The Expert: Dr. Thomas McNish, a physician and bioengineering expert, testifies for the defense.
Testifying in a 2017 product liability trial out of West Virginia, Dr. Thomas McNish, a physician and bioengineering expert, gives his opinion regarding the plaintiff’s claim that a defect in a 1999 Subaru Forester caused a fire that killed 3 people in a head-on crash.
Pivotal to the doctor’s theory that a crash-related fire did not kill the 3 people is his explanation of how the seat belt in a car works. As pressure is placed on the shoulder harness, the lap belt tightens because it goes through the latch plate’s pass-through. If a person neglects to position the shoulder harness appropriately across their chest, and instead places it behind them, the lap belt will permit about 5 inches of forward movement of the lower body on impact. The upper body, having no restraint, will travel farther forward as well.
Turning to the case at issue, the first people to arrive at the scene of the accident reported that they did not see a shoulder harness on the victim in question. Her upper torso was partly extruded from the window as she was either thrown, or attempted to get herself out of the car with the seatbelt still locked in place. With the shoulder restraint not properly in place, and the passenger unable to use her legs because of two broken femurs, her upper body had come to rest in an awkward position partially out of the right rear window. This fact hindered witnesses from getting her out.
Using full-size pictures of a vehicle cabin with a surrogate passenger placed in the right back seat, McNish demonstrates the positioning and resultant displacement of the crash victim under consideration. The vehicle in this case had come to rest at a forty degree downward angle on the shoulder of the highway. He uses this position to show that, even without impact, the woman in the back seat would have come forward about five inches, crushing her knees into the lower part of the front seat. Her unrestrained upper torso would have used the back of the right front seat “as her airbag” to stop her forward momentum. In this position, even the surrogate had a great deal of difficulty in reaching back to unlatch the seat belt to allow her to exit the vehicle. This demonstration supports the expert’s conclusion that the victim in the right back seat had placed the shoulder restraint behind her back, rather than across her chest as intended.
McNish further reconstructs the events with easily understood diagrams. First he shows that the impact from a head-on collision with a total force of 50 miles per hour would be equivalent to dropping the vehicle 80 feet, or from the roof of an eight-story building, straight down onto its nose. This gives the jury perspective of the magnitude of the vehicle’s deceleration in the collision.
Then he demonstrates the sequence of events and the resultant change in positioning of a passenger sitting where this woman was. First he explores how the position changes on impact for a person wearing the seat belt properly. The knees do not impact with the front seat enough to move it forward, and the head escapes impact altogether. When the car comes to rest on the sloped embankment, the passenger is held in place against the rear seat by the shoulder harness, and the upper torso does not hang out of the right rear window.
With the shoulder harness routed instead around the back, the kinematic studies demonstrate the victim’s knees forcefully pushing the front seat forward from the rear, and her head slamming into the front head rest. Post-crash, the illustrations demonstrate shortening of the victim’s legs due to fractures, and the head resting out of the right rear window.
McNish continues, using demonstratives to compare what happens with a passenger in the front seat properly restrained with one in the seat behind her that has decided to fasten in with the shoulder restraint behind her back. He describes that, on impact, the front seat passenger’s head is buttressed by the air bag while her hips and back remain pressed into the seat. However the back passenger’s knees press deeply enough into the back seat to cause significant damage to the back of the front rider held in place, while the head and arms of the rear passenger push forward on the front seat, adding to the momentum of the chest and abdomen of the front passenger. In this case, damage to the front passenger in these areas was confirmed on autopsy.
Given this severity and his certainty that the rear passenger had the shoulder restraint latched in behind her back, Dr. McNish concludes that the crash itself caused the victims’ demise regardless of the fire that resulted.
His testimony was convincing, as the jury returned a verdict for the defense.
Gary Gansar, MD, is residency-trained in general surgery. He served as Chief of Surgery and Staff at Elmwood Medical Center and on the Medical Executive Committee at Touro Infirmary and Mercy Hospital in New Orleans, LA. Dr. Gansar was Board Certified in general surgery while in active practice. He joined AMFS in 2015 as a Physician Medical Director.
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