testimony would be useful
to the jury.
2. Standard of Review
¶ 21 We review a district court’s denial of a request for a Shreck
hearing for an abuse of discretion. See People v. Rector, 248 P.3d
1196, 1201 (Colo. 2011) (“Once a party requests a Shreck analysis,
a trial court is vested with the discretion to decide whether an
evidentiary hearing would aid the court in its Shreck analysis.”). “A
12
trial court abuses its discretion only if its decision is manifestly
arbitrary, unreasonable, [or] unfair, or is based on a
misunderstanding or misapplication of the law.” People v.
Thompson, 2017 COA 5, ¶ 91. And “we review any error in denying
a Shreck hearing under the nonconstitutional harmless error
standard.” People v. Wilson, 2013 COA 75, ¶ 24; cf. Campbell v.
People, 2019 CO 66, ¶ 34 (error in allowing officer to testify as a lay
witness regarding HGN reviewed for nonconstitutional harmless
error). We therefore reverse only if any error substantially
influenced the verdict or impaired the fairness of the trial. Wilson,
¶ 24.
3. Analysis
¶ 22 To decide whether the district court abused its discretion by
allowing Deputy Kehl to testify about Marston’s performance on the
HGN test without first holding a Shreck hearing, we proceed in the
following steps. First, we discuss the nature of the test and its use
in Colorado courts. Second, we discuss Shreck’s admissibility
framework. Third, we assess whether there is sufficient indication
that the HGN test satisfies Shreck’s admissibility test, or whether a
Shreck hearing was required.
13
a. The HGN Test
¶ 23 The HGN test measures the subject’s ability to maintain visual
fixation on an object as his eyes move from side to side. Nat’l
Traffic L. Ctr., Am. Prosecutors Rsch. Inst., Horizontal Gaze
Nystagmus: The Science and the Law (n.d.),
https://perma.cc/UW93-GHPD. (“Nystagmus” is a rapid,
involuntary oscillation of the eyeballs.) An officer holds an object (a
pen, small flashlight, or finger) about twelve to fifteen inches in
front of a subject’s nose. The officer asks the subject to remove any
glasses, to stand still with his feet together and hands at his sides,
and to focus on the object. The officer then moves the object slowly
back and forth horizontally three times, observing whether each of
the subject’s eyes smoothly tracks the object. Continuing Legal
Education in Colorado, Inc., Colorado DUI Benchbook § 6.2.2
(2019-2020 ed.); see also Am. Prosecutors Rsch. Inst., Admissibility
of Horizontal Gaze Nystagmus Evidence 5 (2003),
https://perma.cc/R36W-CCXR. The officer looks for three testing
points for each eye (six total): lack of smooth pursuit, distinct
jerking of the eyes at maximum deviation, and jerking that occurs
before a forty-five-degree angle. Nat’l Highway Traffic Safety
14
Admin., DWI Detection and Standardized Field Sobriety Test (SFST)
Participant Manual Session 7, page 9 of 39 (rev. Feb. 2018),
https://perma.cc/4R6E-ZB3A; see State v. Baue, 607 N.W.2d 191,
201-02 (Neb. 2000) (describing the test). If four or more of these
clues are present, the subject’s blood alcohol content (BAC) is likely
at or above 0.08%. DWI Detection at Session 8, page 37 of 95;
Baue, 607 N.W.2d at 202.
¶ 24 The National Highway Traffic Safety Administration (NHTSA)
standardized the HGN test along with the walk-and-turn and
one-leg-stand tests in 1981, finding that, combined, the tests can
accurately determine whether a subject’s BAC is .10 or higher
eighty-three percent of the time. Horizontal Gaze Nystagmus: The
Science and the Law. Those tests are now the standard field
sobriety tests in use across the country.
¶ 25 In Colorado, “virtually every judge now takes judicial notice of
the scientific principles underlying HGN testing,” though Colorado’s
appellate courts haven’t yet addressed the test’s admissibility.
Colorado DUI Benchbook § 6.2.2.
15
b. Shreck
¶ 26 In Shreck, the Colorado Supreme Court adopted a “liberal,”
“totality of the circumstances” test, grounded in relevant rules of
evidence, for determining whether scientific evidence is admissible
through expert testimony. To get there, the court first rejected the
so-called Frye test (derived from Frye v. United States, 293 F. 1013
(D.C. Cir. 1923)), which Colorado appellate courts had applied,
albeit perhaps inconsistently, for several decades. The Frye test
requires that a scientific conclusion gain “general acceptance in the
particular field to which it belongs” as to both the underlying theory
supporting the conclusion and the techniques and experiments
employing it, before evidence based on that conclusion can be
introduced in court. Shreck, 22 P.3d at 73 (quoting Frye, 293 F. at
1014). The court determined that the Frye test is too rigid and is
inconsistent with the more flexible approach countenanced by the
Colorado Rules of Evidence. Id. at 76-77.
¶ 27 The Shreck court also discussed the United States Supreme
Court’s decision in Daubert v. Merrell Dow Pharmaceuticals, Inc.,
509 U.S. 579 (1993), which likewise rejected Frye, holding that its
“rigid general acceptance requirement [is] at odds with the ‘liberal
16
thrust’ of the Federal Rules [of Evidence] and their ‘general
approach of relaxing the traditional barriers to opinion testimony.’”
Id. at 588 (quoting Beech Aircraft Corp. v. Rainey, 488 U.S. 153, 169
(1988)). Rather than adopting the Daubert approach wholesale,
however, the Colorado Supreme Court went its own way.
¶ 28 Ultimately, the court adopted a rubric supported by CRE 403
and 702 “because their flexibility is consistent with a liberal
approach that considers a wide range of issues.” Shreck, 22 P.3d at
77. An admissibility analysis under Shreck requires the court to
determine whether “(1) the scientific principles underlying the
testimony are reasonably reliable; (2) the expert is qualified to opine
on such matters; (3) the expert testimony will be helpful to the jury;
and (4) the evidence satisfies CRE 403.” Rector, 248 P.3d at 1200;
see Shreck, 22 P.3d at 77-79. In making these determinations, the
court can consider a broad range of indicia “that may be pertinent
to the evidence at issue.” Shreck, 22 P.3d at 77. These may
include, but certainly aren’t limited to, the factors identified in
Daubert. Id. at 77-78.
¶ 29 Before applying the Shreck framework to the testimony at
issue in this case, we pause to address Marston’s assertion that
17
Shreck “is widely regarded as imposing a more rigorous ‘gatekeeper’
function on trial courts than Frye did.” (The point matters because,
as discussed below, some courts have applied the Frye test in
determining HGN test admissibility, and so understanding the
relative restrictiveness of the tests will prove informative.) To the
extent Marston intends to suggest that the Shreck test is more
limiting than the Frye test, he is wrong, for at least two reasons.
¶ 30 First, Marston’s assertion is based on a quote from an Alaska
Supreme Court case, State v. Coon, 974 P.2d 386, 390 (Alaska
1999), abrogated by State v. Sharpe, 435 P.3d 887 (Alaska 2019),
that is taken out of context. That case compared the Daubert test
(not the Shreck test, which the Colorado Supreme Court adopted
two years later) to the Frye test. And in saying that the Daubert test
imposes a more rigorous gatekeeper function, the Alaska court
merely observed that, under Daubert, admissibility depends on
consideration of several factors, while Frye gives dispositive weight
to but one — general acceptance.
¶ 31 Second, Shreck itself repeatedly contrasts Frye’s “rigid”
(indeed, too rigid) approach to the more “liberal” approach
contemplated by the Colorado Rules of Evidence. See Shreck, 22
18
P.3d at 76 (rejecting Frye because it “restricts the admissibility of
reliable evidence that may not yet qualify as ‘generally accepted’”)
(citation omitted).3 And the court emphasized that “[a]ny concerns
that invalid scientific assertions will be admitted under this liberal
standard are assuaged by Rule 702’s overarching mandate of
reliability and relevance. . . . Such concerns are also mitigated by
‘[v]igorous cross-examination, presentation of contrary evidence,
and careful instruction on the burden of proof.’” Id. at 78 (quoting
Daubert, 509 U.S. at 596).
c. Application
i. HGN Test Evidence is Generally Admissible
¶ 32 A number of relevant considerations identified in Shreck
support the admissibility of HGN test results as evidence of
impairment:
1. The technique has been tested and subjected to peer
review and publication. See State v. Ruthardt, 680 A.2d
3Indeed, the court in Shreck concluded that certain scientific
evidence that may not have been generally accepted was
nonetheless admissible. People v. Shreck, 22 P.3d 68, 80-81 (Colo.
2001).
19
349, 357 (Del. Super. Ct. 1996) (citing some of the
relevant literature); State v. Dahood, 814 A.2d 159, 166
(N.H. 2002) (recognizing “extensive scientific literature
dating back to the 1950s that thoroughly examines and
critiques the HGN test and the theory underlying that
test-that there is a strong correlation between the
amount of alcohol a person consumes and the onset of
nystagmus”); see, e.g., Marcelline Burns & Ellen W.
Anderson, Nat’l Highway Traffic Safety Admin., A
Colorado Validation Study of the Standardized Field
Sobriety Test (SFST) Battery (Nov. 1995),
https://perma.cc/5MMA-NR8W; Gregory W. Good & Arol
R. Augsburger, Use of Horizontal Gaze Nystagmus as a
Part of Roadside Sobriety Testing, 63 Am. J. Optometry &
Physiological Optics 467 (1986); V. Tharp, M. Burns & H.
Moskowitz, Nat’l Highway Traffic Safety Admin.,
Development and Field Test of Psychophysical Tests for
DWI Arrest (Mar. 1981), https://perma.cc/5HA3-S3KV.
2. Studies have produced reliability rates indicating a
significant correlation between test results and
20
impairment. See, e.g., Horizontal Gaze Nystagmus: The
Science and the Law (combined, the HGN test, the
walk-and-turn test, and the one-leg-stand test accurately
determine whether a subject’s BAC was .10 or higher
eighty-three percent of the time); Jack Stuster &
Marcelline Burns, Validation of the Standardized Field
Sobriety Test Battery at BACs Below .10 Percent (Aug.
1998), https://perma.cc/E5BL-PGFH (study showed that
the HGN test could often accurately predict whether a
subject’s BAC is at or above 0.08).
3. Standards have been developed to ensure consistency in
the application of the test and the assessment of
responses. See DWI Detection and Standardized Field
Sobriety Test (SFST) Participant Manual at Session 4, page
35 of 36, Session 7, pages 8-11 of 39 (providing
instructions for application and evaluation of the HGN
test nationwide).
4. There is substantial specialized literature dealing with
the technique. See Dahood, 814 A.2d at 166 (reviewing
some of the literature); see, e.g., Stephanie E. Busloff,
21
Comment, Can Your Eyes Be Used Against You — The
Use of the Horizontal Gaze Nystagmus Test in the
Courtroom, 84 J. Crim. L. & Criminology 203 (Spring
1993).
5. The evidence has been offered in many other cases in
Colorado as evidence of alcohol impairment. See, e.g.,
Campbell, ¶¶ 7, 13-15 (HGN test results admitted at
trial); People v. Haack, 2019 CO 52, ¶¶ 1, 8 (trial court
found that HGN test results would have been admissible
but for an unrelated constitutional violation).4
See Shreck, 22 P.3d at 77-78 (identifying these considerations as
relevant).
¶ 33 As well, a survey of case law from other jurisdictions shows
that most allow evidence of HGN test results as evidence of
impairment. Some of these decisions employ a Daubert- or
Shreck-like analysis, but some employ the even more restrictive
4 As noted above, the prosecution cited several trial court decisions
admitting evidence of HGN test results in responding to Marston’s
motion for a Shreck hearing. Marston has never disputed the point
that Colorado trial courts regularly admit such evidence.
22
Frye test. See, e.g., Ballard v. State, 955 P.2d 931, 940 (Alaska Ct.
App. 1998) (HGN evidence meets Frye test if results are offered to
show a person has consumed alcohol and is potentially impaired),
overruled on other grounds as recognized by Alvarez v. State, 249
P.3d 286 (Alaska 2011); State ex rel. Hamilton v. City Ct., 799 P.2d
855, 859 (Ariz. 1990) (HGN test satisfies the Frye standard if offered
only as evidence of impairment); State v. Commins, 850 A.2d 1074,
1080-81 (Conn. App. Ct. 2004) (HGN test evidence satisfied Daubert
test), aff’d on other grounds, 886 A.2d 824 (Conn. 2005); Ruthardt,
680 A.2d at 356-60 (applying Shreck-like test; HGN test results
admissible as evidence of impairment); Williams v. State, 710 So. 2d
24, 30-32 (Fla. Dist. Ct. App. 1998) (the HGN test is a reliable
indicator of the presence of alcohol in blood, and there is no need
for trial courts to reapply a Frye analysis to HGN); Hawkins v. State,
476 S.E.2d 803, 806-08 (Ga. Ct. App. 1996) (HGN test results
admissible without expert testimony regarding the scientific validity
of the test; applying a Shreck-like totality of the circumstances test);
State v. Gleason, 844 P.2d 691, 694-95 (Idaho 1992) (HGN
testimony admissible under Frye test as evidence of impairment);
State v. Taylor, 694 A.2d 907, 911-12 (Me. 1997) (applying Frye
23
test; HGN test results admissible as evidence of impairment);
Schultz v. State, 664 A.2d 60, 69-70 (Md. Ct. Spec. App. 1995)
(courts may take judicial notice of the results of an HGN test); State
v. Klawitter, 518 N.W.2d 577, 584-86 (Minn. 1994) (HGN test
results satisfied Frye test); State v. Hill, 865 S.W.2d 702, 703-04
(Mo. Ct. App. 1993) (HGN test satisfies Frye test if offered as
evidence of intoxication), overruled on other grounds by State v.
Carson, 941 S.W.2d 518 (Mo. 1997); Baue, 607 N.W.2d at 201-04
(HGN test results admissible as evidence of impairment under Frye
test); Dahood, 814 A.2d at 166-67 (HGN test results admissible
under Daubert test); State v. Aleman, 194 P.3d 110, 115-16 (N.M.
Ct. App. 2008) (HGN test results admissible under Daubert test);
City of Fargo v. McLaughlin, 512 N.W.2d 700, 703-08 (N.D. 1994)
(HGN test results admissible under Frye test if offered in
conjunction with other field sobriety tests); State v. O’Key, 899 P.2d
663, 689 (Or. 1995) (HGN test results admissible under Daubert
test); Emerson v. State, 880 S.W.2d 759, 763-69 (Tex. Crim. App.
1994) (HGN test results admissible under Texas Rule of Criminal
Evidence 702; applying Daubert-like test); see also United States v.
Horn, 185 F. Supp. 2d 530, 561 (D. Md. 2002) (collecting cases).
24
¶ 34 Marston cites a few cases rejecting the admissibility of HGN
test results under the facts before them. Ex parte Malone, 575 So.
2d 106 (Ala. 1990); State v. Meador, 674 So. 2d 826 (Fla. Dist. Ct.
App. 1996); People v. McKown, 875 N.E.2d 1029 (Ill. 2007); State v.
Witte, 836 P.2d 1110 (Kan. 1992); State v. Lasworth, 42 P.3d 844
(N.M. Ct. App. 2001); Commonwealth v. Apollo, 603 A.2d 1023 (Pa.
Super. Ct. 1992).5 But those cases usually apply the Frye test,
which, as discussed above, is more restrictive than the “liberal”
Shreck test. And even then, they don’t reject such evidence
outright, but hold that the evidence before them wasn’t sufficient to
establish reliability and leave open the possibility that such
evidence could be presented. See also Commonwealth v. Sands,
675 N.E.2d 370, 371-73 (Mass. 1997) (trial court erred by allowing
officer to testify about HGN test results without being qualified as
an expert, but indicating that HGN test results would be admissible
if supported by expert testimony from the person administering the
5Marston also cites State v. Superior Court, 718 P.2d 171 (Ariz.
1986), in support of his position. But the court in that case
actually held that HGN test results are admissible as evidence of
impairment (but not as evidence of a specific BAC level). Id. at 182.
25
 test); State v. Helms, 504 S.E.2d 293, 294-96 (N.C. 1998) (same);
State v. Murphy, 953 S.W.2d 200, 202-03 (Tenn. 1997) (same); State
v. Cissne, 865 P.2d 564, 566-69 (Wash. Ct. App. 1994) (same).6
¶ 35 The weight of judicial authority therefore favors admissibility
of HGN test results without the need for additional evidence of
scientific reliability — at least if the evidence is offered only as
evidence of impairment and not a specific BAC level.7
¶ 36 We recognize that there isn’t unanimous agreement among
academics and other commentators concerning the reliability of the
HGN test. But much of the disagreement doesn’t relate to whether
alcohol can cause nystagmus — that point is widely accepted.
Rather, some have noted that there can be reasons other than
6 In at least one instance, the court reversed course after additional
evidence of reliability was presented. State v. Aleman, 194 P.3d
110, 115-16 (N.M. Ct. App. 2008) (backtracking on its earlier
holding in State v. Lasworth, 42 P.3d 844 (N.M. Ct. App. 2001)).
7 A few courts have held that this type of evidence isn’t scientific
evidence at all, and therefore isn’t subject to restrictions on
scientific evidence. State v. Murphy, 451 N.W.2d 154, 156-58 (Iowa
1990); State v. Nagel, 506 N.E.2d 285, 286 (Ohio Ct. App. 1986);
Salt Lake City v. Garcia, 912 P.2d 997, 1000-01 (Utah Ct. App.
1996). We align ourselves, however, with the vast majority of courts
that have held that such evidence is based, at least in part, on
scientific principles.
26
alcohol impairment that may explain test results in a particular
case, see, e.g., William A. Pangman, Horizontal Gaze Nystagmus:
Voodoo Science, 2 DWI J. 1, 2 (1987), or that police officers may not
be sufficiently trained in administering the test. And some claim a
higher incidence of false positives than reported by NHTSA and
other studies. Busloff, 84 J. Crim. L. & Criminology at 211 (noting
that NHTSA’s “experimental procedure has been further challenged
for its intentional screening out of those individuals highly likely to
be misclassified as false positives”). We believe such concerns go to
the weight of the evidence, not its admissibility. See Ruthardt, 680
A.2d at 359-60 (so holding); Dahood, 814 A.2d at 166-67 (same).
They can be addressed through the presentation of evidence by the
defense, cross-examination, and rigorous application of the rules
governing an expert’s qualifications. See Daubert, 509 U.S. at 596
(“Vigorous cross-examination, presentation of contrary evidence,
and careful instruction on the burden of proof are the traditional
and appropriate means of attacking shaky but admissible
evidence.”); Shreck, 22 P.3d at 78 (same).
¶ 37 We therefore conclude that evidence of HGN test results is
admissible as evidence of impairment if offered through a qualified
27
expert witness. Contrary to Marston’s assertion, such an expert
doesn’t have to be an expert in the science underlying the test. It is
enough that the witness is an expert in administering the test and
interpreting the subject’s responses. See, e.g., Ballard, 955 P.2d at
942 (trooper could testify about the results of the HGN test because
the court could find he was qualified to administer the test and
assess the results); People v. Leahy, 882 P.2d 321, 336 (Cal. 1994)
(once HGN testing is shown to be generally accepted, officers may
be deemed qualified to testify as to test results and the prosecution
won’t be required to submit expert testimony confirming a police
officer’s evaluation of an HGN test); Taylor, 694 A.2d at 912 (“A
proper foundation shall consist of evidence that the officer or
administrator of the HGN test is trained in the procedure and the
test was properly administered.”); State v. Torres, 976 P.2d 20,
34-35 (N.M. 1999) (the expert is qualified to testify if it is shown
that he had ability and training to administer the HGN test
properly, and that he did in fact administer the test properly); see
also Campbell, ¶¶ 26-31 (officer testifying as to HGN test results
must be qualified as an expert in administration and interpretation
of the test).
28
¶ 38 Though a party may request a Shreck hearing on the
admissibility of the proposed testimony, a trial court isn’t required
to grant that request if it has “sufficient information to make
specific findings under CRE 403 and CRE 702 about the reliability
of the scientific principles involved, the expert’s qualification to
testify to such matters, the helpfulness to the jury, and potential
prejudice.” Rector, 248 P.3d at 1201. The district court in this case
had ample information before it from which it could determine the
admissibility of the HGN test results without granting Marston’s
request for a Shreck hearing. And Deputy Kehl was sufficiently
qualified to testify about the administration and interpretation of
the test. (Marston doesn’t contest this point.) Though the court
didn’t make extensive findings, it didn’t abuse its discretion.
ii. Alternatively, Any Error Was Harmless
¶ 39 Even if the district court did err, we agree with the People that
any error was harmless.
¶ 40 In Campbell, the supreme court determined that while the
district court erred by allowing a police officer to testify about the
results of an HGN test without being qualified as an expert, the
error was harmless. Campbell, ¶¶ 1-2, 35. The court discussed the
29
“overwhelming” evidence against Campbell aside from the HGN test,
including the following:
 “Campbell’s breath had an odor of alcohol.”
 “[H]is eyes were bloodshot.”
 “[H]is speech was slurred.”
 He was uncoordinated: “he dropped his wallet while
trying to retrieve his identification,” and, “when Campbell
tried to get out of his truck, the officer saw him reach for
the door handle twice without success before grabbing it
and opening the door.”
 Bottles of alcohol were found in his car.
 He failed two of the other field sobriety tests.
 He had admitted to consuming alcohol.
 He took two breath tests, which showed BAC levels of
0.07 and 0.086, respectively.
Id. at ¶¶ 36-40.
¶ 41 There is similar overwhelming evidence against Marston:
 Two of the three officers reported that Marston’s breath
smelled like alcohol.
30
 All three observed that he had bloodshot eyes.
 Two of the three noticed that his speech was slurred.
 Marston had trouble keeping his balance as he walked
out of the 7-Eleven into the parking lot, and two of the
three officers reported that he had to reach to keep his
balance.
 Bottles of alcohol were found in the truck.
 Marston didn’t complete the other two field sobriety tests
as a sober person would. Deputy Kehl observed three of
eight clues on the walk-and-turn test. On the
one-leg-stand test, Marston could only lift his leg for
approximately four seconds.
 Marston admitted to drinking alcohol the night before.
¶ 42 Unlike Campbell, Marston didn’t submit to a breath test. (Nor
did he submit to a blood test.) But a witness saw him driving
erratically and nodding off at the wheel. And Marston said, “I
couldn’t do that sober,” when Deputy Kehl demonstrated the
walk-and-turn maneuver.
¶ 43 Because of the overwhelming amount of evidence against
Marston independent of the HGN test results, we conclude that any
31
error in allowing Deputy Kehl to testify about those results without
first holding a Shreck hearing didn’t substantially influence the
verdict or impair the fairness of the trial. See Hagos, ¶ 12; Wilson,
¶ 24.
III. Conclusion
¶ 44 The judgment is reversed, and the case is remanded for
proceedings consistent with this opinion.
JUDGE WELLING and JUDGE GOMEZ concur.
32