Your expert’s opinion must meet the Daubert standard in order to survive a Daubert challenge in federal court or in the states which have adopted Daubert (now a majority of states).  In order for your expert witness to have the best chance to pass the Daubert test, we recommend you suggest to your expert the following:

  1. Only use theories or techniques that have been tested and passed.
  2. Use theories or techniques that are objective.
  3. Specify the known error rate or potential error rate for the method.
  4. Use methods with acceptable error rates.
  5. Produce peer-reviewed literature (i.e., journal studies, reports, and treatises supporting your conclusions and opinions).
  6. Produce reliable scientific data to prove that your methods and conclusions are generally accepted in the scientific community.
  7. Demonstrate that your theories existed prior to the commencement of the litigation
  8. Do not develop novel theories to support conclusions for specific litigation.
  9. Demonstrate that you maintained standards and controls (for example, good laboratory practices and simultaneous blind controls).
  10. Demonstrate that findings can and have been replicated by others.
  11. Demonstrate that your methodology followed the scientific method as it is practiced by at least a recognized minority of scientists in your field.
  12. Offer testimony that is sufficiently tied to the facts of the case to help the jury to resolve a factual dispute.
  13. Avoid relying on the coincidence of temporality.
  14. Avoid extrapolating unjustifiably from an accepted premise to an unfounded conclusion.
  15. Adequately account for obvious alternative explanations.
  16. Demonstrate the same care and accuracy as in regular professional work.
  17. Use the real-world methodology of your field.
  18. Use an appropriate methodology to ensure that your opinion derives from and constitutes a form of specialized knowledge.

James J. Mangraviti, Jr., Esq. is a principal of SEAK, Inc., the expert witness training company. Jim is the co-author of How to Prepare Your Expert Witness for Deposition.  SEAK provides expert witness deposition, trial and Daubert hearing preparation services for attorneys and expert witnesses.  For more information, please visit