Paso County District Court No. 13CR2453 Honorable Michael P.
J. Weiser, Attorney General, Charlotte M. Powers, Assistant
Attorney General, Denver, Colorado, for Plaintiff-Appellee
A. Ring, Colorado State Public Defender, Tracy C. Renner,
Deputy State Public Defender, Denver, Colorado, for
J., concurs Román, J., concurs in part and dissents in
Introduction and Summary
1 The principal issue in this appeal of a criminal
prosecution for menacing, assault, harassment, and cruelty to
an animal, is the propriety of the admission of
"blind" expert testimony regarding the dynamics of
abusive intimate relationships.
2 A "blind" or "cold" expert knows little
or nothing about the facts of a particular case, often has
not met the victim, and has not performed any forensic or
psychological examination of the victim (or the defendant).
See Fed. R. Evid. 702 advisory committee's note
to 2000 amendments; see also Christopher Tarver
Robertson, Blind Expertise, 85 N.Y.U.L. Rev. 174
3 Colorado courts repeatedly have recognized the value of
blind expert testimony in appropriate cases. Venalonzo v.
People, 2017 CO 9, ¶¶ 32-34; People v.
Wittrein, 221 P.3d 1076, 1081 (Colo. 2009); People
v. Relaford, 2016 COA 99, ¶¶ 26-30; see
also People v. Fortson, 2018 COA 46M (Berger, J.,
specially concurring). When the actions of a victim are
counterintuitive to what an ordinary juror might expect, this
type of expert testimony may be crucial in explaining to the
jury what social science has learned about the behavior
patterns of people who are involved in violent relationships.
Venalonzo, ¶¶ 32-34. Without this
testimony, jurors may well reach incorrect decisions because
they do not have the background to understand such
counterintuitive actions. Relaford, ¶ 30.
Nothing in this opinion questions the admissibility of such
testimony in the proper case.
4 But, there are substantial risks attendant to the admission
of blind expert testimony that cannot be ignored. When blind
expert testimony is used to persuade the jury to make
findings of historical fact that are not supported by
evidence presented to the jury, the trial process is
corrupted, and the defendant may, as a result, be deprived of
a fair trial.
5 We conclude that virtually all of the blind expert
testimony presented in this case was wholly irrelevant to the
issues properly before the jury. We further conclude that the
admission of this evidence was highly prejudicial.
Accordingly, we reverse the convictions and remand for a new
Facts and Procedural History
6 Kerry Lee Cooper and L.K. were in an intimate relationship
and living together at the time of the alleged assault. In
the early hours of a morning in the summer of 2013, L.K. woke
up in a panic attack. She felt like she could not breathe. It
was very hot in the room, so L.K. asked Cooper to plug in the
nearby fan. Cooper turned on the fan and placed it on the
floor. L.K. was unhappy with the positioning of the fan and
the two began to argue.
7 According to L.K.'s testimony, Cooper then shoved the
running fan into L.K.'s face, cutting her face with the
grabbed a flashlight from the nightstand and hit Cooper on
the head with it. Cooper dropped the fan and began hitting
L.K. in the face and ribs with his closed fist. L.K. crawled
to the window and screamed for help. Cooper told L.K. to shut
up and grabbed her by the jaw, inserting his fingers into her
mouth. She bit one or more of his fingers. Cooper then
grabbed a tire iron located just outside the bedroom and told
L.K. to stop screaming or he would hit her with it. When she
did not, he hit her twice with the tire iron.
8 Cooper testified that he did not punch L.K., grab her jaw,
or pick up the tire iron and hit L.K. with it. According to
him, L.K. asked him to reposition the fan, and, when she
became unhappy with the way he had positioned it, he threw
the fan on the end of the bed, at which point L.K. hit him
with the flashlight and bit his hand when he attempted to
take the flashlight away from her to protect
Cooper did not deny, however, that he pushed L.K in her
9 Cooper's daughter, who lived close by, heard the
screaming and called the police. Officers obtained statements
from Cooper and L.K. and observed injuries on both of them.
10 At trial, over Cooper's repeated objections, the
prosecution presented extensive testimony from an expert
witness about (1) characteristics of domestic violence
relationships; and (2) the "power and control
wheel," a tool developed purportedly to explain the ways
an abusive partner can use power and control to manipulate a
11 The jury acquitted Cooper of the menacing and cruelty to
animal charges but convicted him of third degree assault and
12 On appeal, Cooper asserts that (1) the trial court erred
in admitting the blind expert witness testimony both on
reliability and relevance grounds; (2) the prosecutor engaged
in prosecutorial misconduct during closing argument; and (3)
the court committed plain error when it did not give a
special unanimity instruction on the assault charge.
13 We agree that the expert testimony was inadmissible
because it was irrelevant and highly prejudicial; therefore,
we reverse the convictions and remand for a new trial. To
provide guidance on remand, we reject Cooper's claim that
he was entitled to a modified unanimity instruction. We
decline to address the alleged claims of prosecutorial
misconduct because we do not know whether those statements
will recur at the retrial.
Vast Bulk of the Blind Expert Testimony Was
14 Only relevant evidence is admissible. CRE 402. Irrelevant
evidence is not admissible. Id. The question here is
whether expert opinions regarding domestic violence had any
relevance or "fit" to the facts that were presented
to the jury at trial.
15 To illustrate our analysis, the chart that appears in the
Appendix catalogues each opinion expressed by the expert
witness and the historical evidence, if any, presented to the
jury that had any relationship to the expressed opinion.
Standard of Review
16 We review a trial court's evidentiary ruling for an
abuse of discretion. People v. Welsh, 80 P.3d 296,
304 (Colo. 2003). A trial court abuses its discretion if its
ruling is manifestly arbitrary, unreasonable, or unfair,
id., or if it misconstrues or misapplies the law,
People v. Glover, 2015 COA 16, ¶ 10.
Admissibility of Expert Testimony
17 CRE 702 governs the admission of expert testimony.
Exercising its gatekeeper function, the trial court must
"focus on the reliability and relevance of the proffered
evidence" and determine "(1) the reliability of the
scientific principles, (2) the qualifications of the witness,
. . . (3) the usefulness of the testimony to the jury,"
and (4) whether the evidence meets the test of CRE 403.
People v. Shreck, 22 P.3d 68, 70 (Colo. 2001).
Recently, the supreme court again explained the trial
court's gatekeeper function:
[T]he trial court's inquiry should be broad in nature and
take into consideration the totality of the circumstances of
each specific case, focusing on both the reliability and
relevance of the evidence. In light of the wide range of
factors that may be considered in any individual case and the
liberal nature of the standard, we imposed upon trial courts
admitting evidence pursuant to CRE 702 an obligation to first
determine and make specific findings on the record, not only
as to the reliability of the scientific principles upon which
the expert testimony is based and the qualifications of the
witness giving that testimony, but also the usefulness of
such testimony to the jury, including specific findings with
regard to the court's obligation pursuant to CRE 403 to
ensure that the probative value of the evidence would not be
substantially outweighed by any of the countervailing
considerations enumerated in the rule.
Ruibal v. People, 2018 CO 93, ¶ 12 (citations
18 Expert testimony should be admitted only when the
expert's opinions will be helpful to the fact finder.
People v. Valdez, 183 P.3d 720, 723 (Colo.App.
2008). "Helpfulness to the jury hinges on whether the
proffered testimony is relevant to the particular case:
whether it 'fits.'" People v. Martinez,
74 P.3d 316, 323 (Colo. 2003).
Fit demands more than simple relevance; it requires that
there be a logical relation between the proffered testimony
and the factual issues involved in the litigation. That is,
even if good grounds exist for the expert's opinion, it
must be validly and scientifically related to the issues in
the case. That particular expert testimony fits or is valid
for one facet or purpose of a proceeding does not necessarily
compel the conclusion that it fits all facets. Therefore, the
admissibility of evidence must be evaluated in light of its
Id. (citations omitted).
19 There are two substantial risks associated with the
admission of blind expert testimony. The first is that, as
the supreme court recognized in Venalonzo (and as
the trial court explicitly recognized in this case), most, if
not all, expert testimony has the tendency to bolster the
credibility of one or more witnesses. Venalonzo,
¶¶ 32, 36. When an expert explains why a witness
might have acted in a counterintuitive manner, that
explanation may bolster the credibility of that witness.
20 But, "while such 'testimony may incidentally give
rise to an inference that a victim is or is not telling the
truth about the specific incident,' 'this fact alone
is insufficient to deny admission of the evidence, because
expert testimony generally tends to bolster or attack the
credibility of another witness.'" Relaford,
¶ 30 (quoting People v. Koon, 724 P.2d 1367,
1370 (Colo.App. 1986)). That is, the bolstering effect is
acceptable when the expert testimony is necessary to educate
the jury regarding matters about which the ordinary juror has
no knowledge. When that is not the case, however, the
bolstering effects of expert testimony are unacceptable.
21 The second danger of blind expert testimony is that the
jury may find or infer that historical facts existed based
solely on the expert's testimony, rather than on the
historical evidence presented to the jury. On at least two occasions
the supreme court has recognized a similar danger in other
22 In the jury instruction context in Castillo v.
People, 2018 CO 62, the supreme court addressed the
first aggressor exception to self-defense and, more
specifically, whether an erroneously given first aggressor
instruction was harmless when there was no evidence
supporting the instruction. A division of this court had
reasoned that even if there was no evidence to support it,
the error was harmless because if there was no evidence to
support the instruction, the jury would simply disregard it.
Id. at ¶ 47.
23 Rejecting that analysis, the supreme court stated that
"we have repeatedly expressed concern that jurors might
try to fit facts into an erroneously given instruction."
Id. at ¶ 59. As the supreme court concluded in
an earlier case, "[d]uring deliberations, it is possible
that the jury may have wondered why it was given the
instruction, decided that it must have been for some purpose,
and forced the evidence to fit the instruction, thereby
denying [defendant] his claim to self-defense."
Kaufman v. People, 202 P.3d 542, 562 (Colo. 2009).
The Castillo court relied on its earlier decision in
Barnhisel v. People, 141 Colo. 243, 246, 347 P.2d
915, 917 (1959), where the court observed that an instruction
which correctly states the law but is not supported by
evidence erroneously "implies or assumes the existence
of evidence not in the record."
24 The supreme court also explained that the danger of giving
a jury instruction that is not supported by the evidence is
"exacerbated by the prosecution's misleading
comments during its closing ...