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December 18, 2015 Practice Points

10 Tips for Posturing Your Case for Successful Daubert Challenge

A checklist to help you get it right the first time.

By John D. Sear

Litigators file hundreds of Daubert motions every year. Appellate courts frequently affirm trial court rulings on them. The high rate of affirmance stems from the deference given to trial court Daubert decisions. Trial courts will get it right the first time if you follow this tried-and-true checklist.

1. Scour Scientific Literature
"The courtroom is not the place for scientific guesswork, even of the inspired sort. Law lags science; it does not lead it." Rosen v. Ciba-Geigy Corp., 78 F.3d 316, 319 (7th Cir. 1996). Peer-reviewed literature helps to define the boundary between admissible testimony and unscientific guesswork. Scouring the scientific literature up front is the best way to find that boundary and gain insight into the appropriate methodologies employed by knowledgeable experts in the field.

2. Scour the Expert's Published Literature
Scientific literature published by the expert offers ammunition for a successful Daubert attack. "The ultimate test of a scientific expert's integrity is her readiness to publish and be damned." Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311, 1318 (9th Cir. 1995) (quotations omitted). When experts publish, they must adhere to rigorous standards of scientific integrity that prohibit unfounded conclusions—their litigation opinions should be held to the same standards. Knowing what the expert has and has not written and published will better equip you to challenge the testimony.

3. Apply Governing Law
Work within the framework established by your judge, your district, and your circuit. E.g., United States v. Nacchio, 608 F. Supp. 2d 1237, 1252 n.23 (D. Colo. 2009) ("A very homely, and admittedly imperfect analogy that I routinely use is that an opinion is the witness's end product. It is like a 'cake'" that needs a baker (qualified expert), recipe (methodology), and ingredients (facts and data).). When a judge articulates an approach, ignore it at your peril.

4. Exploit the Manual on Scientific Evidence
The Manual on Scientific Evidence, now in its third edition, contains chapters, or "reference guides," on a variety of topics commonly the subject of expert testimony. Available on the Federal Judicial Center's website,, the manual educates judges on topics within the Daubert context. The judge deciding your motion will refer to the manual—you should too.

5. Exploit the Expert's CV
Experts routinely fill their CVs with memberships in professional organizations. Most organizations have their own standards members should follow. Disregarding those standards without good reason casts doubt upon the scientific integrity of the expert's work. Experts can hardly assert that they have employed scientifically rigorous analysis when they disregard the principles of their own organizations.

6. Question Opinions Expressed with Absolute Certainty
Daubert cautions that nothing in science is known with absolute certainty. When experts proclaim knowledge of something with certainty, but the scientific knowledge does not share that certainty, they expose themselves to the criticism that their testimony is unreliable. What's good for the goose is good for the gander—the need for scientific integrity applies to everyone's experts.

7. Narrowly Focus Daubert Challenges
Why challenge an expert's qualifications when the expert is qualified enough to meet the liberal qualification standard of Rule 702? Instead, use the expert's strengths to your advantage. An expert who is highly credentialed and degreed should know better than to state opinions formed unreliably and unsupported by the available scientific knowledge.

8. Remember Daubert Factors Are Guidelines, Not Rules
The Daubert factors—testing, peer-review and publication, rate of error and existence of standards, and general acceptance—are guidelines for assessing scientific reliability and relevance, not hard and fast requirements that all testimony must satisfy in every case. Resist the temptation to shoehorn all Daubert reliability criteria into your argument when one or more of them may not apply.

9. Consider Applicable State Law
State law plays a role in the Daubert analysis, particularly when the party relies upon the expert's testimony to meet the burden of proof. Daubert challenges must consider state law on burden of proof and sufficiency. If the testimony does not satisfy those burdens, it is not relevant and, in the words of Daubert, probably does not fit.

10. Evaluate Each Step in the Expert's Analysis
Unreliability in any step of the expert's analysis can render the testimony inadmissible. Scrutinizing each step in the expert's analysis will strengthen the argument for exclusion.

Following this checklist will help focus the issues for the trial court, increase the chances of success on any Daubert motion, and preserve the trial court's favorable ruling on appeal.

John D. Sear is with Bowman and Brooke LLP in Minneapolis, Minnesota. Reprinted in shortened form with permission from the February 2010 issue of LJN's Product Liability Law & Strategy, ©2010 ALM Media Properties, LLC. Further duplication without permission is prohibited. All rights reserved.

Copyright © 2015, American Bar Association. All rights reserved. This information or any portion thereof may not be copied or disseminated in any form or by any means or downloaded or stored in an electronic database or retrieval system without the express written consent of the American Bar Association. The views expressed in this article are those of the author(s) and do not necessarily reflect the positions or policies of the American Bar Association, the Section of Litigation, this committee, or the employer(s) of the author(s).