Chapter 7: Expert Testimony & Scientific Evidence
Part I—Expert Testimony
7.1Expert Testimony1
Admission of expert testimony at trial is governed by MRE 702:
“A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that:
(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.” MRE 702.
In People v Muhammad, 326 Mich App 40, 51-52 (2018), the Court described in detail the inquiry a trial court must conduct under MRE 702 before admitting expert testimony. According to the Court, “MRE 702 incorporates the standards of reliability that the United States Supreme Court established in [Daubert v Merrell Dow Pharm, Inc, 509 US 579 (1993)], in interpreting the equivalent federal rule of evidence.” Muhammad, 326 Mich App at 51-52.2 Factors to be considered in the trial court’s inquiry are (1) whether the scientific knowledge has been tested, (2) whether it has been subjected to peer review and publication, (3) the proven or potential rate of error, (4) whether standards of controlling the scientific operation exist and are maintained, and (5) whether the scientific operation has gained general acceptance. Id. at 52, citing Daubert, 509 US at 593-594. “However, these factors are not exclusive[.]” Muhammad, 326 Mich App at 52. “Although the Daubert gatekeeping function applies to all experts, the list of factors in Daubert is flexible and nonexhaustive: ‘Daubert’s list of specific factors neither necessarily nor exclusively applies to all experts or in every case.’” Danhoff v Fahim, ___ Mich ___, ___ (2024), quoting Kumho Tire Co, Ltd v Carmichael, 526 US 137, 141 (1999). “[E]ach case will present unique circumstances for a trial court to determine whether the expert’s opinion is reliable.” Danhoff, ___ Mich at ___.
As with all evidence, the proposed expert testimony must also be relevant under MRE 401 and MRE 402, and its probative value must not be “substantially outweighed” by a danger of “unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence.” MRE 403. On request, the trial judge may decide that a limiting instruction is appropriate. See People v Christel, 449 Mich 578, 600 (1995) (finding expert testimony regarding battered woman syndrome irrelevant and not helpful to explain any fact in issue).
According to MRE 702, a qualified expert witness is “[a] witness who is qualified as an expert by knowledge, skill, experience, training, or education [who] may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that [the requirements of MRE 702(a)-(d) are met].”MRE 702 does not require that an expert be certified by the state in the particular area in which the expert is qualified.” People v Brown, 326 Mich App 185, 196 (2018). Accordingly, a nurse who “held an associate’s degree in nursing and a nursing license, received sexual assault training through an online course, had worked at [a program that assists sexual assault victims] since 2009, and had performed approximately 30 examinations as a sexual assault nurse examiner” was properly qualified as an expert witness even though she had not yet received her certification as a SANE nurse. Id.
How a witness’s expertise compares to that of others in the field is relevant to the weight rather than the admissibility of the witness’s testimony and is a question for the jury. See Grow v W A Thomas Co, 236 Mich App 696, 713-714 (1999) (trial court properly permitted a certified social worker to testify as an expert in post-traumatic stress disorder). “In cases involving sexual abuse of children, expert testimony has been presented by physicians, crisis counselors, social workers, police officers, and psychologists.” People v Beckley, 434 Mich 691, 711 (1990) (opinion by Brickley, J.). The individuals in those categories or groups, and others in similar positions, are sometimes referred to as “skilled witnesses.” Id.
B.Expert Testimony Will Assist the Trier of Fact
A trial court acts as a gatekeeper to assure that expert testimony is properly admitted in a case. See People v Muhammad, 326 Mich App 40, 52 (2018). “‘[T]he trial court’s role as gatekeeper does not require it to search for absolute truth, to admit only uncontested evidence, or to resolve genuine scientific disputes.’” Id. (quotation marks and citations omitted).
Before admitting expert testimony, “[t]he trial court must also ensure that the expert’s testimony is relevant. Even when an expert’s testimony is relevant, it remains subject to the limits imposed by MRE 403.”3 People v McFarlane, 325 Mich App 507, 518 (2018) (citation omitted).
“‘The critical inquiry with regard to expert testimony is whether such testimony will aid the factfinder in making the ultimate decision in the case.’” People v Ackerman, 257 Mich App 434, 445 (2003) (affirming the trial court’s conclusion “that testimony about the typical patterns of behavior exhibited by child sexual abuse offenders would aid the jury”), quoting People v Coy, 243 Mich App 283, 294-295 (2000) (quotation marks and citation omitted). Deciding “whether an untrained layman could determine intelligently and to the best possible degree the issue involved without the aid of experts” requires only common sense. Ackerman, 257 Mich App at 445.
C.Expert Testimony Is Based on Sufficient Facts or Data
Sufficient facts or data must form the basis for a witness’s expert testimony. MRE 702.
“‘This gatekeeper role applies to all stages of expert analysis. MRE 702 mandates a searching inquiry, not just of the data underlying expert testimony, but also of the manner in which the expert interprets and extrapolates from those data. Thus, it is insufficient for the proponent of expert opinion merely to show that the opinion rests on data viewed as legitimate in the context of a particular area of expertise (such as medicine). The proponent must also show that any opinion based on those data expresses conclusions reached through reliable principles and methodology.’” People v Yost, 278 Mich App 341, 394 (2008), quoting Gilbert v DaimlerChrysler Corp, 470 Mich 749, 782 (2004).
MRE 703 requires that the facts or data on which an expert’s opinion is based be in evidence. MRE 703 states:
“An expert may base an opinion on facts or data in the case that the expert has been made aware of or personally observed. The facts or data must be in evidence—or, in the court’s discretion, be admitted in evidence later.”
“This rule permits an expert’s opinion only if that opinion is based exclusively on evidence that has been introduced into evidence in some way other than through the expert’s hearsay testimony.” People v Alexander, ___ Mich App ___, ___ (2024) (quotation marks and citation omitted). “To the extent that [an expert] relied on hearsay to formulate a diagnosis, and no hearsay exception applied, an expert is allowed to recount and rely on hearsay if it was used as a basis to form an opinion.” Id. at ___ (holding that the trial court did not err by allowing the expert testify as to her opinion of alleged abuse to one of defendant’s children because “[t]he facts and data underlying [the expert’s] testimony were fundamentally presented in testimony, documents, and photographs admitted [at trial]”). Id. at ___.
2.Disclosure of Facts in Support of Expert Testimony
MRE 705 governs disclosure of facts or data underlying an expert’s opinion. MRE 705 states:
“Unless the court orders otherwise, an expert may state an opinion—and give the reasons for it—without first testifying to the underlying facts or data. But the expert may be required to disclose those facts or data on cross-examination.”
D.Expert Testimony Results From Reliable Principles and Methods
“Under MRE 702, a trial court must ensure that all expert opinion testimony, regardless of whether it is based on novel science, is reliable.” People v Steele, 283 Mich App 472, 481 (2009). “‘MRE 702 requires the trial court to ensure that each aspect of an expert witness’s proffered testimony—including the data underlying the expert's theories and the methodology by which the expert draws conclusions from that data—is reliable.’” Steele, 283 Mich App at 481, quoting Gilbert v DaimlerChrysler Corp, 470 Mich 749, 779 (2004) (emphasis added). “‘Under MRE 702, it is generally not sufficient to simply point to an expert’s experience and background to argue that the expert’s opinion is reliable and, therefore, admissible.’“ Danhoff v Fahim, ___ Mich ___, ___ (2024) (citation omitted).4
A physician expert may testify concerning the alleged abuse of a victim when the opinion is made “on the basis of admitted evidence detailing physical findings and [the victim’s] medical history, in addition to the [victim’s] statements.” People v Alexander, ___ Mich App ___, ___ (2024), citing MRE 702. In Alexander, defendant was convicted of one count of torture, one count of second-degree child abuse, one count of second-degree child abuse in the presence of another child, and one count of third-degree child abuse. Alexander, ___ Mich App at ___. On appeal, defendant argued that the trial court plainly erred by allowing the prosecution’s expert witness—an expert in general pediatrics and child abuse pediatrics—to testify regarding the diagnosis of “medical torture” for two of the child victims. Id. at ___. The Court concluded that no error occurred, and stated that “an examining physician, if qualified by experience and training relative to treatment of the complainant, can opine with respect to the cause of the complainant’s injuries when the opinion is based on physical findings and the complainant’s medical history.” Id. at ___ (cleaned up).
“Expert testimony may be excluded when it is based on assumptions that do not comport with the established facts or when it is derived from unreliable and untrustworthy scientific data.” People v Dobek, 274 Mich App 58, 94 (2007). The Court explained why the expert testimony in Dobek was excluded:
“[T]he proffered expert testimony regarding sex-offender profiling was properly excluded because it [had] not reached a level of scientific reliability sufficient to permit admission, there was insufficient supporting data, and the testimony would not have assisted the jury in understanding the evidence or in determining a fact in issue; rather, the proffered evidence would have confused the issues, misled the jury, and caused unfair prejudice to the prosecutor.” Dobek, 274 Mich App at 107.
“Determining that [an] expert is unreliable and granting summary disposition without first considering [the] applicable factors [in MRE 702 and MCL 600.2955] is an abuse of discretion.” Danhoff, ___ Mich at ___ (a medical malpractice action where the trial court rejected plaintiff’s expert’s standard-of-care opinion testimony because it was not supported by published, peer-reviewed medical literature). According to the Court, “scientific literature is not always required to support an expert’s standard-of-care opinion, but . . . scientific literature is one of the factors that a trial court should consider when determining whether the opinion is reliable.” Id. at ___. “[T]he guidepost for admissibility is reliability, and trial courts must consider MRE 702 as well as the statutory reliability factors presented in MCL 600.2955 [for tort actions] when determining if an expert is reliable.” Danhoff, ___ Mich at ___.
Determining whether to permit expert testimony requires a trial court to consider whether “‘the opinion is rationally derived from a sound foundation.’” People v Muhammad, 326 Mich App 40, 52 (2018), quoting People v Unger, 278 Mich App 210, 217 (2008) (quotation marks and citation omitted). “‘The standard focuses on the scientific validity of the expert’s methods rather than on the correctness or soundness of the expert’s particular proposed testimony.’” Muhammad, 326 Mich App at 52-53, quoting Unger, 278 Mich App at 217-218.
E.Expert Reliably Applied Principles and Methods to the Facts
MRE 702(d) requires that “the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.” See also People v McFarlane, 325 Mich App 507, 518 (2018).
Although the Michigan Supreme Court does “not endorse or adopt the use of the term ‘syndrome,’” it has stated that “the admissibility of syndrome evidence is limited to a description of the uniqueness of a specific behavior brought out at trial.” People v Peterson, 450 Mich 349, 363 (1995). “[S]yndrome evidence is not admissible to demonstrate that abuse occurred and . . . an expert may not give an opinion whether the complainant is being truthful or whether the defendant is guilty.” Id. at 369. In addition, “where syndrome evidence is merely offered to explain certain behavior, the Davis/Frye[5] test for recognizing admissible science is inapplicable.” Peterson, 450 Mich at 369. See also People v Beckley, 434 Mich 691, 710 (1990); People v Smith, 205 Mich App 69, 73 (1994). In Beckley, the Court summarized its holding: “[E]vidence of behavioral patterns of sexually abused children is admissible ‘for the narrow purpose of rebutting an inference that a complainant’s postincident behavior was inconsistent with that of an actual victim of sexual abuse, incest or rape.’” Beckley, 434 Mich at 710 (citation omitted). “[O]nly those aspects of ‘child sexual abuse accommodation syndrome,’ which specifically relate to the particular behaviors which become an issue in the case are admissible.” Id.
Although a detective’s testimony was admitted as lay testimony, “[he] was more than qualified to give an expert opinion on delayed disclosure[6] to the extent of the testimony actually presented. [He] testified at length about his extensive knowledge, experience, training, and education concerning the sexual abuse of children. [He] ha[d] personally participated in the investigation of hundreds of criminal sexual conduct cases involving child victims. And [he] had received training in the investigation of cases involving delayed disclosure.” People v Dobek, 274 Mich App 58, 79 (2007).
H.Disqualification of Expert Witness
“‘[C]ourts are generally reluctant to disqualify expert witnesses, especially those . . . who possess useful specialized knowledge.’” Teutsch Estate v Van De Ven, 336 Mich App 604, 609 (2021), quoting Rhodes v E I Du Pont de Nemours & Co, 558 F Supp 2d 660, 664 (SD W Va, 2008) (quotation marks and citations omitted). An expert witness may be disqualified for conflict of interest when the party seeking disqualification claims to have shared confidential information with the expert witness before the opposing party ultimately procured the expert’s testimony for its own case. Teutsch Estate, 336 Mich App at 609-610.
I.Jury Instructions Related to Expert Testimony
M Crim JI 5.10, Expert Witness, is the jury instruction given at a criminal trial when expert testimony has been presented. M Crim JI 5.10 should not be used when expert testimony is presented “regarding the characteristics of sexually abused children and about whether the complainant’s behavior is consistent with those characteristics.”7 M Crim JI 5.10, Use Note.