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Do You Need a Biomechanics Expert? If so, How Do You Use One

by Steven Gursten, Michigan Auto Law

You receive a phone call from a person who was injured in an auto accident. The prospective client reports he was rear-ended in a recent motor vehicle crash. He is complaining of severe pain in his neck and back. You sign the case. You also order the police report.

The Police Report arrives shortly after. It indicates a 0 out of a possible 7 for vehicle crash severity, which is the lowest possible score. The vehicle was noted to be driveable at the scene. Photographs of the vehicle damage reveal barely anything at all. It is what the insurance company calls a minor impact, minimal property damage case. You know juries don’t like these cases either, so you try to settle the case by sending a demand letter.

The liability carrier makes a very low settlement offer.

You file suit.

The defense takes a hardline settlement position based upon vehicle damage. When you receive the defendant’s witness list and note that they have hired a biomechanical engineer to help them defend the case.

You start to wonder what you’ve gotten yourself into.

A few months later you receive the Defendant’s biomechanical expert’s report. This expert opines that the forces experienced by your client in this crash were the equivalent of “flopping down on a chair” or “stepping down from a short stool.” The opinion is delivered with strong flair and indicates that upon reviewing the property damage photos and perhaps a few calculations, that it is virtually impossible for your client to have suffered the injuries he is now claiming from this motor vehicle crash.

What do you do?

The knee-jerk reaction of most lawyers is to out and hire your own biomechanical engineer. But a biomechanical engineer can cost $25,000-$50,000. What auto lawyers should do instead is to carefully consider the reasons why you would want a biomechanical expert on your case. Unless you have a corporate defendant or have sufficiently large policy limits, the cost and expenses of the biomechanical expert can quickly escalate past the point where it becomes cost effective to hire one.

What are the issues that you seek to prove with the expert – and is the biomechanical engineer the only way you can do this? Will the biomechanical expert’s testimony provide a critical and important bridge between the crash and your client’s injuries, or is it (more likely) the result of panicking after seeing the Defendant’s expert report.

Before you hire a biomechanical expert of your own, consider whether your purpose can be achieved in a far more direct and efficient – as well as cheaper – manner.

This fight is usually best won in a gatekeeper evidentiary hearing.

Fortunately, evidentiary hearings to exclude defense biomechanical engineers have been won across the country. In Michigan, where I primarily practice auto crash litigation, I’ve personally struck 2 biomechanical engineers from testifying in my cases. When I see that a defendant has listed a biomechanical expert on their witness list these days, I write pick up the phone and let the defense lawyer know that they are going to spend a ton of money and this expert will most likely never testify. I also write a letter to him stating the same that the defense lawyer can forward on to the claims adjuster.

I almost always receive a response back from the defense lawyer that they have decided not to use the expert.
If you do decide you have the right case to hire your own biomechanical engineer, the critical distinction between a plaintiff biomechanical engineer and a defense biomechanical engineer is this: A plaintiff biomechanical engineer can properly testify only that the forces involved in a crash were sufficient to cause an injury. Notice that the plaintiff biomechanical engineer is not saying that the forces involved did cause your client’s injury.

The defense biomechanical engineer, in contrast, is making such a conclusion. The defense biomechanical engineer is saying that it is impossible that the forces involved could have caused your client’s injuries. The expert is basing this conclusion on a generalization. And therein lies the key to striking this expert. The essential flaw with this testimony is that it attempts to apply a scientific correlation between property damage and the injury potential of a population, but not to your client as a specific individual. As long as the defendant biomechanical engineer admits that it is at least possible that your client has sustained an injury in this crash, then the rest of his opinion is a guess based upon the probability of injury to a population, such as of 21 year old male air force volunteers, and not to your client. It is speculation. Expert opinion based upon speculation is not admissible. The opinion as it applies to your specific client as an individual is unsupported and does not take into account all the unique ways your client is different, and perhaps more susceptible, to being severely injured in a low impact crash. These opinions are not based upon medical examination of your client and do not take into account your client’s height, weight, gender, age, susceptibility, pre-existing injuries, etc. These opinions are non-specific to the types of vehicles involved in the impact. It is non-specific to your client’s body position and how she was sitting in the vehicle. It is non-specific as to where her headrest position was, her seat position, how she was holding the steering wheel. It is speculation based upon a gross generalization of the potential for injury based upon the likelihood of possible injury to the general population, but not to your client.

But when it applies to your client, there can be no meaningful relationship between property damage and injury potential to a general population. This is the fatal flaw that has led to expert defense biomechanical testimony being struck in cases and courtrooms across the country..
The underlying speculation of these opinions can be further demonstrated by having the defense expert agree, as he or she must, that people have been severely injured and even killed in very low damage motor vehicle crashes.

Once the defendant biomechanical expert admits, as they must, that it is at least possible for your client to have been injured, the testimony must be struck because the rest of it is just guessing whether your client falls within an unscientific generalization about the potential for injury of a general population of people. There is almost never a medical examination done of your client to support the biomechanical engineers, so it remains in the end an unscientific guess that takes none of the factors that make your client unique and different from a given group of people into account.

In any specific car crash there can be no meaningful relationship between property damage and injury potential. It is unknown whether an individual in question will be one of perhaps 1% or 5% of a population who will be injured – until after the fact when that individual has already sustained injury.

Therefore, the injury potential of an impact or crash can only be made after your client has in fact been injured. It is based only on the medical evidence, temporal relationship to the crash, and clinical correlation based upon medical treatment for your client. That is the gold standard on medical causation that doctors are taught in medical school. It’s why a neurosurgeon or a hospital emergency room doesn’t ask to see the pictures of the car the person was driving in when they are rendering treatment.

As one well-respected trauma epidemiologist says, it is no different than arguing that because there is only a 1 in 1 million chance of someone ever dying in a plane crash, that it is therefore impossible to die in a plane crash.

The rather paltry scientific papers that these Defendant biomechanical engineers rely upon can never be used to show that it is impossible to be hurt in an identical crash. All these papers show is that it is possible not to be hurt. Crash test studies of a dozen or two dozen (usually male volunteers between the ages of 20 and 40) is the scientific equivalent of putting 100 volunteers on a scale and then weighing them, and concluding that no one in the population can weigh more than 300 pounds because there is no one like that in the group that was weighed.

These types of defense arguments are bad science and based upon faulty logic. They are junk science and junk science based upon speculation or a Defendant biomechanical expert’s generalizations are not sufficient to go to a jury.

If the defendant’s expert backs off even one iota from saying it is impossible for the plaintiff to ever have been injured, then the opinion as to whether the plaintiff was in fact injured is based upon a guess.

Compare the defense biomechanic expert’s extreme position to that of a treating doctor. The treating physician opines that: (1) the plaintiffs medical records are free from reference to prior injury; (2) injuries suffered in the crash are consistent with forces and movements experienced in crashes like this; (3) the physician has treated many other honest and credible people for similar injuries following crashes like this; (4) there is a clear temporal relationship between the crash and the onset of symptoms; and (5) in the physician’s opinion, it is within reasonable medical certainty to conclude that this crash caused the plaintiffs injuries.

Very reasonable testimony.

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