Must an expert’s opinion be excluded if they do not cite any supporting professional literature? “Not necessarily,” said the Michigan Court of Appeals in Janowski v. Deere & Co., No. 340665 (Mich. Ct. App. Jul. 11, 2019). There, the Court of Appeals affirmed a trial court decision admitting testimony from a lawnmower expert in a design defect personal injury case where a parent backed over their child’s foot on a riding mower.

A key issue at trial was whether “no mow while in reverse” (NMIR) technology could have prevented the accident. The parties offered competing expert testimony on this issue. After trial, the plaintiff appealed the decision to admit the testimony of defense expert David Stricker, whose testimony was based upon personal knowledge and experience, rather than industry literature.

The Court of Appeals described Stricker’s qualifications:

Stricker is an agricultural engineer who worked for Deere for 40 years and continues to consult with the company. Stricker served as the manager of Deere’s product development and product engineering services divisions. He managed the group that designed the mower deck used in the subject tractor. Stricker described in considerable detail the design choices that went into the production of the mower, a process in which he was directly involved. Stricker also chaired Deere’s product safety committee from 1999 through 2009.

The plaintiff nonetheless argued that Stricker’s testimony should be excluded, “asserting that his failure to produce any literature or other information supporting his expert opinions rendered those opinions unreliable.” The Court of Appeals rejected this argument; it explained that there is no bright line rule requiring that an expert cite literature to support an opinion. Instead, “[t]he overarching question [for the court] is whether the expert’s testimony has a reliable basis in the knowledge and experience of the relevant discipline.”

To reach this decision, the Court of Appeals analyzed Michigan Rule of Evidence 702, which follows the familiar requirements of Daubert.

A Daubert analysis does not hinge on discovering “absolute truth” or “resolv[ing] genuine scientific disputes.” Chapin v A & L Parts, Inc, 274 Mich. App. 122, 127; 732 N.W.2d 578 (2007) (opinion by DAVIS, J.). Rather, the trial court is tasked with filtering out unreliable expert evidence. “The inquiry is into whether the opinion is rationally derived from a sound foundation.” Id. at 139. “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.” People v Unger, 278 Mich. App. 210, 217-218; 749 N.W.2d 272 (2008).

The Court of Appeals explained that the Michigan Supreme Court “implicitly expressed the same view by pointing out that the Daubert factors are relevant to an inquiry under MRE 702 ‘even if all of the factors may not necessarily apply in determining the reliability of scientific testimony.’”

Focusing on reliability, the Court of Appeals held that the trial court did not abuse its discretion in admitting Stricker’s testimony. First, much of his testimony was fact testimony based upon his experience working for the defendant. Rule 702 does not apply to fact testimony. Second, his expert testimony was not unreliable because it was supported by both personal experience and industry standards.

Although Stricker did not produce any peer-reviewed literature specifically stating that an NMIR feature was an unnecessary, unsafe, or otherwise inappropriate option, application of several of the factors listed in MCL 600.2955(1) [the Michigan statute governing experts in personal injury cases] also support the reliability of his views. Subsection (c) references “[t]he existence and maintenance of generally accepted standards governing the application and interpretation of a methodology or technique and whether the opinion and its basis are consistent with those standards . . . . [T]he standard discussed at trial, ANSI B71.1, did not require an NMIR feature at the time the mower was manufactured. Stricker’s testimony was consistent with that standard. Subsection (f) addresses “[w]hether the basis for the opinion is reliable and whether experts in that field would rely on the same basis to reach the type of opinion being proffered.” That the overwhelming majority of manufacturers did not include NMIR features in 1994 demonstrates that other experts in lawnmower design considered it unnecessary or inappropriate for other reasons. And Stricker’s lengthy discourse regarding Deere’s internal design process satisfies subsection (g), which asks “[w]hether the opinion or methodology is relied upon by experts outside of the context of litigation.”

Stricker’s opinions that backover injuries are rare and best addressed with warnings and design modifications that reduce the need for operators to shift into reverse also finds support outside of Stricker’s mere “say so.” Deere’s calculation of the number of backover injuries per mower use was unchallenged during the trial, substantiating that backover injuries are, in fact, relatively uncommon.