Dowdy

IN THE UNITED STATES DISTRICT COURT

FOR THE SOUTHERN DISTRICT OF ILLINOIS

WILLIAM K. DOWDY,

Plaintiff,

v. Case No. 23-CV-02875-SPM

UNITED SEATING AND MOBILITY,

LLC, d/b/a NUMOTION,

Defendant.

MEMORANDUM AND ORDER

McGLYNN, District Judge:

This matter is before the Court on a Motion to Strike filed by Defendant United

Seating and Mobility, LLC d/b/a NuMotion (“NuMotion”). (Doc. 81). Having been fully

informed of the issues presented, Plaintiff’s Motion is DENIED.

RELEVANT FACUTAL AND PROCEDURAL BACKGROUND

This case arises from an incident in which Plaintiff William Dowdy was injured

after falling from a temporary wheelchair while using his wheelchair ramp. (Doc. 1,

Ex. A). The temporary wheelchair had been supplied by NuMotion while Dowdy’s

regular wheelchair was being serviced and repaired. (Id., Ex. A, ¶ 6).

On July 13, 2023, Dowdy filed a Complaint in Illinois state court alleging that

NuMotion provided him with a defective wheelchair and was therefore responsible

for his injuries. (Id., Ex. A). NuMotion removed the action to federal court based on

diversity jurisdiction. (Doc. 1). After several amendments and motions to dismiss, the

Court permitted Dowdy to proceed on three claims against NuMotion: (1) strict

liability, (2) negligence, and (3) breach of the warranty of merchantability. (Docs. 26,

29, 31, 42, 49, 56, 59). Discovery has concluded, and with no summary judgment

motions filed, the case is now proceeding to trial.

In advance of trial, NuMotion filed the present Motion to Strike under Federal

Rule of Evidence 702, challenging the admissibility of Plaintiff’s expert Mark Erza.

(Doc. 81). Plaintiff filed a Response (Doc. 89), and the time for filing a Reply has

passed; accordingly, the matter is ripe for review.

LEGAL STANDARD

To begin, “[a] district court’s decision to exclude expert testimony is governed

by Federal Rules of Evidence 702 and 703, as construed by the Supreme Court in

Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993).” Brown v. Burlington N.

Santa Fe Ry. Co., 765 F.3d 765, 771 (7th Cir. 2014); see also Lewis v. Citgo Petroleum

Corp., 561 F.3d 698, 705 (7th Cir. 2009). The standard applies to all expert testimony,

whether based on scientific competence or other specialized or technical expertise.

Smith v. Ford Motor Co., 215 F.3d 713, 719 (7th Cir. 2000) (citing Kumho Tire Co.,

Ltd. v. Carmichael, 526 U.S.137, 141 (1999)).

Federal Rule of Evidence 702 provides:

If scientific, technical or other specialized knowledge will assist the trier

of fact to understand the evidence or to determine a fact in issue, a

witness qualified as an expert by knowledge, skill, experience, or

training or education may testify thereto in the form of an opinion or

otherwise.

“In short, the rule requires that the trial judge ensure that any and all expert

testimony or evidence admitted ‘is not only relevant, but reliable.’” Manpower, Inc. v.

Ins. Co. of Pa., 732 F.3d 796, 806 (7th Cir. 2013) (quoting Daubert, 509 U.S. at 589).

In determining whether expert testimony is both relevant and reliable, courts in the

Seventh Circuit perform a three-step analysis: “the witness must be qualified ‘as an

expert by knowledge, skill, experience, training, or education,’ FED. R. EVID. 702; the

expert’s reasoning or methodology underlying the testimony must be scientifically

reliable, Daubert, 509 U.S. at 592–93; and the testimony must assist the trier of fact

to understand the evidence or to determine a fact in issue.” Ervin v. Johnson &

Johnson, Inc., 492 F.3d 901, 904 (7th Cir. 2007) (citing FED. R. EVID. 702).

“[W]here such testimony’s factual basis, data, principles, methods, or their

application are called sufficiently into question . . . the trial judge must determine

whether the testimony has ‘a reliable basis in the knowledge and experience of [the

relevant] discipline.’” Kumho, 526 U.S. at 149 (quoting Daubert, 509 U.S. at 592). “A

Daubert inquiry is not designed to have the district judge take the place of the jury

to decide ultimate issues of credibility and accuracy.” Lapsley v. Xtek, Inc., 689 F.3d

802, 805 (7th Cir. 2012). “If the proposed expert testimony meets the Daubert

threshold of relevance and reliability, the accuracy of the actual evidence is to be

tested before the jury with the familiar tools of ‘vigorous cross-examination,

presentation of contrary evidence, and careful instruction on the burden of proof.’” Id.

(quoting Daubert, 509 U.S. at 596). The district court possesses “great latitude in

determining not only how to measure the reliability of the proposed expert testimony

but also whether the testimony is, in fact, reliable.” United States v. Pansier, 576 F.3d

726, 737 (7th Cir. 2009) (citing Jenkins v. Bartlett, 487 F.3d 482, 489 (7th Cir. 2007)).

Lastly, the “proponent of the expert bears the burden of demonstrating that the

expert’s testimony would satisfy the Daubert standard” by a preponderance of the

evidence.” Lewis, 561 F.3d. at 705.

DISCUSSION

NuMotion seeks to exclude the testimony of Plaintiff’s expert Mark Ezra,

arguing that he lacks the proper qualifications, that his opinions rest on speculation

rather than reliable methodology, and that his testimony will not assist the jury. (Doc.

81). Plaintiff responds that Ezra is a seasoned mechanical engineer who applied

established engineering principles to the facts of this case, and that NuMotion’s

objections go to weight, not admissibility. (Doc. 89). After reviewing the parties’

submissions and the record, the Court concludes that Ezra’s testimony satisfies Rule

702.

The Court begins with Ezra’s qualifications. NuMotion emphasizes that Ezra

is not a biomechanical engineer, has never worked for a wheelchair supplier, and has

no experience as an Assistive Technology Professional (“ATP”). (Doc. 81, ¶¶ 11–14,

20, 33–35). But Rule 702 does not require an expert to hold a particular subspecialty

certification or to have worked in the defendant’s industry. See Gayton v. McCoy, 593

F.3d 610, 617 (7th Cir. 2010). The question is whether the witness possesses

“knowledge, skill, experience, training, or education” that will assist the trier of fact.

FED. R. EVID. 702. Ezra is a board-certified professional engineer with a degree in

mechanical engineering and a diploma in automatic control systems. (Doc. 89, Ex. B,

pp. 37–38). His professional background includes decades of engineering practice,

mechanical failure analysis, and forensic investigation. (Id.). Mechanical engineering

is directly relevant to the design, stability, braking systems, and mechanical behavior

of powered wheelchairs—the very issues at the heart of this case. This Court

therefore finds that Plaintiff has shown by a preponderance of the evidence that Ezra

is qualified to offer expert testimony.

The Court next considers reliability. NuMotion argues that Ezra’s opinions

lack a factual foundation, that he improperly relies on the testimony of ATP Vincent

Fels, and that he cannot identify the precise electrical defect that caused the

wheelchair to stop. (Doc. 81, ¶¶ 15–23, 36–39, 44–46). The Court finds these

arguments unpersuasive.

Ezra’s expert report reflects a systematic engineering analysis grounded in

physical inspection, measurements, documentary review, and application of

mechanical principles. He personally inspected the TSS 300 wheelchair, took custody

of it, and measured the slope of Plaintiff’s ramp. (Doc. 89, Ex. B, pp. 3–5). He reviewed

the owner’s manuals for both the TSS 300 and the Jazzy 600, analyzed their braking

systems, and compared their wheel configurations and stability characteristics. (Id.,

Ex. B., pp. 7–15). He considered Plaintiff’s prior successful use of both wheelchairs on

the same ramp and applied simple Newtonian mechanics to explain how a sudden

stop would eject a seated user. (Id., Ex. B., pp. 8–11, 13–14). Based on this analysis,

Ezra concluded that the “most probable and direct cause” of the incident was a power

failure in the TSS 300’s electrical system, which triggered the automatic deployment

of the parking brakes. (Id., Ex. B., pp. 18–19). He further explained why regenerative

braking could not account for the abrupt stop described by Plaintiff. (Id., Ex. B., p.

18).

This methodology of identifying possible mechanical causes, ruling out

alternatives, and applying engineering principles to the physical evidence is

consistent with accepted practices in mechanical failure analysis. The fact that Ezra

cannot identify the specific electrical component that failed does not render his

opinion unreliable. Experts are not required to pinpoint the exact microscopic failure

mechanism where the available evidence supports a broader, scientifically grounded

conclusion. See Lapsley, 689 F.3d at 815. Ezra’s reasoning is transparent, testable,

and rooted in the materials he reviewed.

NuMotion also contends that Ezra improperly relied on ATP Fels’s testimony

to opine on warnings and training. (Doc. 81, ¶¶ 15–17). But Ezra’s core opinions

concern mechanical behavior like stability, braking forces, and the consequences of a

sudden stop, not ATP standards of care. The Court concludes that his references to

Fels’s testimony serve only to contextualize the absence of instruction and the

differences between the two wheelchairs, not to substitute himself for an ATP. (Doc.

89, Ex. B, pp. 14–16). To the extent NuMotion believes Ezra strays beyond his

expertise, that concern is best addressed through cross-examination, not exclusion.

Finally, the Court considers relevance. NuMotion argues that Ezra’s testimony

will not assist the jury because he cannot say whether NuMotion caused the defect or

could have prevented it. (Doc. 81, ¶¶ 29–32, 36–37, 46). But Rule 702 does not require

an expert to resolve every element of liability. Ezra’s testimony will help the jury

understand the mechanical forces at play, the behavior of the TSS 300 during

braking, the significance of the design differences between the TSS 300 and the Jazzy

600, and the mechanical plausibility of Plaintiff’s account. These matters are well

outside the knowledge of a lay juror. Whether NuMotion caused the defect is a

separate question for the jury, informed by, but not dependent on, Ezra’s mechanical

analysis.

In short, NuMotion’s objections challenge the strength of Ezra’s conclusions,

not the admissibility of his methods. Under Daubert, such challenges are properly

addressed through “vigorous cross-examination, presentation of contrary evidence,

and careful instruction on the burden of proof,” not exclusion. 509 U.S. at 596. The

Court therefore concludes that Ezra’s testimony is admissible under Rule 702.

CONCLUSION

For the reasons set forth above, the Court holds that the NuMotion’s objections

to Plaintiff’s expert implicate the weight, not the admissibility, of their testimony.

Accordingly, NuMotion’s Motion to Strike (Doc. 81) is DENIED.

IT IS SO ORDERED.

DATED: April 1, 2026

s/ Stephen P. McGlynn

STEPHEN P. McGLYNN

U.S. District Judge