Steven Balson-Cohen. Courtesy photo.

Many litigants rely on expert testimony as an important evidentiary aid in proving or defending their cases. The point of expert testimony is to provide information not within the ordinary scope of a lay jury’s knowledge that will assist them in making an informed decision as to any medical or other scientific evidence particularly as it relates to causation of injuries. As the Court of Appeals noted in Dufel v. Green, 84 N.Y. 2d 795, 622 N.Y.S. 2d 900 (1995), “(a) medical judgment on the seriousness of plaintiff’s injury when the jury may not be able to resolve the question without expert opinion evidence is consistent with…legislative intent.”

The Science of Biomechanical Engineering

Biomechanical Engineering is the application of mechanical engineering principles to the human anatomy and physiology. It is the study of what bones, joints, intervertebral discs, ligaments cartilage etc. are made of and how these components of the human body move and function, what types of forces and stresses these body components are subjected to and what types of forces, stresses and motions would cause these body components to exceed their natural physiological limits. A similar but more succinct judicial definition of biomechanics is found in McDonald v. Colonial Steel, (Sup. Ct. Kings Co. 2006) where Justice Marc Partnow, (quoting a biomechanical expert at trial), stated that biomechanics is “the application of engineering principles to the functioning of the human body.” No less an authority than “The Reference Manual on Scientific Evidence” which is published by the Federal Judicial Center of the National Research Council of The National Academies (3rd Edition – 2011) states as follows on page 942:  “Common personal injury cases may also present issues on which engineering testimony may be helpful. Such disputes often turn on testimony as to how a particular trauma occurred. Our discussion of biomechanical engineering highlights some of the issues. In a car accident case, properly qualified engineers may provide opinion testimony regarding how an accident occurred; including reconstructing the conduct of each of the parties and how that conduct affected the accident.”

Although technical and somewhat complicated, the successful practitioner must possess a well-functioning understanding of the areas of how biomechanical engineers go about their analysis.  Concepts that are part of the biomechanical analysis are noted here briefly and are as follows:

  • Mechanism of Injury (how the accident happened, the forces involved in trauma and, thus, the potential severity for injury);
  • Energy Based Crush Analysis (use of post-collision vehicle crush measurements to calculate the energy dissipated in a collision).
  • Delta V – or change in speed due to impact (used as a measure of the severity of a traffic collision by calculating the change of velocity).
  • Occupant Kinematics (the explanation of the motion of occupants inside a vehicle during a crash using Newton’s Three Laws of Motion to explain the paths that vehicle occupants follow).
  • Specific vehicle information based on VIN number and damages estimates with photos.

Explaining the ‘Frye’ Standard

In New York, the standard for admitting expert and/or scientific based testimony has been set out in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923),  a case discussing the admissibility of polygraph test as evidence. The Court in Frye held that expert testimony must be based on scientific methods that are sufficiently established and accepted in the subject scientific community.  The court explained as follows: “whether the accepted techniques, when properly performed, generate results accepted as reliable within the scientific community generally.” People v. Wesley, 83 N.Y.2d 417 (1994). In Lugo v. New York City Health and Hospitals Corporation, 89 A.D. 3d 42, 929 N.Y.S.2d 264 (2nd Dept. 2011), the Court held that a Frye inquiry “is directed at the basis for the expert’s opinion and does not examine whether the expert’s conclusion is sound.  “Frye is not concerned with the reliability of a certain expert’s conclusions, but instead with ‘whether the experts’ deductions are based on principles that are sufficiently established to have gained general acceptance as reliable.” The Lugo Court added that it is not the court’s job to decide who is right or wrong, “but rather to decide whether or not there is sufficient scientific support for the expert’s theory.”

The ‘Parker v. Mobil Oil’ Analysis

The Court of Appeals in Parker v. Mobile Oil Corporation, 7 N.Y. 3d 434, 824 N.Y.S. 2d 584 (2006) stated as follows: “the Frye test asks whether the accepted techniques, when properly performed, generates results accepted as reliable within the scientific community generally (and) holds that while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs. It emphasizes counting scientists votes, rather than on verifying the soundness of a scientific conclusion.”  

The ‘Parker’ Hearing

Some evidentiary based controversies move beyond the novelty of science analysis related to Frye. In essence, the Frye hearing morphs into an evidentiary inquiry when the party seeking preclusion realizes that a strictly Frye inquiry will not achieve the desired expert preclusion. The party seeking preclusion has in essence a second chance by using the analysis of Parker v. Mobil Oil. The Court in Parker stated: “(the) Frye inquiry is separate and distinct from the admissibility question applied to all evidence-whether there is a proper foundation   - to determine whether accepted methods were appropriately employed in a particular case”…the focus moves from the general reliability concerns of Frye to the specific reliability of the procedures followed to generate the evidence proffered and whether they establish a foundation for the reception of evidence at trial. The Parker Court was mindful of preventing the establishment of impossible standards as a prerequisite to the admission of evidence. The Court stated: “We recognize the danger in allowing unreliable or speculative information…to go before the jury…but it is similarly inappropriate to set an insurmountable standard that would effectively deprive (a party) of their day in court”.

Justice York’s ‘Frye’ Analysis

In Selig v. Pfizer, 185 Misc. 2d 600, 713 N.Y.S.2d 898 (S. Ct. NY Co. 2000), aff’d. 290 A.D. 2d 319, 735 N.Y.S. 2d 549 (1st Dept. 2002), Justice Louis B. York gave the most concise and clear elucidation of New York’s Frye standard as follows: “The Frye rule as applied in New York differs from the … federal standard established by the United States Supreme Court in Daubert v Merrell Dow  (509 U.S. 579, 1993)Under Frye, the court does not determine whether a scientific technique is reliable but, instead, whether there is a consensus in the scientific community as to its reliability. Thus, the Frye test emphasizes “counting scientists votes, rather than verifying the soundness of a scientific conclusion.”

Ask Whether ‘Frye’ Test Is Implicated

When faced with a “Frye” motion, counsel can ask initially whether the Frye test is even implicated if the proposed testimony is not a novel scientific theory. “A court is only required to conduct an inquiry, concerning general acceptance, pursuant to Frye, in situations in which a party seeks to rely upon novel scientific, technical or other concepts involving expertise… here, the opinion of plaintiff’s expert was not based on novel theories and did not warrant a preliminary Frye-type hearing.” See, Krackmalnik v. Maimonides Med. Ctr., 142 A.D.3d 1143, 1144 (2d Dep’t 2016) and People v. Brooks, 2018 WL 1413456 (N.Y.), (Court of Appeals March 2018) 2018 Slip Op. 01956.

Counsel should therefore follow the following general guide in educating the trial court as to the admissibility of expert testimony as follows:

    • Demonstrate that the expert providing the challenged testimony is sufficiently qualified to testify as an expert witness with respect to the pertinent issue; See Matott v. Ward, 48 N.Y.2d 455, 459 (1979) where the Court stated: “a predicate for the admission of expert testimony is that its subject matter involve information or questions beyond the ordinary knowledge and experience of the trier of the facts. The expert should be possessed of the requisite skill, training, education, knowledge or experience from which it can be assumed that the information imparted or the opinion rendered is reliable.” State v. Jason C., 51 Misc. 3d 553, (Supreme Court, N.Y. County 2016).
    • Demonstrate that the proposed testimony is based on scientific principles or procedures that have been sufficiently established to have gained general acceptance in the particular field involved.  See, Parker v. Mobile Oil Corporation, 7 N.Y. 3d 434, 824 N.Y.S. 2d 584 (2006).
    • Demonstrate that the expert’s testimony is relevant to the issues in the case. See, e.g., People v. LeGrand, 8 N.Y.3d at 456-57, 459; Jason C., 51 Misc. 3d at 557. “Evidence is relevant if it has any tendency in reason to prove the existence of any material fact, i.e., if it makes determination of the action more probable or less probable than it would be without the evidence.”
    • Although not technically part of a Frye hearing, in actual practice counsel may also have to demonstrate that the expert has sufficient information based on admissible evidence to arrive at his/her conclusions. This last requirement is not limited to biomechanical experts but is a separate and distinct requirement of all experts who are proffered to testify in a New York State Court.

Challenges to Admission of Evidence

With increasing frequency, counsel who retain a biomechanical expert in an automobile accident case are seeing challenges to the admission of such evidence usually on one of the following grounds:

(1) The use of biomechanical engineering principles to determine that a specific injury cannot occur to a specific individual in a specific accident has not been generally accepted in the scientific community, and as a result cannot meet the Frye admissibility standards;

(2) The biomechanical engineer is not competent to testify as to medical causation of an injury;

(3) The proposed witness lacks a proper factual foundation to reach any conclusions;

Beware Bait and Switch

  • If possible, never hold any motion argument or Frye hearing expect on the record via a court reporter.
  • Beware the bait and switch i.e. many counsel who seek to preclude biomechanical evidence wind up merely challenging the factual foundation of the expert.
  • In addition many such motions have no expert affidavit challenging the credentials, methodology, accepted science or conclusions of the defense expert.
  • Beware citations from other jurisdictions. Occasionally the practitioner may see a brief that proffers out of state case many of which are decided under the Daubert Standard. Given the wealth of authority in New York, it is unnecessary to circumnavigate the United States for such case authority.  
  • Beware citation to lower court case in New York that have ruled on a biomechanical experts. Such case specific opinions as to a particular expert may not be controlling on a appellate department wide basis and that each case is unique in terms of its fact patterns.

Experts Admitted to Reasonable Degree

It is well known and accepted that expert opinions in New York are admitted to a reasonable degree (not absolute degree) of medical and/or scientific certainly. See, Matott v. Ward, 48 N.Y. 2d 455, 423 N.Y.S. 2d 645 (Court of Appeals 1979) and Ratner v. McNeil-PPC Inc., 91 A.D. 3d 63, 933 N.Y.S. 2d 323 (2d Dept. 2011). Any list of the so called deficiencies in the expert’s testimony should be framed by counsel as merely grist for cross examination, not preclusion.


Master and marshal the facts, the law and the science of biomechanics and present them in a logical and clear fashion to the Court who is about to rule on admissibility. If the Court understands each step and how you are fulfilling all legal requirements along the way you will stand in a very good position to argue your points in a Frye hearing and win.

Steven Balson-Cohen is trial counsel at Baker, McEvoy, Morrissey and Moskovits.