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Daubert Expert Motions – Best Practices Should be followed to be Successful

The Way eDiscovery Should be Done…..





Challenging an expert witness is not like challenging a general witness. There are complicated rules outlined under Federal Rules of Evidence 702 and 703 that govern this procedure.   The procedure for Daubert motions resulted from the 1993 Supreme Court case, Daubert v. Merrell Dow Pharms., 509 U.S. 579 (U.S. 1993).  Assuming that your motion is accepted and a hearing is scheduled, you are up against expert witnesses who testify for a living.  They are extremely courtroom savvy, have experienced legal interaction and they are usually subject matter experts which makes it difficult to get them off track.  And perhaps even more importantly, judges are far from ecstatic when they see a Daubert motion sitting on their desk, anticipating the expert-bashing and jargon-filled science lessons they know will follow.

Daubert motions to exclude expert testimony should not be filed lightly.  They are complex and time consuming in nature. Attorneys must be extremely confident that it is worth the effort and the potential negative impact on the court.  Daubert motions may require special expertise to be successful and in fact have become a sub specialty area of the law.  There are some Best Practices which should be followed when filing a Daubert Motion, regardless of whether the decision is made to perform the work in-house or hire outside expertise.

What is a Daubert Motion?

A Daubert motion is a specific type of motion in limine.  It is raised before or during trial to exclude the presentation of “unqualified evidence to the jury”.  Daubert motions are used to exclude the testimony of an expert witness who does not possess the requisite level of expertise or used questionable methods to obtain data.

What are the Relevant Factors in Daubert?

Rules 702 and 703 of the Federal Rules of Evidence govern the admission of scientific evidence in federal court. The rules allow expert witnesses greater leniency in their testimony because it is presumed that the expert will have a reliable basis in knowledge and expertise in his field.  The court in Daubert concluded that trial judges should act as a gatekeeper and determine the scientific validity of scientific evidence before admitting it.


The court in Daubert put forth the following guidelines for admitting scientific evidence:

  • Judge is gatekeeper: Under Rule 702, the task of “gatekeeping”, or assuring that scientific expert testimony truly proceeds from “scientific knowledge”, rests on the trial judge.
  • Relevance and reliability: This requires the trial judge to ensure that the expert’s testimony is “relevant to the task at hand” and that it rests “on a reliable foundation”. Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 584-587. Concerns about expert testimony cannot be simply referred to the jury as a question of weight. Furthermore, the admissibility of expert testimony is governed by Rule 104(a), not Rule 104(b); thus, the Judge must find it more likely than not that the expert’s methods are reliable and reliably applied to the facts at hand.
  • Scientific knowledge = scientific method/methodology: A conclusion will qualify as scientific knowledge if the proponent can demonstrate that it is the product of sound “scientific methodology” derived from the scientific method.
  • Factors relevant: The Court defined “scientific methodology” as the process of formulating hypotheses and then conducting experiments to prove or falsify the hypothesis.  Additonally, they must provide a nondispositive, nonexclusive, “flexible” set of “general observations” (i.e. not a “test”) that it considered relevant for establishing the “validity” of scientific testimony:
  1. Empirical testing: whether the theory or technique is falsifiable, refutable, and/or testable.
  2. Whether it has been subjected to peer review and publication.
  3. The known or potential error rate.
  4. The existence and maintenance of standards and controls concerning its operation.
  5. The degree to which the theory and technique is generally accepted by a relevant scientific community.

Rule 702

After the decision in Daubert, Rule 702 was amended to include the additional provisions which state that a witness may only testify if

1)     the testimony is based upon sufficient facts or data

2)     the testimony is the product of reliable principles and methods, and

3)     the witness has applied the principles and methods reliably to the facts of the case.

Additionally, the guidelines in the decision have now been expanded to include technical and specialized knowledge testimony as well.

Executing a Daubert challenge against an opposing party can be the difference between winning and losing a case.  Given the importance of the motion, it is important for any practicing trial attorney to understand:

  • how to execute a Daubert challenge,
  • when to do so, and
  • strategies relating to the execution of such a challenge.

The Expert Institute has published an extremely important article on this topic which is a must read for anyone considering filing a Daubert motion.  It includes the process of launching a successful Daubert challenge against opposing counsel’s expert to help you identify the right situation to deploy a gate keeping challenge, as well as a step-by-step method to give your challenge the greatest chance of success.  CLICK HERE for a link to the article.

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