New Jersey Lawyer

THURSDAY JUNE 19, 2008

Admissibility of Biomechanical Testimony

By Gerald H. Baker, Esq.

A recent Supreme Court  provides valuable insight into when the testimony of a biomechanical engineer may be admissible in a low-impact automobile accident case.

New Jersey Rule of Evidence 702 provides that an expert witness may testify in the form of an opinion if scientific or technical knowledge will assist the trier of fact "to understand the evidence or to determine a fact in issue." There are three prerequisites to the admissibility of expert testimony:

(1) the subject matter is beyond the knowledge of the average juror;

(2) the testimony is sufficiently reliable based upon the state of art of the subject matter; and

(3) the expert is qualified by knowledge, skill, experience, training or education.

The second prerequisite -scientific reliability - can be established by proof that the foundation for the expert's testimony is generally accepted in the scientific community, by scientific literature or by judicial decisions.

The party offering an expert witness has the burden to prove the testimony will satisfy the Rules of Evidence. If another party objects, the trial court may conduct a hearing under Rule 104 to determine if the testimony is admissible.

In Hisenaj v. Kuehner, 194 N.J. 6, the New Jersey Supreme Court considered whether the testimony of a biomechanical engineer produced by the defendant was admissible to prove the force of a low-impact collision was not sufficient to cause the plaintiff's injuries.

The vehicle of the plaintiff, Hajrie Hisenaj, was struck in the rear while stopped at an intersection. The defendant produced an accident reconstructionist who concluded the defendant was traveling at less than 8 mph at impact and that the change in velocity of the plaintiff's vehicle, known as the Delta-V force, was less than 5 mph. Thus, the impact felt by the plaintiff would have been no more than a rider on a bumper car at an amusement park.

After the accident, the plaintiff experienced chronic pain in her neck and back. An MRI revealed degenerative disc disease along with a herniated and bulging disc. After four years of treatment, she resorted to surgery to alleviate her pain. She produced the testimony of several experts who concluded the herniated discs were caused by the accident and were permanent.

In response, the defendant offered the testimony of a biomechanical engineer. He explained that biomechanics applies mechanics (the study of forces and motion) to biology (the study of living beings) to explain the physiological effects trauma will have on the function of the human body. He concluded the low-impact collision described by the accident reconstructionist - the minimal velocity of the defendant's vehicle coupled with the minor change in velocity of the plaintiff's car - made it "highly improbable" the accident caused the herniated discs or any chronic injury.

The expert based his opinion upon 17 "scholarly" studies measuring the effects of low-impact collisions on human beings of various ages and genders. The studies were performed over 34 years on more than 200 subjects exposed to simulated rear-end collisions involving Delta-V speeds between 2.5 and 8.0 mph. The studies were peer reviewed and were published in several journals and books on biomechanics.

Exclusion sought

The plaintiff filed a motion in limine to exclude the testimony of the biomechanical engineer because there was no reliable scientific foundation for his opinion. At the Rule 104 hearing, the plaintiff did not present a broad challenge to the general admissibility of the testimony of a biomechanical engineer and did not produce evidence to show the studies were unsound or were not accepted by the scientific community. The plaintiff's only argument was the studies were unreliable because they did not include a sufficient number of subjects with the same age and physical characteristics as the plaintiff.

After the hearing, the trial court admitted the testimony. The jury found the plaintiff had sustained a significant limitation of use of a body function (a non-permanent injury that satisfied type 8 of the 1998 verbal threshold) but did not sustain a permanent injury (type 6 or 7). The jury awarded the plaintiff $50,000 for her non-permanent injury.

The plaintiff appealed. The Appellate Division reviewed the 17 scientific studies even though they had not been introduced into evidence and concluded the testimony did not rest on a reliable scientific foundation. The court found that biomechanical engineers could testify to "the effects that usually flow" from low-impact collisions but not about "the likely effects that would flow to a particular individual." Thus, the Appellate Division reversed the verdict and remanded for a new trial.

The Supreme Court granted certification and reversed. At the outset, the court severely criticized the Appellate Division for "overstepping its bounds" in creating a new record by reviewing documents not admitted into evidence and by substituting its own judgment for that of the trial court. The high court noted it is the function of the parties to "gather and analyze" the evidence and that an appellate court is limited to examining the decision of the trial court for "abuse of discretion."

More important, the Supreme Court found the trial court did not abuse its discretion because the testimony of the expert's witness was based on "actual studies that had examined the outcomes of low-impact accidents on individuals of both genders and of various ages and body types." In addition, the plaintiff failed to discredit those studies during the Rule 104 hearing and did not provide any proof that the studies lacked "scientific reliability."

Reliable studies

The most important lesson from Hisenaj is that testimony of a biomechanical engineer may be admissible in a low-impact auto accident case if the expert relies on studies that are scientifically reliable. In this case, the Supreme Court found the studies were based on 34 years of experimentation with more than 200 people of different genders, ages and body types. The studies were published in the field and accepted by the scientific community.

Nonetheless, the Supreme Court did not conclude the testimony of a biomechanical engineer is always admissible as a matter of law. For one thing, the decision in Hisenaj is fact-sensitive to low-impact accidents. Here, the plaintiff was stopped at the moment of impact and the defendant produced an accident reconstructionist who testified the force of the collision was no greater than two bumper cars at an amusement park - a powerful image.

Obviously, the opinion in Hisenaj would not apply to any case in which the force of the impact (the Delta-V) exceeded 5-8 mph or where the defendant did not produce an accident reconstructionist to establish a foundation for the opinion of the biomechanical engineer.

Likewise, the decision in Hisenaj is based on the record created before the trial court and the inadequacy of plaintiff's attack on the admissibility of the testimony. The opinion does not bar a challenge to admissibility in another case - either as to the expert's qualifications or to the scientific reliability of the expert's studies.

For example, in Suarez v. Espeland, 353 N.J. Super. 191, the Appellate Division held the testimony of a biomechanical engineer was not admissible because the expert did not have comprehensive training in anatomy, physiology or pathology and did not conduct any tests of low-impact collisions on humans. In addition, the studies relied on by the expert were based on tests performed on cadavers or military personnel, not a 41-year-old female civilian.

Potential flaws

More important, the Supreme Court noted the plaintiff's attack on the admissibility of the expert's testimony "fizzled" and that the Appellate Division highlighted several "potential flaws" which "if developed in a trial record, might convince a trial court to exclude expert testimony from a biomechanical engineer concerning the likely injuries that a particular plaintiff would suffer as a result of a low-impact, vehicle-on-vehicle collision."

For example, the Appellate Division commented the studies established that women are at greater risk than men to suffer from flexion-extension injuries (perhaps due to anatomical differences); fewer women were tested than men; more women dropped out due to higher levels of discomfort; a person with degenerative disc disease has an increased susceptibility to spinal injury; and most of the volunteers were younger and healthier than the plaintiff.

Thus, a plaintiff can still attack the admissibility of the testimony of a biomechanical engineer on the grounds the foundation for that testimony (literature and studies) is not "scientifically reliable" and is not "generally accepted by the scientific community." The plaintiff can mount this attack in three different ways:

(1) produce another expert witness; (2) produce other literature and studies; or

(3) cross-examine the defendant's expert.

In Hisenaj, the Supreme Court refused to do that for the plaintiff and refused to allow the Appellate Division to "rehabilitate the record against admissibility."

Gerald H. Baker is a partner in Baker, Pedersen & Robbins in Hoboken and is "of counsel" with Cohen, Placitella & Roth in Red Bank. He focuses on automobile and insurance law. He is a member of the Board of Governors of the Association of Trial Lawyers of America-NJ. His website is http://www.bakeronauto.com/.