Part 4 of our series on How to Be an Effective Expert Witness in Court.

Rule 26 of the Federal Rules of Civil Procedure was amended in 2010, and as of December 1, 2010, the changes to the rule have significantly altered the type and scope of information that can be obtained from an expert witness in the course of discovery. A number of provisions have been put into effect that limit the amount of information an expert witness must now disclose. Prior to the amendments, case law had interpreted the rules to pretty much require the expert to disclose all of his or her communications with the hiring attorney and all drafts of the expert's report. The expert's file was basically an open book, and the only way to avoid making something discoverable was to be certain no written record of the communication was created in the expert's file.

The old Rule 26 required that the expert's report include "the data or other information considered by the witness in forming [the opinions the witness will express.]" The Committee Notes accompanying the rule stated:

The report is to disclose the data and other information considered by the expert and any exhibits or charts that summarize or support the expert's opinions. Given the obligation of disclosure, litigants should no longer be able to argue that materials furnished to their experts to be used in forming their opinions—whether or not ultimately relied upon by the expert—are privileged or otherwise protected from disclosure when such persons are testifying or being deposed.

The concern about what had to be disclosed led in some cases to attorneys hiring two sets of experts, a "consulting" expert and a "testifying" expert. Under the applicable rules, the identity of a consulting expert did not need to be disclosed unless the expert was subsequently designated as a testifying witness. Therefore, an attorney would hire a consultant, give him or her all the information available without fear of disclosure, share the attorney's thoughts and impressions about the case, and then determine whether the expert could give favorable opinions. If so, a comparable second expert would be retained as a testifying expert. The amount of information provided to the second expert was limited to only that which was absolutely necessary for the expert to offer opinion testimony. That expert was then designated as a testifying expert. This was an expensive way to avoid the need for full disclosure under the old version of Rule 26 and it didn't occur in all cases. However, whenever an attorney wanted to freely disclose case information and his thoughts and impressions about the case with the expert this dual track method was the only sure fire way of maintaining confidentiality

The current version of Rule 26 has limitations which are intended to protect the attorney's work product or mental theories or impressions. This enables a free flow of communication between the attorney and the expert. Rule 26(a)(2)(B)(ii) was amended to limit the disclosure obligation to the "facts or data" considered by the expert. According to the Committee Notes, this change was specifically meant to restrict discovery of the attorney's mental impressions or litigation theories shared with the testifying expert. The amended rule now limits disclosures only to "material of a factual nature." In addition, Rules 26(b)(4)(B) and (C) were added to provide protection for drafts of expert reports and communications between the hiring attorney and the expert.