Court addresses Daubert challenges filed against both the Plaintiffs' and Defendants' expert witnesses amidst claims of premises liability and product liability

Court addresses Daubert challenges filed against both the Plaintiffs’ and Defendants’ expert witnesses amidst claims of premises liability and product liability

Valerie Koger, a Costco member, visited the Costco store in Fremont, California, on November 1, 2018, seeking dining chairs. While browsing, she encountered a Stakmore wooden folding chair displayed on an aisle. Upon sitting on it, the chair immediately collapsed, causing her to fall to the ground. The impact from the chair’s failure resulted in a severe blow to her head, akin to being struck with a baseball bat, leading to a diagnosis of a mild head injury at Washington Hospital on the day of the incident. Her symptoms escalated, and within two days, she was diagnosed with dizziness, vertigo, and post-concussion vertigo.

The Stakmore wooden folding chair in question was exclusively designed and provided by Meco for Costco in 2018. Costco had directly procured the chair from Meco, a supplier and vendor for the retail chain. Valerie Koger, alongside Jeffrey Koger, filed claims against Costco Wholesale Corporation and Costco Wholesale Membership, Inc., asserting premises liability due to the hazardous furniture display. Additionally, they pursued product liability claims against all involved parties, including Meco Corporation, citing the defective nature of the chair.

The Plaintiff initiated Daubert motions against three experts enlisted by the Defendant: Jon B. Ver Halen, Eric J. Drabkin, and Stephen D. Forner. In response, the Defendant countered by filing Daubert motions against three of the Plaintiff’s experts: Zachary M. Moore, Leonard J. Backer, and Mark D’Esposito.

Premises Liability Expert Witnesses

Jon B. Ver Halen holds an Industrial Engineering degree from Purdue University. He has 32 years of experience as President of Ver Halen Engineering, a small consulting firm specializing in facilities design, manufacturing processes, product safety assessments, and expert witness testimony related to the aforementioned specialities. Jon Halen has been qualified as an expert engineer in over 30 states and provided expert testimony in hundreds of legal cases. 

Zachary M. Moore holds a Bachelor of Science degree in Mechanical Engineering from Loyola Marymount University. He is a licensed Professional Mechanical Engineer in California. He is currently a Forensic Engineer with Aperture, LLC. Moore is also a Board-Certified Diplomate in Forensic Engineering and a Certified XL Tribometrist. He has over 18 years of experience investigating premises liability cases and testifying as a forensic engineering expert in numerous litigation cases. 

Leonard J. Backer holds a B.A. degree from Rutgers University. He has over 30 years of relevant work experience, including officer-level roles at multiple furniture companies. Backer currently serves as President of Leonard J. Backer Associates LLC, where he works as a furniture expert witness and consultant since 2008. He is certified as an expert witness in many state and federal courts. 

Causation Expert Witnesses

Stephen D. Forner holds a B.A. in Chemistry and Physics from George Washington University and an M.D. from the University of Pennsylvania School of Medicine. He completed his neurology residency at Stanford University School of Medicine and his fellowship in clinical neurophysiology at the University of Texas Southwestern Medical School. Forner currently maintains his private practice at Kings Beach, California. He has previously worked at the Tahoe Forest Hospital Multispecialty Clinic and as a Clinical Professor of Neurology at the UC Davis School of Medicine.

Mark D’Esposito holds a B.S. in Neuroscience and B.A. in Interdisciplinary Studies from the University of Rochester. He obtained his M.D. from SUNY Health Science Center, College of Medicine. D’Esposito completed his residency and his fellowships at Boston University Medical Center. He is certified by the American Board of Psychiatry and Neurology. He is currently a Distinguished Professor of Neuroscience and Psychology at the University of California, Berkeley. He also serves as a staff neurologist at Northern California VA Health Care System’s Cognitive Neurology and Stroke Clinic.  

Damages Expert Witness

Eric J. Drabkin holds a Ph.D. and an M.A. in Economics from the University of California, Los Angeles. He has a Diploma in Economics from the London School of Economics, and a B.A. in Economics from the University of California, Berkeley. Drabkin is currently a Senior Vice President of Forensic Accounting & Economics at J.S. Held. He has previously worked as a Senior Consulting Economist at Cohen Volk Economic Consulting Group and a Managing Director at Berkeley Research Group.   

Discussion by the Court

The Plaintiff contested three specific opinions presented by the Defendant’s expert, Jon B. Ver Halen under Rule 702 and Daubert :

  • Ver Halen asserted that the design of the subject chair was reasonably safe and met appropriate standards, asserting its capability to support over 300 pounds safely.
  • Ver Halen suggested that the wood screws attaching the folding brackets to the front spreader failed due to the application of excessive force. He also claimed that the splintering observed at the screw holes indicated the presence of sound wood.
  • Ver Halen posited that the wood screws securing the folding brackets to the front spreader couldn’t have failed under normal use of the chair.

Plaintiff alleged that he did not consider all relevant evidence; his first opinion was based on inadmissible SGS testing; and his three opinions were based on independent testing employing unreliable methodology.

The Court held that expert testimony relying on undisclosed or poorly described methodology must be excluded, because opinions based on “unsubstantiated and undocumented information is the antithesis of . . . scientifically reliable expert opinion”, citing Cabrera v. Cordis Corporation, 134 F.3d 1418 (9th Cir. 1998).

Ver Halen, in his Expert Report’s third page, incorporated a section titled “Testing by SGS,” which indicated that an independent testing entity, SGS, conducted assessments on the chair design, affirming that the chair successfully passed all required tests. Ver Halen relied on these test “results” to form the foundation for his initial opinion that “the design of the subject chair is reasonably safe and meets the appropriate standards.”

However, the Court determined that Ver Halen merely restated the conclusions derived from the SGS tests without delving into their underlying data or methodology. The Court highlighted that experts aren’t allowed to repackage inadmissible hearsay as expert testimony.

To render opinions regarding why the chair failed in this case, Ver Halen performed “testing” on a Stakmore chair he found in his breakroom. Ver Halen’s report, spanning less than four pages, lacked the necessary details to reproduce his findings or to fairly assess his conclusions. His testing procedure involved three tests:

  • The first test focused on the coefficient of friction for the gliders beneath the chair legs, aiming to determine if the chair legs could shoot forward as experienced by Koger in the absence of screws. Ver Halen concluded that the results supported the possibility of the collapse occurring as described by Koger.
  • The second test involved opening and closing the chair a few times to verify if damage was likely to occur to the front bracket and screw assembly during normal usage.
  • The third test entailed placing the chair on its back, standing on the back legs, and using a pressure gauge to measure the force required to dislodge the front bracket and screw assembly when pulling up on the front legs individually.

Ver Halen’s testing methods lacked comprehensive detail and relied on an exemplar chair of uncertain origin, undermining the credibility of the results. Defendants argued that Ver Halen’s testing adhered to scientific rigor, physics principles, Business and Institutional Furniture Manufacturers Association (BIFMA) standards, and “sound economic methodologies.” Yet, apart from the coefficient of friction tests, Court held that Ver Halen’s report lacked discussions on physics, BIFMA standards, or other concepts supporting his conclusions.

Ultimately, the Court ruled that Ver Halen would not be permitted to offer opinions based on either the SGS testing or his independent testing due to the insufficiency and lack of thoroughness in his report.

The Defendants jointly relied on the expert opinions of Eric J. Drabkin to assess the economic losses incurred by the Plaintiffs in the case. Drabkin’s assessment suggested that, had the injury not occurred, Koger would have only worked an additional 4.75 years. The Plaintiff contested Drabkin’s reliance on Craig A. Allen’s article, titled “Labor Force Transitions by Gender: Implications for Separate and Combined Worklife Expectancy,” published in the Journal of Forensic Economics. This challenge was based on California Civil Code section 3361, which prohibits experts from relying on studies and statistics considering race, ethnicity, or gender in wage and earnings predictions.

Koger, employed as a school bus driver for the Fremont Unified School District, was driving special needs students to and from school at the time she was injured. Despite the article’s title, the Court found that the underlying data on which Drabkin relied did not make gender-based predictions but provided weighted averages based solely on age and educational attainment.

The Plaintiffs argued that the article’s analysis of Table 1 demonstrated gender-based predictions, but the Court found this argument misleading. The article applied gender-agnostic estimates to both male and female populations, resulting in slightly lower worklife expectancies for women on average. However, these differences were attributed to variations in education levels and workforce participation between men and women. Importantly, the gender-agnostic estimates in Table 1 would not reduce damage estimates based solely on plaintiff Koger’s gender. Consequently, the Plaintiffs’ request to exclude Drabkin’s opinions was denied by the Court.

The Plaintiffs sought to prevent Stephen D. Forner from proposing alternative explanations for Koger’s symptoms in the case. Forner’s expert report concluded that Koger likely didn’t suffer a traumatic brain injury due to the incident but instead suggested that her symptoms might be partially explained by functional neurologic disorder (FND) or benign paroxysmal positional vertigo (BPPV). Notably, Forner didn’t explicitly diagnose Koger with either FND or BPPV but indicated that these conditions should be considered as potential partial explanations, acknowledging that they might not account for all her reported symptoms.

The Plaintiffs objected to Forner’s refusal to definitively diagnose Koger with FND or BPPV. However, the Plaintiffs failed to reference any binding or persuasive case mandating that when a clinician dismisses a diagnosis, they must propose an alternative diagnosis. The Court found Forner’s reluctance to diagnose as reasonable. Forner encountered instances where he lacked crucial medical records or further information from key neurological evaluations. Additionally, in some cases, tests were conducted, but the results were unavailable. Given the incomplete medical records, the Court deemed Forner’s cautious approach and the level of confidence in his assessment of Koger’s condition as appropriate.

Now coming to the Daubert motions filed by the Defendants, Defendants first sought to exclude Zachary M. Moore from presenting legal conclusions as expert opinion.

The Court addressed multiple opinions presented by Moore, an expert witness in the case:

  1. Moore’s first opinion, asserting that the chair was unsafe at the time of the incident, was deemed an unadorned legal conclusion. The Court ruled that Moore, lacking expertise in product design or consumer safety, couldn’t testify about the chair’s safety or Koger’s actions in a legal context.
  2. Moore’s second opinion, contending that the subject location violated codes and industry standards, was considered inappropriate due to insufficiently supported references to industry standards. Moore’s brief mention of industry standards lacked analysis and relied solely on language from an insurance company manual. Consequently, the Court disallowed this opinion from being presented at trial.
  3. Moore’s third opinion, suggesting that Costco knew or should have known about the unsafe condition, was grounded on a more robust factual and methodological basis. Moore’s analysis of employee testimony and Costco’s inspection policies led to the conclusion that employees failed to adhere to the company’s policies. The Court permitted Moore’s testimony within factual confines, as long as it refrained from purely legal conclusions.
  4. Moore’s fourth opinion, claiming that the cost to eliminate the unsafe condition would have been minimal, was excluded by the Court. His statement about Costco’s potential implementation of an adequate inspection policy lacked substantiation and analysis regarding the policy’s nature or the estimated costs involved. Therefore, the Court barred this opinion from being presented in the case.

The Defendants next sought to exclude certain opinions presented by Leonard J. Backer, contending that he lacked qualifications to opine on Costco’s failure to inspect the store premises or that these opinions constituted impermissible legal conclusions.

Backer, specializing in the design, manufacture, and sale of chairs, claimed expertise in “retail store planning markets,” encompassing “visual merchandising” related to chairs. However, there was no demonstrated experience in premises safety or the inspection and risk management standards applicable to retail stores within his record. Backer’s report contained opinions regarding Costco’s responsibility for maintaining premises safety and its inspection procedures, topics beyond his field of expertise and unrelated to chairs or his area of knowledge.

The Court ruled that Backer would not be allowed to testify regarding Costco’s safety or inspection procedures due to his lack of expertise or relevance to the subject matter.

Defendants sought to exclude Mark D’Esposito from testifying based on their assertion that he conducted a VOMS (Vestibular/Ocular Motor Screening) test on Koger. However, Plaintiffs objected, stating that D’Esposito didn’t perform a VOMS test. Nevertheless, even if a VOMS test had been conducted, plaintiffs argued it would have been appropriate.

D’Esposito asserted that he conducted a thorough review of Koger’s medical records and administered a comprehensive neurological examination that involved at least seven neurological tests. While some of these tests overlap with those in a VOMS screening, they are also commonly associated with neurological assessments beyond the scope of athletic events. There’s no indication that tests used in a VOMS context are exclusively valid only within that context.

The Court acknowledged that even if D’Esposito had performed a VOMS test on Koger, it wouldn’t warrant exclusion. Defendants conceded that the method itself is used to diagnose specific head injuries, which doesn’t fall under the “junk science” category prohibited by Rule 702. Whether these testing methods were suitable for Koger’s circumstances would be a matter for cross-examination rather than justification for exclusion.


  • The Court granted the Plaintiff’s motion to exclude, in part, the testimony of Defendant’s expert Jon B. Ver Halen.
  • The Court denied the Plaintiff’s motion to exclude, in part, the testimony of Defendant’s expert Eric J. Drabkin.
  • The Court denied the Plaintiff’s motion to exclude, in part, the testimony of Defendant’s expert Stephen D. Forner.
  • The Court granted in part and denied in part the Defendant’s motion to exclude the opinions of Plaintiff’s expert Zachary M. Moore.
  • The Court granted the Defendant’s motion to exclude some of the opinions of Plaintiff’s expert Leonard J. Backer.
  • The Court denied the Defendant’s motion to exclude the opinions of Plaintiff’s expert Mark D’Esposito related to VOMS test and results.

Key Takeaways:

  1. An expert’s testing methods must be reliable and described in enough detail to allow independent validation. Vague descriptions or undisclosed methodologies will lead to exclusion.
  2. Experts cannot present legal conclusions or opine on the law, but may testify about industry standards if properly supported. Conclusions that invade the province of the fact finder will be excluded.
  3. Experts should not testify beyond their expertise. For example, with expertise in the design, manufacture, and sale of chairs, one cannot opine on store safety procedures and inspection policies.
  4. Alternative medical explanations suggested by an expert need not be definitive diagnoses. If records are incomplete, limited confidence in assessing conditions is reasonable.
  5. Use of testing methods outside their common context is not necessarily grounds for exclusion if the methods may help diagnose conditions. Attacks should target appropriateness of specific application.