A testifying expert’s qualifications are almost always challenged. At the outset, an attorney should review a potential expert’s qualifications and experience to make sure that the expert has substantive expertise in the relevant subject matter and no prior reports or testimony conflict with the case the expert is currently being considered for. Additionally, it is absolutely critical to review an expert’s history of Daubert challenges and disqualifications. Obviously, if the potential expert has been criticized or disqualified in a similar case or subject matter, the expert likely shouldn’t be retained.
Under Rule 26 of the Federal Rules of Civil Procedure, in addition to the disclosure of the expert witness’s qualifications, publications, testimony, and compensation, the expert report must contain a complete statement of the expert’s opinions, the data of other information considered by the expert in forming such opinions, and any exhibits that will be used to summarize or support the expert’s opinions.
Rules differ across jurisdictions, so attorneys need to know the rules that govern in a particular case. For example, sometimes an expert witness’s draft reports are shielded from discovery, but in some jurisdictions draft reports are not. But even when communications between a party’s attorney and an expert witness are protected, there are three exceptions: communications that(i) relate to the expert’s compensation; (ii) identify facts or data that the attorney provided and that the expert relied on in forming opinions; or (iii) identify assumptions that the attorney provided and that the expert relies on in forming opinions.
A testifying expert can be deposed by another party in the case. Deposition questions usually cover an expert’s qualifications, analysis, methodology, report, and key assumptions, including rejected analyses and unused information. Opposing counsel often use depositions to narrow the scope of an expert’s testimony by confirming what the expert is not going to testify about at trial.
In federal court and most state courts, the trial judge provides a gatekeeper function and will apply the Daubert standard to determine whether an expert’s testimony is based on scientifically valid reasoning and whether it has been properly applied to the facts at issue. The Daubert standard has five factors:
- whether the theory or technique in question can be and has been tested;
- whether it has been subjected to peer review and publication;
- its known or potential error rate;
- the existence and maintenance of standards controlling its operation; and
- whether it has attracted widespread acceptance within a relevant scientific community.
Anything the expert says at the deposition can be used to impeach the expert at trial so the deposition testimony must be consistent with the expert’s anticipated trial testimony.