1 

UNITED STATES DISTRICT COURT

FOR THE DISTRICT OF COLUMBIA

BRUCE BUNTING, et al.,

Plaintiffs,

v. 

 

DISTRICT OF COLUMBIA CVS 

PHARMACY, LLC, 

 

Defendant.

Civil Action No. 22-cv-766 

MEMORANDUM OPINION

Plaintiffs Dr. Bruce Bunting and Jessie Brinkley (“Plaintiffs”) bring this suit against 

Defendant District of Columbia CVS Pharmacy, LLC (“CVS”) for damages arising out of personal 

injuries that Dr. Bunting allegedly suffered during an incident at CVS’ premises in Northwest, 

Washington, D.C. (the “CVS Store”). ECF No. 1-1 at 1. 

 Before the Court is the Plaintiffs’ Motion to Strike All Opinion Testimony of Defendant’s 

Expert Witness Alexandra Maddox (“Motion”). ECF No. 45. For the following reasons, the Court 

DENIES Plaintiffs’ Motion.

FACTUAL SUMMARY

The Plaintiffs allege that on December 24, 2020, Dr. Bunting slipped and fell outside the 

automatic exit doors at the CVS Store. ECF No. 1-1 at 2. Dr. Bunting claims that he slipped on 

“slick and wet concrete that resulted from a mixture of salt and water.” Id. at 3. The Plaintiffs 

allege that CVS created the slick surface by “spreading [] the salt on a wet and warm day, which 

caused it to make the ground unsafe and slippery.” Id. at 3. According to the Plaintiffs, the CVS 

Store was “negligently kept, maintained, and operated, creating an unreasonable risk of injury to 

invitees,” including Dr. Bunting. Id. at 4. As a result of the fall, Dr. Bunting allegedly suffered a 
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“closed fracture dislocation of his right ankle” that required surgery. Id. at 3. The Plaintiffs further 

allege that CVS’ negligence caused Dr. Bunting to suffer “serious bodily and emotional injuries 

and damages, including physical pain, suffering, emotional distress, inconvenience, loss of the 

enjoyment of life, and medical expenses.” Id. at 4.

One of CVS’ designated expert witnesses is Alexandra Maddox, a mechanical engineer 

and biomedical engineer. ECF No. 33 at 4. Maddox’s expert report details her investigation, 

including slip resistance testing she conducted on January 19, 2023 on the incident walkway 

surface at the CVS Store, and provides her opinions regarding the slip resistance of the walkway

surface. ECF No. 33-5. As part of herslip resistance testing, Maddox used an English XL Variable 

Incident Tribometer (“VIT”), a device used for slip resistance testing in different environments. 

Id. at 9, 14. A VIT is designed to yield coefficient of friction (“COF”) measurements that correlate 

to the likelihood of slip incidents occurring on a given surface. Id. at 14. Maddox used a VIT that 

Excel Tribometers, the manufacturer of the English XL VIT, calibrated three days before her field 

test. Id. at 9. Maddox then field calibrated the VIT the day before her field test. Id. 

According to CVS, Maddox’s VIT was validated and calibrated in accordance with 

American Society for Testing and Materials (“ASTM”) standard F2508. ECF No. 49 at 1, 2. 

Maddox also applied American National Standards Institute (“ANSI”) standard A1264.2, which 

recommends a COF of 0.5 or greater for walking surfaces in the workplace under dry or wet 

conditions. ECF No. 33-5 at 4, 14. CVS asserts that Maddox “obtained slip resistance 

measurements under both wet and dry scenarios” pursuant to ANSI A1264.2. ECF No. 49 at 16. 

Consistent with the VIT device manual, Maddox used only water for the wet testing. Id. 
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Maddox concluded that the walkway surface had a COF of 0.64 ± .03 when dry and 0.51 

± .03 when wet.1 ECF No. 33-5 at 9. According to Maddox, the salt and water solution that Dr. 

Bunting described slipping on “is less lubricating than water on a walking surface, and creates 

greater slip resistance than water alone.” Id. at 16. Maddox therefore concluded, among other 

things, that “the incident walking surface was reasonably safe for pedestrian traffic” and “[t]here 

is insufficient evidence to support the claim that the incident walkway caused [Dr. Bunting’s] fall.” 

Id.

PROCEDURAL HISTORY

The Plaintiffs filed a Complaint on February 14, 2022 in the Superior Court of the District 

of Columbia. ECF No. 1 at 1. The Complaint includes three counts: (1) negligence – premises 

liability; (2) negligence per se; and (3) loss of consortium. ECF No. 1-1 at 4–8. The Plaintiffs 

seek the following relief: (1) compensatory damages in the amount of $2,000,000; (2) payment of 

all costs associated with this case; (3) pre- and post-judgment interest; and (4) “such other and 

further relief as this Court deems proper.” Id. at 8. CVS removed the case to this Court on March 

21, 2022 based on diversity of citizenship. ECF No. 1.

ANALYSIS

I. Standard of Review

The Plaintiffs seek to exclude all of Maddox’s opinion testimony pursuant to Rule 702 of 

the Federal Rules of Evidence, Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993), and

Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137 (1999). ECF No. 45 at 1. Under Rule 702, a 

1 As part of their response to CVS’ Motion for Summary Judgment (ECF No. 47), the 

Plaintiffs assert that after the close of discovery, CVS produced Maddox’s field notes that show 

that the area “directly outside the exit door where Dr. Bunting slipped and fell had an average 

coefficient of friction of 0.49 when wet.” ECF No. 52 at 1.
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district court “must determine as an initial matter whether the proffered witness is qualified to give 

the expert opinion he seeks to offer.” Moore v. Napolitano, 926 F. Supp. 2d 8, 16-17 (D.D.C. 

2013). The Court may then admit a qualified expert’s testimony only if it is both relevant and 

reliable. Id. at 17.

A. Expert Qualification Under Rule 702 and Daubert

As a general matter, “trial courts have broad discretion when deciding whether a witness 

qualifies as an expert.” 29 Charles Alan Wright & Arthur R. Miller, Federal Practice and 

Procedure (“Wright and Miller”) § 6264.2 (2d ed. 2023). Rule 702 recognizes five specific bases 

for qualifying an expert: knowledge, skill, experience, training, and education. Fed. R. Evid. 702. 

Background in just one of these bases is sufficient, but if an expert has some background in 

multiple bases, the Court may consider the totality of the witness’s background. Wright and Miller 

§ 6264.1. No matter which bases are at issue, the expert’s background must match the subject 

matter of the expert’s testimony. Id. § 6264.2.

A qualified expert may testify “if the proponent demonstrates to the court that it is more 

likely than not that,” among other things, “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.” 

Fed. R. Evid. 702(a). The degree of knowledge, skill, experience, training, or education required 

to qualify an expert witness “is only that necessary to insure [sic] that the witness’s testimony

assist the trier of fact.” Khairkhwa v. Obama, 793 F. Supp. 2d 1, 11 (D.D.C. 2011) (internal 

quotation marks omitted), aff’d, 703 F.3d 547 (D.C. Cir. 2012). A trial court may not exclude 

expert testimony “simply because [it] does not deem the proposed expert to be the best qualified 

or because the proposed expert does not have the specialization that the court considers most 

appropriate.” Heller v. D.C., 952 F. Supp. 2d 133, 140 (D.D.C. 2013). To that end, the relevant 

inquiry with respect to an expert’s qualifications is not her qualifications in the abstract, but 
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“whether those qualifications provide a foundation for a witness to answer a specific question.” 

Berry v. City of Detroit, 25 F.3d 1342, 1351 (6th Cir. 1994) (emphasis added).

In the context of slip-and-fall cases, federal courts have ruled that certified tribometrists

are qualified under Rule 702 to offer opinion testimony about the slip resistance of a walkway 

surface. See, e.g., Kessler v. NCL (Bahamas) Ltd., No. 19-CV-20583, 2019 WL 8128483, at *4 

(S.D. Fla. Dec. 20, 2019); Ward v. Carnival Corp., No. 17-CV-24628, 2019 WL 1228063, at *4 

(S.D. Fla. Mar. 14, 2019); Michaels v. Taco Bell Corp., Civ. No. 10-1051, 2012 WL 4507953, at 

*6 (D. Or. Sept. 27, 2012); Stern v. NCL Bahamas Ltd., No. 19-CV-20280, 2020 WL 6820877, at 

*5 (S.D. Fla. Sept. 28, 2020).

B. Reliability Under Rule 702 and Daubert

Daubert established the district court’s role as a “gatekeeper[] to exclude unreliable expert 

testimony.” U.S. ex rel. Miller v. Bill Harbert Int’l Const., Inc., 608 F.3d 871, 894 (D.C. Cir. 

2010) (citing Daubert, 509 U.S. at 579). In fulfilling its gatekeeper role, a district court has “broad 

discretion in determining whether to admit or exclude expert testimony.” Id. Although district 

courts may apply various factors to assess reliability, the Supreme Court provided the following

five factors to guide the inquiry: (1) whether the technique has been or can be tested; (2) whether 

the technique has a known or potential rate of error; (3) whether the technique has been subject to 

peer review and publishing; (4) the existence and maintenance of standards controlling the 

technique’s operation; and (5) whether the technique has been generally accepted within the 

relevant scientific community. Daubert, 509 U.S. at 593–94. Under Daubert, a trial court must 

focus “solely on principles and methodology, not on the conclusions that they generate.” Id. at 

595. Further, the Court need only determine whether the expert’s science “has the earmarks of 

validity” and not whether it is, in fact, scientifically valid. Wright & Miller § 6267. 
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This Court has stated that “[i]n considering Rule 702 motions, the court assumes only a 

limited gate-keeping role directed at excluding expert testimony that is based upon subjective 

belief or unsupported speculation.” Heller, 952 F. Supp. 2d at 140 (internal quotation marks 

omitted). Further, the Court “is supposed to screen the jury from unreliable nonsense opinions, 

but not exclude opinions merely because they are impeachable.” Alaska Rent-A-Car, Inc. v. Avis 

Budget Grp., Inc., 738 F.3d 960, 969 (9th Cir. 2013). According to the D.C. Circuit, expert 

testimony is not reliable when it is based on “guesswork, speculation, and conjecture.” Joy v. Bell 

Helicopter Textron, Inc., 999 F.2d 549, 568 (D.C. Cir. 1993). This Court has stated that “[e]xpert

testimony should be excluded only when it is based on ‘guesswork, speculation, and conjecture.’” 

United States v. Slough, 22 F. Supp. 3d 25, 29 (D.D.C. 2014) (quoting Joy, 999 F.2d at 568)

(emphasis added). To that end, “[t]he presumption under [Rule 702] is that expert testimony is 

admissible once a proponent makes the requisite threshold showing; further disputes go to weight, 

not admissibility.” United States v. Machado-Erazo, 950 F. Supp. 2d 49, 52 (D.D.C. 2013) (citing 

Daubert, 509 U.S. at 588). 

With respect to measuring slip resistance, a VIT is “commonly relied on by experts in slip 

and fall cases all over the United States.” Piazza v. Target Corp., No. 21-CV-835, 2022 WL 

16923867, at *1 n.1 (M.D. Fla. Nov. 14, 2022). Indeed, numerous federal courts have ruled that 

VIT testing is reliable under Rule 702. See, e.g., id.; Barnes v. Malinak, 320 F.R.D. 130, 139 (E.D. 

Tenn. 2017); Darby v. Carnival Corp., No. 19-21219-CIV, 2021 WL 6428039, at *10 (S.D. Fla. 

Nov. 23, 2021), adopted by, No. 19-21219-CIV, 2022 WL 112193 (S.D. Fla. Jan. 12, 2022); Armas 

v. Costco Wholesale Corp., No. 21-cv-01528, 2022 WL 17982239, at *5 (D. Nev. Nov. 30, 

2022); Feuerstein v. Home Depot, U.S.A., Inc., No. 12-cv-01062, 2014 WL 2616582, at *3 (D. 

Ariz. June 12, 2014); Atkinson v. Carnival Corp., No. 20-20317-CIV, 2021 WL 8534238, at *4 
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(S.D. Fla. Nov. 29, 2021); Steffen v. Home Depot U.S.A., Inc., No. CV-13-199, 2014 WL 1494108,

at *6 (E.D. Wash. Apr. 16, 2014). At least one federal court has based its denial of a Rule 702 

motion challenging the reliability of VIT testing in part on the fact that the expert’s VIT passed

ASTM F2508 validation. See Armas, 2022 WL 17982239, at *5.

In denying Rule 702 motions that challenge the reliability of VIT testing, federal courts 

have ruled that any alleged defects in the methodology of VIT testing go to the weight of the 

expert’s opinion, not its admissibility. See, e.g., Barnes, 320 F.R.D. at 139; Atkinson, 2021 WL 

8534238, at *4; Darby, 2021 WL 6428039, at *10. For example, although the court in Barnes 

noted that it was “concerned that [the expert] did not use the tribometer as the manufacturer 

intended and was not certain when the device had been calibrated,” it nonetheless denied the Rule 

702 motion because “‘vigorous cross-examination, presentation of contrary evidence, and careful 

instruction on the burden of proof are the traditional and appropriate means of attacking shaky but 

admissible evidence.’” 320 F.R.D. at 139 (quoting Daubert, 509 U.S. at 596).

II. The Plaintiffs’ Motion to Strike

A. Maddox Is Qualified to Offer Opinion Testimony Regarding the Slip 

Resistance of the Walkway Surface at the CVS Store.

The Plaintiffs argue that Maddox is not qualified under Rule 702 to provide expert 

testimony regarding the slip resistance of the walkway surface at the CVS Store. ECF No. 45-1 at 

17–19; ECF No. 51 at 1–3. In support of this argument, the Plaintiffs assert that “[a]ccording to 

her CV, Ms. Maddox is not a licensed professional engineer, a certified safety specialist, a certified 

Variable Incidence Tribometrist, or even a human factors expert and has no experience in testing 

or evaluating walking surfaces for slipperiness.” ECF No. 45-1 at 17. The Plaintiffs also assert

that Maddox’s ongoing work as a Ph.D. student is not related to walkway surfaces or testing of 

materials. Id. The Plaintiffs further argue that Maddox’s Occupational Safety and Health 
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Administration (“OSHA”) accreditations in general industry standards do not reflect an expertise 

in walkway safety because they were minimally focused on walkway safety and fall protection. 

ECF No. 51-1 at 2. 

In support of their argument, Plaintiffs cite a slip-and-fall case in which the expert “was a 

registered Professional Engineer, Certified Safety Professional, and Certified Variable Incidence 

Tribometrist, who [held] a [m]aster’s [d]egree in Industrial Safety Engineering and [a] Ph.D. in 

Interdisciplinary Engineering ‘with a focus on Workplace, Premises, Product Safety, Human 

Factors, and Industrial Engineering.’” ECF No. 45-1 at 17 (quoting Ruston v. Office Depot, Inc., 

No. 10-CV-05057, 2011 U.S. Dist. LEXIS 119558, at *3 (W.D. Mo. Oct. 17, 2011)). The Plaintiffs 

also cite cases outside the slip-and-fall context in which an expert appeared to be well educated, 

have extensive experience in a certain field, or both, but nonetheless failed to qualify under Rule 

702 because the expert did not possess the requisite knowledge, skill, experience, training, or 

education in the relevant field. Id. at 18–19 (citing Meridia Products Liability Litigation v. Abbott 

Laboratories, 447 F.3d 861, 868–69 (6th Cir. 2006); Brown v. Raymond Corp., 432 F.3d 640, 641, 

649–50 (6th Cir. 2005); and Advanced Med. Optics, Inc. v. Alcon Inc., No. 03-1095, 2005 U.S. 

Dist. LEXIS 5803, at *13 (D. Del. Apr. 7, 2005)). 

CVS argues that Maddox is qualified under Rule 702 to offer expert opinions on the slip 

resistance and reasonable safety of the walkway surface because, contrary to the Plaintiffs’ 

assertion, Maddox is a Certified English XL Tribometrist (“CXLT”) and “possesses a valid CXLT 

Certificate.” ECF No. 49 at 7. This certification process included classroom and field training 

provided by the device manufacturer and required Maddox to demonstrate proper operational 

technique of the device in both a written examination and a field proficiency test. Id. at 7–8. In 

light of Maddox’s CXLT certificate, CVS argues that “when the ‘specific question’ relates to the 
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slip resistance of a walkway surface, the federal district courts are uniform in finding that a 

certified tribometrist is qualified to offer those opinions.” Id. at 9 (citing Kessler, 2019 WL 

8128483, at *4; Michaels, 2012 WL 4507953, at *6; Stern, 2020 WL 6820877, at *5). It would 

be “illogical,” according to CVS, “for this Court to conclude that Ms. Maddox is not qualified to 

perform slip resistance testing using a VIT when the company that manufactures the very device 

that she used has certified that she is qualified to do so.” Id. 

According to CVS, “Rule 702 does not require an expert witness to possess a Ph.D. or to 

be a certified safety specialist to be qualified to render expert opinions on the slip resistance of a 

walkway surface.” Id. at 8 (internal quotation marks omitted). As a result, Maddox “more than 

meets the qualifications necessary to testify with respect to the testing she performed with a device 

she is certified to use, and the conclusions that she reached as a result of her testing and 

investigation.” Id. at 9. CVS also notes that Maddox “has a bachelor’s degree in biomedical 

engineering, has nearly completed her Ph.D., and has completed two accredited courses in OSHA 

general industry standards, including walkway safety.” Id. at 8.

The Court finds that Maddox is qualified under Rule 702 to offer opinion testimony 

regarding the slip resistance of the walkway surface at the CVS Store. The Plaintiffs are incorrect 

to suggest that Maddox is not a CXLT. Maddox obtained her CXLT certification “following 

classroom and field training provided by” the manufacturer of the VIT that Maddox later used to 

perform a field test of the walkway surface at the CVS Store. ECF No. 49-4 at 1–3. Maddox then 

detailed the results of that field test in her expert report and explained why those results led her to 

conclude, among other things, that the walkway surface “was reasonably safe for pedestrian 

traffic.” ECF No. 33-5 at 16. Importantly, Maddox’s certification applies not only to her operation 

of the VIT, but also to her “interpret[ation] of the results obtained in field tests utilizing the VIT.” 
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ECF No. 49-4 at 2. Given that the slip resistance of the walkway surface at the CVS Store is 

directly relevant to the Plaintiffs’ negligence claims, Maddox’s CXLT certification is sufficient to 

ensure that her testimony will “assist” the trier of fact under Rule 702. See Khairkhwa, 793 F. 

Supp. 2d at 11 (D.D.C. 2011); see also ECF No. 48-1 at 22 (providing Plaintiffs’ expert’s opinion 

that Dr. Bunting’s injury was caused by “a very slippery and an unreasonably unsafe and dangerous 

walkway surface condition.”).

As CVS notes, several federal courts have ruled that a certified tribometrist is qualified

under Rule 702 to offer opinion testimony about the slip resistance of a walkway surface. See, 

e.g., Kessler, 2019 WL 8128483, at *4; Ward, 2019 WL 1228063, at *4; Michaels, 2012 WL 

4507953, at *6; Stern, 2020 WL 6820877, at *5. Plaintiffs do not identify any case in which a 

court has ruled that a certified tribometrist is not qualified to offer opinion testimony about the slip 

resistance of a walkway surface. 

The outcome does not change merely because the experts in cases upon which CVS relies 

may have had stronger credentials than Maddox in this particular area. For example, the expert in 

Michaels had “substantial experience as a consulting engineer” in addition to being a certified 

tribometrist. 2012 WL 4507953, at *6. Similarly, the expert in Stern was a certified tribometrist 

who also specialized in slips, trips, falls, and industrial and premises safety, participated in crash 

investigations, and completed continuing education courses in accident reconstruction. 2020 WL 

6820877, at *5. This Court may not, however, exclude Maddox’s testimony simply because it 

believes Maddox is not “the best qualified” or because Maddox “does not have the specialization 

that the court considers most appropriate.” Heller, 952 F. Supp. 2d at 140. Maddox’s status as a 

CXLT renders her able to help the jury determine the slip resistance of the walkway surface at the 
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CVS Store and, in turn, whether CVS was negligent in its treatment of the walkway surface. See 

Fed R. Evid. 702(a). Maddox, therefore, meets the qualification standard under Rule 702. 

B. Maddox’s Opinion Testimony Meets the Threshold Requirements for 

Reliability.

Plaintiffs also argue that the Court should exclude all of Maddox’s opinion testimony 

because Maddox’s VIT testing methodology is “[u]nreliable [f]lawed [s]cience.” ECF No. 45-1 

at 9. Plaintiffs make several specific arguments regarding reliability. First, they argue that ASTM 

F2508 cannot be used to establish a safe threshold value for a walkway surface because: (1) it is 

based on VIT measurements from young adults walking in a straight path on a level surface, 

whereas Dr. Bunting was 73 years old at the time of the incident and was stepping over a door 

onto a slanted surface; (2) its test subjects walked in shoes that are not representative of all shoes; 

(3) its use does not imply proper validation and calibration under all combinations of test materials 

and walkway surfaces; and (4) it does not purport to address all safety concerns associated with its 

use. ECF No. 45-1 at 10–12. 

Second, Plaintiffs assert that recent studies and publications, including by ASTM, 

demonstrate the unreliability of VIT testing. Id. at 12–14. Third, the Plaintiffs note that, in 2006,

ASTM withdrew ASTM F1679—a VIT testing standard that ASTM originally published in 

2004—because it lacked precision and bias testing. ECF No. 45-1 at 14–15. According to 

Plaintiffs, ASTM F1679’s withdrawal illustrates that VIT testing is unreliable. Id. at 15. Fourth, 

Plaintiffs assert that Maddox has not demonstrated that she complied with ASTM’s calibration 

requirements to use a VIT. Id. at 16–17. Plaintiffs cite to Kill v. City of Seattle, No. 70767-1-I, 

2014 Wash. App. LEXIS 2094 (Ct. App. Aug. 25, 2014), in which the court ruled that an expert’s 

opinion testimony was unreliable because, among other things, the expert’s VIT “was not properly 
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calibrated under the ASTM F2508 standard at the time of [the expert’s] second field test.” Id. at 

*14; ECF No. 45-1 at 17; ECF No. 51 at 7.

In Maddox’s defense, CVS cites to various federal courts that have ruled that VIT testing 

is reliable under Rule 702. ECF No. 49 at 10–11. CVS also rejects the Plaintiffs’ suggestion that 

ASTM F2508 cannot be used to determine the reasonable safety of a walking surface. See id. at 

11–13. According to CVS, ASTM F2508 “does not purport to establish what does and what does 

not constitute a safe walking surface.” Id. at 12. Instead, it “is a control that governs the . . . 

operation of tribometers to be able to accurately measure the COF value, which, in turn, can be 

used to evaluate the safety of a walkway surface.” Id. at 13 (internal quotation marks omitted). 

CVS also argues that the studies upon which Plaintiffs rely to assert that VIT testing is 

unreliable merely recommend that slip resistance measurements account for variability, as 

Maddox’s measurements did. Id. at 18–19. With respect to the Plaintiffs’ argument about ASTM 

F1679’s withdrawal, CVS notes that Maddox did not rely on this standard and that a federal court 

rejected this argument in ruling that VIT testing is reliable. Id. at 20–21. CVS also asserts, 

contrary to the Plaintiffs’ suggestion, that the manufacturer of Maddox’s VIT calibrated the device 

three days before Maddox’s field test and that Maddox herself field calibrated the same device the 

day before her field test. Id. at 13–14. Further, CVS argues that Maddox performed her testing 

according to the specifications of the VIT manual and her training, yielding “reliable” and 

“reproducible” results. Id. at 15. More generally, CVS argues that Plaintiffs’ attack on Maddox’s 

conclusions “is more properly characterized as cross-examination material” and “is not a proper 

basis to seek to exclude her opinions under Rule 702 and/or Daubert.” Id. at 21.

Maddox’s VIT testing meets the threshold reliability requirements under Rule 702 and 

Daubert. Federal courts have often denied Rule 702 motions challenging the reliability of VIT 
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testing. See, e.g., Barnes, 320 F.R.D. at 139; Piazza, 2022 WL 16923867, at *1–2; Darby, 2021 

WL 6428039, at *10; Armas, 2022 WL 17982239, at *5; Feuerstein, 2014 WL 2616582, at *3; 

Atkinson, 2021 WL 8534238, at *4; Steffen, 2014 WL 1494108, at *6. Further, Maddox used an 

ASTM F2508-validated VIT, which strengthens the reliability of her methodology. ECF No. 33-

5 at 14; see Armas, 2022 WL 17982239, at *5. Indeed, Maddox’s methodology appears to be even 

more reliable than the expert’s methodology in Barnes, in which the court denied a Rule 702 

motion despite acknowledging that “the Court is concerned that [the expert] did not use the 

tribometer as the manufacturer intended” and that the expert “was not certain when the device had 

been calibrated.” 320 F.R.D. at 139. Here, in contrast, Maddox performed her testing in 

accordance with the manufacturer’s manual, and both the manufacturer and Maddox calibrated the 

VIT within three days of the field test. ECF No. 33-5 at 9; ECF No. 49-4 at 3, Ex. 6 at 18–21. 

Significantly, Plaintiffs do not identify any instance in which a federal court has found VIT

testing to be an unreliable methodology. To be sure, Plaintiffs do identify one state court case in 

which the court excluded an expert’s VIT test results. Britz v. Aria Resort & Casino, No. A-18-

770380-C, 2020 Nev. Dist. LEXIS 111, at *4 (Jan. 31, 2020). In that case, however, the court 

provided no explanation or analysis beyond its conclusion that ANSI A1264.2 “is not a standard 

but a recommendation” and that English XL testing “is not published or peer-reviewed.” Id. 

Without more, this state court decision is insufficient to overcome the extensive federal decisions 

rejecting Rule 702 challenges to the reliability of VIT testing. 

The various arguments Plaintiffs make regarding VIT testing go to the weight of the 

evidence, not its admissibility. Once a court determines that an expert is qualified under Rule 702, 

it “assumes only a limited gate-keeping role directed at excluding expert testimony that is based 

upon subjective belief or unsupported speculation.” Heller, 952 F. Supp. 2d at 140 (internal 
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quotation marks omitted). In this Circuit, expert testimony is not reliable when it is based on 

“guesswork, speculation, and conjecture.” Joy, 999 F.2d at 568. 

Plaintiffs’ argument that Maddox’s reliance on ASTM F2508 renders her methodology 

unreliable is not persuasive. As noted above, federal courts have consistently ruled that VIT testing 

is reliable, including when the VIT is validated by ASTM F2508. E.g., Darby, 2021 WL 6428039, 

at *10, adopted by, 2022 WL 112193; Armas, 2022 WL 17982239, at *5. Moreover, ASTM F2508 

is an “international standard” that is “intended to establish the procedures for validation, 

calibration, and certification of [VITs].” ECF 45-4 at 1. Maddox, therefore, relied on a standard 

that is intended to control the operation of VITs, which weighs in favor of reliability under 

Daubert. 509 U.S. at 594 (directing courts to consider “the existence and maintenance of standards 

controlling the technique’s operation” when evaluating the reliability of a scientific technique). 

Even if the Court were to accept the Plaintiffs’ assertions that ASTM F2508 is “based on an 

unrepresentative sample of humans that are nothing like Dr. Bunting,” it cannot be said that 

Maddox’s testimony is “based upon subjective belief or unsupported speculation.” ECF No. 45-1 

at 11–12; Heller, 952 F. Supp. 2d at 140. 

Similarly, the studies and publications upon which Plaintiffs rely to raise concerns about 

VIT testing do not support excluding Maddox’s testimony. These sources discuss the need to 

consider measurement uncertainty when interpreting VIT testing results. See, e.g., ECF No. 45-5 

at 1; ECF No. 45-6 at 12. As CVS points out, however, Maddox accounted for uncertainty by 

testing the surface at different locations and presenting the slip index values as “mean ± standard 

deviation.” ECF No. 45-1 at 12–14; ECF No. 49 at 19; ECF No. 33-5 at 9. To the extent that 

Plaintiffs disagree with the extent to which Maddox accounted for uncertainty in her conclusions, 
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Plaintiffs can address this issue through “vigorous cross-examination, presentation of contrary 

evidence, and careful instruction on the burden of proof.” Daubert, 509 U.S. at 596. 

Plaintiffs’ remaining arguments are unpersuasive. Plaintiffs argue that ASTM’s decision 

in 2006 to withdraw ASTM F1679 renders Maddox’s testing unreliable, but Maddox did not rely 

on ASTM F1679 in her report. ECF No. 45-1 at 14–16. Indeed, Plaintiffs do not suggest that any 

of the standards upon which Maddox relies have been withdrawn. Finally, Plaintiffs assert that 

Maddox “failed to demonstrate that she had calibrated her [VIT] correctly,” but as discussed above, 

the manufacturer calibrated Maddox’s VIT three days before the field test and then Maddox field 

calibrated her VIT the day before the field test. Id. at 16; ECF No. 33-5 at 6. Any potential 

deficiencies in how the manufacturer or Maddox calibrated the VIT go to the weight of the 

evidence, not its admissibility. See Daubert, 509 U.S. at 596. 

CONCLUSION

For the foregoing reasons, the Court DENIES Plaintiffs’ Motion, ECF No. 45. A separate 

order will issue.

SO ORDERED. 

Date: February 7, 2024 

____________________________________ 

MOXILA A. UPADHYAYA

 UNITED STATES MAGISTRATE JUDGE