A trial court
may permit a witness who is qualified “by knowledge, skill, experience,
training, or education” to testify as an expert, if it determines that
“scientific, technical, or other specialized knowledge will assist the trier of
fact to understand the evidence or to determine a fact in issue.” MRE 702.
However, trial courts must be vigilant to ensure that the expert’s testimony
remains within proper bounds: There is
always the concern that jurors will disregard their own common sense and give
inordinate or dispositive weight to an expert’s testimony. See People v Peterson, 450 Mich 349, 374
(1995) (noting the potential that a jury might defer to an expert’s seemingly
objective view of the evidence). For that reason, trial courts must—at every
stage of the litigation—serve as the gatekeepers who ensure that the expert and
his or her proposed testimony meet the threshold requirements. Gilbert v DaimlerChrysler Corp, 470
Mich. 749, 782 (2004).
A trial court errs when it abandons
its duty to ensure the integrity of the expert’s testimony or performs its
gatekeeper function inadequately. Gilbert, 470 Mich at 780. Where the proffered
testimony is not relevant or not helpful because it does not involve matters
beyond the common understanding of jurors, it is inadmissible under MRE 702. People v Kowalski, 492 Mich 106, 121-122
(2012). In addition to the requirements
provided under MRE 702, trial courts must ensure that an expert’s testimony
complies with the general rules of admissibility. See MRE 401, MRE 402, and MRE
403. Applying all these rules, courts have developed specific limitations on
expert testimony that implicate a defendant’s right to have an impartial jury
find the facts. As Justice Brickley explained in the context of a criminal
sexual conduct case, because of the danger that jurors might be tempted to
defer to an expert on the issue of guilt, courts have established “appropriate
safeguards” to accommodate the need for expert testimony in specific circumstances
while avoiding the possibility that a jury might unduly rely on the expert’s testimony: Given the nature of the offense and the
terrible consequences of a miscalculation—the consequences when an individual,
on many occasions a family member, is falsely accused of one of society’s most
heinous offenses, or, conversely, when one who commits such a crime would go
unpunished and a possible reoccurrence of the act would go
unprevented—appropriate safeguards are necessary. To a jury recognizing the
awesome dilemma of whom to believe, an expert will often represent the only
seemingly objective source, offering it a much sought-after hook on which to
hang its hat. [People v Beckley, 434
Mich 691, 721-722 (1990).
An expert may
testify regarding the characteristics of sexually abused children, but only for
the purpose of explaining potentially unusual behaviors. Peterson, 450 Mich at
365. The expert may not offer an opinion
as to whether the victim was actually abused. Id. A prosecutor may not present
expert testimony on the characteristics of drug dealers—commonly referred to as
profile evidence—in order to establish that the defendant was in fact a drug
dealer. People v Hubbard, 209 Mich App 234, 241-242 (1995). The prosecutor
may, however, present such evidence as background or modus operandi evidence,
but the trial court and the parties must be careful to ensure that the
testimony is not offered as substantive evidence of guilt and the expert should
not be permitted to opine that the defendant is guilty or otherwise testify in
such a way as to imply that the defendant is guilty. People v Williams, 240 Mich App 316, 320-321; 614 NW2d 647 (2000).
Although an expert’s testimony may “embrace”
ultimate issues to be decided by the jury, see MRE 704, the expert may
not generally offer an opinion on fault, guilt, or a witness’ truthfulness. See
Kowalski, 492 Mich at 129 (stating that an expert may testify about the
phenomena of false confessions and interrogation techniques, but may not
comment on the truthfulness of a defendant’s confession); People v McGillen, 392 Mich 278, 285-286 (1974) (stating that a
medical doctor cannot offer expert testimony that the victim was actually raped
or that she is truthful); O’Dowd v
Linehan, 385 Mich 491, 513 (1971) (holding that it was error to allow the
expert to “fix the blame for the accident” because there was nothing
exceptional about the evidence that required an expert opinion on the ultimate
issue).
With regard to
evidence concerning gang membership and gang culture, there are no published
Michigan authorities that specifically address its permissible scope.
Nevertheless, other courts have held that such testimony can be helpful to
jurors. See People v Memory, 182 Cal
App 4th 835, 858 (2010) (stating that evidence of gang membership is admissible
to prove motive); New Jersey v Torres,
183 NJ 554, 569; 874 A2d 1084 (2005) (listing cases where courts have
determined that expert testimony about gangs and gang culture is relevant and
helpful to the jury); United States v
Mansoori, 304 F3d 635, 654 (CA 7, 2002) (holding that the police expert’s
testimony on the history, structure, and involvement of the Travelling Vice
Lords gang was useful to the jury); United States v Lemon, 239 F3d 968, 971 (CA
8, 2001) (“Evidence of gang membership is admissible if relevant to a disputed
issue.”); United States v Hankey, 203 F3d 1160 (CA 9, 2000) (stating that a
police expert could testify about the defendants’ gang affiliations and general
tenets of gang culture to impeach testimony). Nevertheless, courts have recognized
the high potential that such evidence will be unduly prejudicial. In United
States v Garcia, 151 F3d 1243 (CA 9, 1998), the court reversed a
defendant’s conviction for conspiracy because the only evidence that the
prosecutor presented in support of the conspiracy was evidence that the
defendant was in a gang: Recent authority in this circuit establishes that
“[m]embership in a gang cannot serve as proof of intent, or of the
facilitation, advice, aid, promotion, encouragement or instigation needed to
establish aiding and abetting.” Mitchell
v Prunty, 107 F3d 1337, 1342 (CA 9, 1997), cert denied, 522 US 913, 118 S
Ct. 295; 139 L Ed 2d 227 (1997), overruled in part on other grounds, Santamaria v Horsley, 133 F3d 1242 (CA
9, 1998) (en banc). In overturning the state conviction of a gang member that
rested on the theory that the defendant aided and abetted a murder by “fanning
the fires of gang warfare,” the Mitchell [court] expressed concern that
allowing a conviction on this basis would “smack[ ] of guilt by association.”
Id. at 1342. The same concern is implicated when a conspiracy conviction is
based on evidence that an individual is affiliated with a gang which has a
general rivalry with other gangs, and that this rivalry sometimes escalates
into violent confrontations. [Id. at 1246.]
Although there may be evidence that gang members are generally looking
for trouble or prepared for violence, that evidence does not itself establish
that they have actually made plans to initiate it and, for that reason, it is
not evidence of a criminal conspiracy. Id. Further, the court warned that
allowing evidence of gang membership to serve as evidence of aiding and
abetting or conspiracy would invite absurd results: “Any gang member could be
held liable for any other gang member’s act at any time so long as the act was predicated
on the common purpose of fighting the enemy.” Id. (internal quotations and
citation omitted). Accordingly, expert testimony that a defendant is in a gang
and that the gang members have a basic agreement to back one another up in
fights is insufficient to establish a conspiracy to commit assault or other
illegal acts. Id. at 1245-1246. Where an expert testifies about gang membership
and culture, trial courts must be certain to ensure that the jury does not get
the impression that gang membership alone equates to guilt. Evidence regarding
the beliefs and practices of an organization may be relevant to explain a
member’s conduct on a particular occasion, but only with an appropriate
foundation and limitations. Memory,
182 Cal App 4th at 862. When admitted without a proper foundation and an
appropriate limiting instruction, there is a danger that the jury will make an
improper inference: “Membership in an organization does not lead reasonably to
any inference as to the conduct of a member on a given occasion. Hence, the
evidence was not relevant. It allowed, on the contrary, unreasonable inferences
to be made by the trier of fact that the [defendant] was guilty of the offense
on the theory of ‘guilt by association.’” [Id. at 859 (citation omitted).] See
also Kennedy v Lockyer, 379 F3d 1041,
1055-1056 (CA 9, 2004) (stating that evidence of gang membership cannot be
introduced to prove a substantive element of the crime, such as intent, because
it amounts to guilt by association); Mansoori,
304 F3d at 654 (noting that the expert testified that membership is not a crime
and that membership in the gang does not necessarily indicate that the member
is involved in illegal activities and that the trial court instructed the jury
that it is not illegal to be a member of, or associated with, a gang); United States v Roark, 924 F2d 1426 (CA
8, 1991) (ordering a new trial because the government’s witnesses’ testimony
about the Hell’s Angels organization unfairly introduced improper propensity
evidence and transformed the theme of the trial into one of guilt by
association).
An expert may
not testify that the defendant is guilty, or offer an opinion that a disputed
act actually occurred. Peterson, 450
Mich at 365; McGillen, 392 Mich at
285-286. Similarly, although evidence that a defendant is a member of a gang
implicates improper propensity evidence, when the evidence is admitted for a
relevant purpose and the jury is properly instructed on the limits of evidence,
it may be admissible under MRE 404. People
v VanderVliet, 444 Mich 52, 74-75 (1993); Memory, 182 Cal App 4th at 862.
