Expert Testimony on Crash Reconstruction Limited

Court limits expert testimony on crash reconstruction and its contributing factors

This case arises from a car accident that occurred on October 8, 2021 in San Antonio, Texas. Plaintiff Lesley Aguilar was a passenger in a vehicle driven by Defendant Hector Collazo-Diaz. Collazo-Diaz worked as a delivery driver for Defendant DoorDash at the time. He was traveling westbound on Rittiman Road and approached an intersection with IH 35 N Access Road. At the same time, a third party driver David Hidalgo was traveling northbound on the access road. Hidalgo had the right of way to proceed through the intersection. As Hidalgo entered the intersection, Collazo-Diaz failed to yield the right of way and collided with Hidalgo’s vehicle, causing injuries to Aguilar.  

Aguilar filed a negligence lawsuit against Collazo-Diaz and DoorDash in June 2022. She alleged that DoorDash was vicariously liable for Collazo-Diaz’s negligence either as his employer or as a joint venture partner. Aguilar also brought direct negligence claims against DoorDash for negligent hiring, training, and supervision of Collazo-Diaz. 

Aguilar designated Leonard Vaughan as an expert witness to reconstruct the accident and opine on factors that contributed to it, including alleged traffic violations by Collazo-Diaz. Vaughan had over 50 years of experience in accident reconstruction. He reviewed the accident scene, crash photographs, deposition testimony, and the police report.  

After inspecting the accident scene, analyzing crash photographs, reviewing applicable deposition testimony, and evaluating the San Antonio Police Department crash file, Vaughan produced a report expressing the following opinions:

  1. David Hidalgo was driving his 2014 Chevrolet Equinox on the northbound access round of IH-35 as he approached the site of the incident.
  2. According to the police report, Hidalgo stopped at the intersection before crossing Rittman Road.
  3. Hector Collazo-Diaz was driving his 2020 Mitsubishi Eclipse on [sic] westbound Rittman Road as he approached the site of the incident.
  4. Collazo-Diaz slowed down but did not stop at the intersection.
  5. Collazo-Diaz stated in his interrogatory response that there was a power outage at the time of the incident.
  6. Collazo-Diaz testified that he was traveling at the speed limit of 35 approaching the intersection.
  7. As Collazo-Diaz approached the intersection, the headlights of the Chevy Equinox would have been visible entering the intersection to Collazo-Diaz’ [sic] left.
  8. Collazo-Diaz stated that after slowing to 25-30, he proceeded forward without stopping because he didn’t see a reason to stop.
  9. Collazo-Diaz stated that he knows that when traffic lights are not operational, a motorist is supposed to treat the intersection like a 4-way stop.
  10. Collazo-Diaz stated that he did not see the traffic lights because they were obscured by the overpass behind the traffic lights.
  11. Collazo-Diaz also stated that he did not know he was approaching a major intersection, thinking instead that it looked like an exit from the overpass.
  12. Collazo-Diaz should have stopped his vehicle enough to accurately assess the safety of moving through [sic] intersection.
  13. DoorDash, through their driver Hector Collazo-Diaz, violated Texas Transportation Code when Collazo-Diaz failed to appropriately reduce his speed as he approached this collision.

DoorDash argued that several of Vaughan’s Opinions 1-6 and 8-11 were essentially restatements of uncontested facts, contending that these should have been presented to the jury through fact witnesses rather than expert testimony. Furthermore, DoorDash claimed that Opinions 7, 12, and 13 which were related to visibility, duty, and liability, lacked a solid factual foundation and were speculative. They also asserted that Vaughan’s opinions failed to meet the requirements of Rule 403, potentially causing confusion or prejudice that outweighed their value. Lastly, DoorDash objected to Vaughan’s opinion on vicarious liability, asserting that it went beyond his expertise.

DoorDash moved to exclude Vaughan’s testimony in full. It argued the factual recitations were not expert opinions and invaded the jury’s role. It also contended Opinions 7, 12 and 13 were unreliable speculation, impermissible legal conclusions, and should be excluded under Rule 403. 

Accident Reconstruction Expert Witness 

Leonard D. Vaughan has a Bachelor of Science degree in Law Enforcement and attended the Texas Department of Public Safety Training Academy. Vaughan was an instructor of accident investigation and reconstruction and advanced accident reconstruction at the Middle Rio Grande Law Enforcement Training Academy from 1979 through 1986. He was also an instructor of accident reconstruction from 1979 through 1986 at the Texas Department of Public Safety Training Academy and advanced accident investigation and reconstruction from 1983 through 2004 with the Texas Department of Public Safety. In 1993, Leonard Vaughan received the Director’s Award from the Texas Department of Public Safety. Vaughan has been a charter member of the International Association of Accident Reconstruction Specialists.


Discussions by the Court 

The Court first discussed Leonard Vaughan’s qualifications as an accident reconstruction expert. It noted that under Rule 702 and Fifth Circuit precedent, the key factors for determining expert qualifications include professional rank, teaching courses taught by the proposed expert, degrees/certificates, certification by professional associations, whether the proposed expert has been excluded by other courts, conducting studies, taking measurements and collecting data, relying solely on public data, and maintaining expertise. The Court found that Vaughan’s long career, accident reconstruction certificates, teaching experience, and membership in a professional association satisfied these requirements. Thus, the Court was assured Vaughan was qualified as an expert.  

Next, the Court addressed DoorDash’s argument that Vaughan’s factual recitations were not true expert opinions and invaded the jury’s role. The Court recognized the risk of an expert merely summarizing facts the jury could understand itself. However, it noted experts were permitted to make assumptions based on facts in the record. Vaughan drew selectively on the record when making assumptions underlying his opinions. As long as the facts were the type accident reconstruction experts rely on, Vaughan could base opinions on them. His recitation of facts did not constitute a credibility determination. Any disputes about his factual assumptions could be addressed through cross-examination and contrary evidence at trial. Thus, the Court found the factual opinions admissible. 

The Court then turned to the reliability of Vaughan’s opinions on the visibility of Hidalgo’s headlights and Collazo-Diaz’s duty to fully stop at the intersection. DoorDash argued these lacked scientific methodology because Vaughan did not take measurements, analyze vehicle data, interview the drivers, etc. It claimed his analysis was similar to the excluded expert in another case who relied solely on photos and “common sense.” The Court found Vaughan’s review of photos, the scene, maps, and depositions was sufficiently reliable methodology given his experience  for the purpose of admitting his opinion as to the visibility of Hidalgo’s headlights (Opinion 7). The facts relied upon went to the weight, not admissibility, of his testimony. The visibility opinion was also relevant and not unduly prejudicial under Rule 403. 

However, the Court agreed with DoorDash that Vaughan’s opinions on Collazo-Diaz’s duty to stop and DoorDash’s vicarious liability were impermissible legal conclusions. Vaughan lacked expertise to opine on vicarious liability based on the employment relationship considering that whether a worker is an employee or an independent contractor depended on “whether the employer has the right to control the progress, details, and methods of operations of the work” as was held in Painter v. Amerimex Drilling I, Ltd. More importantly, his conclusions on the proper standard of care, breach, and vicarious liability invaded the Court’s and jury’s roles. Experts cannot offer legal opinions or instruct on applying law to facts. Thus, the Court granted the motion to exclude the legal conclusions, while denying it as to the rest of Vaughan’s opinions. 


In conclusion, the Court granted DoorDash’s motion as to the legal conclusions in Opinions 12-13. It otherwise denied the motion without prejudice to DoorDash raising objections at trial. Vaughan may testify, but certain aspects of his opinions were questionable. His testimony could be excluded or discounted as unreliable depending on the trial evidence. 

The Court has not arrived on an outcome for this case since the remaining issues involved in this case still await resolution.

Key Takeaways 

This case illustrates the importance of scrutinizing expert qualifications and preventing experts from offering legal conclusions. The Court demonstrated its gatekeeping role under Daubert by thoroughly assessing accident reconstructionist Leonard Vaughan’s credentials before allowing his testimony. His extensive experience satisfied the key qualification factors.  

The Court also emphasized that experts may make assumptions based on facts in the record, but those assumptions must have evidentiary support. Critically examining an expert’s factual basis is key.  

However, the Court enforced the principle that experts cannot provide legal conclusions. Vaughan’s opinions on the proper standard of care and vicarious liability were impermissible legal conclusions that usurped the Court and jury’s authority. Although experts can opine on ultimate issues, they cannot instruct on how the law applies or offer opinions on legal questions. 

In summary, this case highlights the need to qualify experts, vet their methodologies and assumptions, and preclude legal opinions. Vigorous cross-examination at trial can address shaky expert opinions, but courts must act as gatekeepers and exclude testimony invading the legal province. Careful scrutiny of expert foundations, reasoning and conclusions is crucial. 


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