In a prior edition of this Guide, we reported two major developments in federal discovery law: (i) the enactment of federal legislation pertaining to the discovery of electronically stored information ("ediscovery" of "ESI"); and (ii) changes governing the privilege afforded to the work of experts. These remain the most recent major developments in US law related to privilege.

Under federal law, a disclosure of a privileged communication or work product is not a waiver in a state or federal proceeding if "the disclosure is inadvertent" and if the holder of the privilege or protection "took reasonable steps to prevent disclosure" and "promptly took reasonable steps to rectify the error." Parties may, by agreement, ensure that the disclosure does not constitute a waiver of privilege or work product protection. The federal court's entry of an order incorporating such an agreement makes that agreement binding on all parties in future state or federal proceedings. No clear standard has yet emerged for determining what constitutes a party's "reasonable" efforts to prevent the disclosure of privileged information under the rule. Courts have found a waiver of privilege based on the determination that the party who disclosed the privileged communications either failed to take sufficient care in reviewing documents for privilege before the disclosure or failed to provide information sufficient to allow the court to assess the reasonableness of efforts to avoid such disclosure.

The other major development in US privilege law in recent years was the enactment of changes to Rule 26 of the Federal Rules of Civil Procedure ("Rule") to expressly extend work product protection to all drafts of expert reports in any form and to exempt from discovery most communications between the trial counsel for a party and those of its testifying experts whom the Rule requires to submit an expert report. Under this "attorney-expert" privilege, all communications, whether oral, written, or electronic, between trial counsel and the expert are protected unless they relate to the testifying expert's compensation; they identify facts or data that the party's attorney provided and that the expert considered, in forming the opinions expressed; or they identify assumptions that the party's attorney provided to the expert, and upon which the expert relied in forming their opinions. Since the enactment of these changes, courts have grappled with questions left unanswered by the Rule's new language. For instance, district courts have come to different conclusions as to whether an expert's notes (as opposed to their drafts of an expert report) related to a matter are protected. Thus, in In re Application of Republic of Ecuador, expert's notes, task lists, outlines, memoranda, presentations, and draft letters were not protected as draft reports, whereas in SKF Condition Monitoring, Inc. v. Invensys Sys, expert's notes and outlines were exempt from discovery. Similarly, there is some uncertainty as to whether communications between attorneys and experts who are not required by the rule to submit an expert report are privileged or discoverable.