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Daubert Motions: Challenging an Opponent’s Expert

Christine Funk

Written by
— Updated on February 2, 2023

Daubert Motions: Challenging an Opponent’s Expert

If you have a case involving expert witnesses or the potential for expert testimony, it is never too soon to consider challenging the opponent’s expert under Daubert.  There are both legal and strategic advantages to Daubert challenges.

The Daubert Standard Generally

As a preliminary matter, a brief explanation of the Daubert standard is in order.  In 1993, the United States Supreme Court held the Federal Rules of Evidence superseded the Frye Standard for admitting expert scientific testimony in federal trials.  Under Federal Rule of Evidence 702, which governs the testimony of expert witnesses offering opinions, witnesses qualified by “knowledge, skill, experience, training, or education” may testify in the form of opinion or otherwise if the following four factors are met:

  1. The knowledge will assist the trier of fact ether understand the evidence or make a fact determination at issue;
  2. The expert’s testimony is “based on sufficient facts or data”;
  3. Reliable principles and methods were used in coming up with the opinion; and
  4. The principles and methods were applied in a manner that is reliable in the case at hand.

Fed.R.Ev. 703. 

Daubert provides when courts are making a preliminary assessment of the testimony pursuant to Rule 702, courts may consider a number of factors, including:

  1. Whether the theory has been and can be tested;
  2. Whether the method has been through the rigors of peer review and publication;
  3. The error rate, if known, or the potential error rate;
  4. Standards that exist for the method, as well as the maintenance of the standards during the testing at issue; and
  5. Whether there is widespread acceptance in the scientific community.

Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

The Timing of a Daubert Challenge

Any litigation strategy involving experts includes considering the timing of a Daubert challenge. Some courts prefer to handle Daubert challenges via a motion in limine.  Others consider a Daubert challenge on its own.  If the ruling is dispositive for one side, it may be appropriate to launch the Daubert challenge early, in connection with a motion to dismiss. Another consideration is, of course, the judge’s background.  Unless the judge has a scientific mind, they may want plenty of time to consider the testimony and briefs before making a ruling.  While some attorneys choose to hold a Daubert hearing in the middle of trial, this approach has few advantages. It is less likely to result in settlement. Additionally, the court may issue a decision having given the issue less thought and consideration than if the court has several weeks or months to make the decision.

The Extent of a Daubert Challenge

Attorneys should give some thought to the possibility of a Daubert challenge in every case.  The extent of a given challenge will, of course, be based on the facts and circumstances of a particular case.  Consider a few hypotheticals to illustrate the variety of potential challenges.

The Paper Challenge Hypothetical

An opposing expert provides a curriculum vitae (CV) clearly documenting their education, training, and experience in forensic DNA typing.  During a deposition, the expert reviews some photos from the scene of the accident.  She states, “Based on this photo, I believe the victim’s heart was beating for a few seconds post decapitation.”

In this hypothetical, a written motion in limine may be sufficient for information for a ruling from the judge.  The motion may detail the witness’s training and experience, or lack thereof.  It may explain how her comment about whether the heart stopped beating post, versus pre-decapitation is beyond the scope of her experience.  You may further choose, in support of your motion, to point out the difficulties inherent in studying this type of phenomenon, the dearth of peer reviewed material on the subject, the absence of an error rate.   The standards and procedures for evaluating heart beat, post decapitation, surely extends beyond merely glancing at a photo.  Finally, there is the question of general acceptance in the scientific community.

Getting a court to limit testimony ahead of time, keeping the expert well within the bounds of their expertise, can be the result of a successful Daubert challenge.

 A Challenge with Testimony Hypothetical

Imagine the other side calls an arson expert.  Their report includes technical sounding terms such as “depth of char” and “spauling” and “crazed glass,” all of which support their conclusion the fire was deliberately set.

In this hypothetical, wherein your challenge is to debunk the fire myths that plagued at least a generation of fire fighters, you will likely want testimony, a witness of your own, several learned treatises, and NFPA 921: Guide for Fire and Explosion Investigations to assist you in your challenge.

Where you plan on presenting a significant amount of data, requesting a briefing schedule, along with the possibility for rebuttal briefs, is a good idea.

Types of Challenges

Within the confines of Daubert, there are several different areas one can challenge.  Consider each of these potential areas of challenge in turn:

  1. An expert’s qualifications;
  2. An expert’s methods;
  3. The science relied upon.

An Expert’s Qualifications

In every single case, lawyers should vet the expert.  This includes reviewing their curriculum vitae and confirming its contents.  Degrees should be verified.  Vetting demands confirming both that degrees were received and received in the field claimed.  All publications should be reviewed.  It may not matter to you the order in which the expert is listed as an author, but rest assured, it matters a great deal in the scientific community.  Publications should be read with an eye towards views inconsistent with those expressed in the expert report.

Once the expert’s claimed qualifications have been confirmed, take the time to consult with others in the field, or learned treatises or other documents, to discover the minimum qualifications for an expert in the field.

An Expert’s Methods

Any scientific testing should be done in accordance with written protocols.  Good science dictates validation studies, establishing the method works as expected, provide the basis for these protocols.  It is a good idea to hire your own qualified expert to determine whether 1. Sound scientific principles support the protocols; 2. The analyst followed the protocols; 3. The expert based their conclusions on objective data.

Often times, scientists have more than one method available to them.  When they choose one method over the other, one must question whether the other method would have yielded a different result.  Scientists learn early, “If it’s not written down, it didn’t happen.”  Consequently, scientists document each step they take.  This provides your expert with a real-time play by play, which they use in evaluating the opposing expert’s approach, testing, and conclusion.  Any one of these areas – or all of them, are potential sources of a Daubert challenge.

A Challenge to the Science

In some fields, such as arson and some areas of medicine, scientific discoveries led to debunking much, if not all of a particular field of science.  In other fields, assumptions continue, despite the fact there is no evidence to support the conclusions.  Comparative bullet lead analysis, while perhaps the most famous, is not the only scientific approach relied upon for years, before faulty scientific assumptions came to light.

Just because something has been around for a long time is not a legitimate basis for ignoring the potential for a Daubert challenge.  In particular, an absence of peer reviewed studies in the available literature should sound the alarm bells.

Benefits of a Daubert Challenge

When You Win a Daubert Challenge

When you win a Daubert challenge, the benefits may include dismissal of the case, or weakening of the case for the other side.  This, of course, may result in a more favorable resolution for your client.

When You Lose a Daubert Challenge

There are benefits to your client and your case, even if you lose a Daubert challenge.  Many judges are loathe to keep out expert testimony.  Consequently, your judge may rule your challenge goes to weight, not admissibility.  A Daubert challenge, however, provides you a practice run at presenting and challenging the evidence.  Particularly when communicating complex scientific principles, understanding what judges (and, by extension, jurors) will and will not understand can be invaluable.

A challenge also sends the other side a message you are willing to work this case to the fullest extent.  It provides you with a roadmap for future cross examination, as well as areas to avoid in front of the jury.  You will learn both the strengths and the weaknesses of both their case and perhaps your own.  Finally, a Daubert challenge gives you a unique opportunity to evaluate the witness and their ability to testify.  This may inform a subsequent decision to either make an offer or consider an offer from the other side.

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