Switching Sides: When Do Courts Disqualify Expert Witnesses?

1. Importance of Expert Witnesses in IP Litigation: Expert witnesses play a crucial role in intellectual property litigation by interpreting complex technologies and evaluating damages.
   
   

2. Risks of Switching Sides: Courts may disqualify expert witnesses who switch sides in litigation to prevent the misuse of confidential information and to maintain the integrity of the judicial process.
   
   

3. Legal Standards for Disqualification: Disqualification decisions depend on whether a confidential relationship existed and whether any confidential information was disclosed to the expert during their prior engagement.

In intellectual property litigation, expert testimony often plays a decisive role. Experts interpret complex technologies, evaluate damages, and guide fact-finders through specialized subject matter. But what happens when an expert changes allegiances—offering opinions for one party after previously consulting with or being retained by the opposing side?

Courts recognize the risks posed when an expert “switches sides.” Principal among those risks being the potential misuse of confidential information obtained through a prior relationship. While disqualification is considered a “drastic measure,” it is sometimes necessary to protect the integrity of the judicial process.

This article explores when and why an expert may be disqualified after switching sides, the legal standards courts apply, and how parties can avoid common pitfalls through two case studies.

Asus Technology Licensing Inc. v. AT&T Corp.

In Asus Technology Licensing Inc., the Eastern District of Texas disqualified two experts from further participation in a patent infringement case.[1] In that case, both experts had been engaged by the plaintiffs to perform pre-suit analysis on the infringement of plaintiffs’ patents.[2] In the course of their work, the experts reviewed confidential material provided by the plaintiffs, including claim charts.[3] Seven weeks before the plaintiffs filed their case, the two experts terminated their engagement agreement.[4]Several months after the filing of the complaint, the two experts were engaged by the defendants.[5]The court framed the disqualification issue as a two-prong test.

In determining whether an expert should be disqualified, the Court asks two questions:

First, was it objectively reasonable for the first party who claims to have retained the expert to conclude that a confidential relationship existed?

Second, was any confidential or privileged information disclosed by the first party to the expert?

Koch Ref. Co. v. Jennifer L. Boudreau M/V, 85 F.3d 1178, 1181 (5th Cir. 1996). “Only if the answers to both questions are affirmative should the witness be disqualified.” Id.[6]

First, the court found that because “Plaintiffs retained the expert for pre-litigation/licensing investigation,” which is “well understood to involve confidentiality as it often relates to litigation strategy,” it was objectively reasonable for the plaintiffs to conclude that a confidential relationship existed with the experts.[7] Second, the court found that because “Plaintiffs provided infringement charts... generally prepared in anticipation of litigation by or at the direction of attorneys,” it was “clear the experts received confidential or privileged information.”[8]

While, during their engagement by the plaintiffs, the two experts had provided notice that “they would not be adverse to Ericsson,” the court found that the plaintiffs reasonably understood this to mean that the experts would not work for plaintiffs against Ericsson. [9] Such was insufficient to provide notice that experts would work for Ericsson against the Plaintiffs.[10]Further, the court found that the experts’ avoidance of analyzing base station claims for plaintiffs (in order to not be adverse to Ericsson) did not mitigate the harm to the plaintiffs of the experts switching sides to opine for the defendants.[11] The subject matter on which the experts intended to opine for the defendants and that on which they had already opined for the plaintiffs were “closely related.”[12]

Vineyard Investigations v. E. & J. Gallo Winery

In Vineyard Investigations, the Eastern District of California declined to disqualify a plaintiff’s expert who had formerly been employed by the defendant.[13] The plaintiff, Vineyard Investigations, engaged Dr. Mark Greenspan, an independent consultant to wineries and winegrape growers, as an expert witness.[14]Dr. Greenspan had previously worked for the defendant, E. & J. Gallo Winery, for a period of nine years, ending nineteen years before the filing of the case.[15] The defendant sought to exclude Dr. Greenspan from the case based on his former employment by the defendant during which he allegedly had access to nonpublic information relevant to the case.[16]

“A trial court has the inherent power to disqualify expert witnesses,” the court explained, “consistent with its broad discretion ‘to protect the integrity of the adversary process, protect privileges that otherwise may be breached, and promote public confidence in the legal system.’”[17] “However, ‘disqualification is a drastic measure that courts should use reluctantly and rarely.’”[18]

With respect to the legal framework for analyzing expert disqualification, the court observed that “there is no brightline rule,”[19] but “courts commonly require the party seeking disqualification to bear the burden of showing that ‘(1) the adversary had a confidential relationship with the expert and (2) the adversary disclosed confidential information to the expert that is relevant to the current litigation.’”[20] “‘Generally, both factors must be present for disqualification to be appropriate,’” the court stated.[21]Courts also take into account “whether disqualification would be fair to the affected party and would promote the integrity of the legal process.”[22]

With respect to the first factor, whether the adversary had a confidential relationship with the expert, the court explained that “the focus of the inquiry is on ‘whether there was a relationship that would permit the litigant reasonably to expect that any communications would be maintained in confidence.’”[23] While the defendant in Vineyard Investigations failed to produce any confidentiality agreement between itself and Dr. Greenspan, the court nevertheless “assume[d] without deciding that Dr. Greenspan’s prior employment... constituted a prior confidential relationship sufficient to establish the first factor.”[24] It was able to do so because it found its analysis of the second factor to be dispositive.[25]

With respect to the second factor, whether the adversary disclosed confidential information to the expert that is relevant to the current litigation, the court defined “confidential information” as “that which is ‘of either particular significance or [that] which can be readily identified as either attorney work product or within the scope of the attorney-client privilege.’”[26] The court observed that there is “an existing split in the case law as to whether prior disclosures of purely technical information constitute ‘confidential information’ for the purposes of the second factor,”[27] but that “the majority view,” which the court adopted, was “that prior disclosure, not made in preparation for the then-pending litigation, of confidential technical information to a proposed expert witness does not justify disqualifying the expert, at least not when the confidential technical information is otherwise discoverable.”[28]Because the defendant did not establish that it had disclosed “any relevant confidential nondiscoverable information [to Dr. Greenspan] during the course of his former employment,” the court found that the defendant had not established the second factor.[29] “Therefore,” the court concluded, the case was not “one of those ‘rare’ instances in which it is appropriate for the Court to exercise its discretion to disqualify Dr. Greenspan.”[30]

Conclusion

Switching sides may not always disqualify an expert—but when it threatens to expose confidential information or undermine trust in the legal process, courts may intervene. By understanding the legal standards and proactively managing expert relationships, litigants can ensure their experts are not disqualified and experts in past cases are not used unfairly to harm their clients’ interests.

Endnotes

1. Asus Tech. Licensing Inc. v. AT&T Corp., No. 2:23-CV-00486-JRG-RSP, 2024 WL 4026671, at *1 (E.D. Tex. Sept. 3, 2024).
2. Id. 
3. Id. 
4. Id. 
5. Id. 
6. Id. 
7. Id. 
8. Id. 
9. Id. 
10. Id. 
11. Id. 
12. Id. 
13. Vineyard Investigations v. E. & J. Gallo Winery, No. 1:19-CV-01482-JLT-SKO, 2024 WL 4931961, at *1 (E.D. Cal. Dec. 2, 2024).
14. Id. 
15. Id. 
16. Id. The defendant also sought to disqualify Dr. Greenspan based on his consulting relationship with the defendant’s competitors. Id.
17. Id. at *2 (quoting or citing Ziptronix, Inc. v. Omnivision Techs., Inc., No. C-10-05525 SBA EDL, 2013 WL 146413, at *1 (N.D. Cal. Jan. 14, 2013); Koch Ref. Co. v. Jennifer L. Boudreaux MV, 85 F.3d 1178, 1181 (9th Cir. 1996); Campbell Indus. v. M/V Gemini, 619 F.2d 24, 27 (9th Cir. 1980)).
18. Id. (quoting United States v. Kernen Constr., No. 217CV01424WBSDMC, 2018 WL 5023411, at *1 (E.D. Cal. Oct. 16, 2018)).
19. Id. (citing Hewlett-Packard Co. v. EMC Corp., 330 F. Supp. 2d 1087, 1092 (N.D. Cal. 2004)).
20. Id. (citing Jones v. Toft, No. 2:11-CV-0192 MCE EFB, 2013 WL 2102972, at *2 (E.D. Cal. May 14, 2013), report and recommendation adopted, No. 2:11-CV-0192 MCE EFB, 2013 WL 4010315 (E.D. Cal. Aug. 5, 2013); Est. of Michael Wilson by & through Jackson v. Cnty. of San Diego, No. 320CV00457RBMDEB, 2023 WL 8313230, at *2 (S.D. Cal. Dec. 1, 2023); Chan v. ArcSoft, Inc., No. 19-CV-05836-JSW, 2023 WL 5068495, at *4 (N.D. Cal. Aug. 8, 2023)).
21. Id. (quoting Chan, 2023 WL 5068495, at *4).
22. Id. (quoting Chan, 2023 WL 5068495, at *4).
23. Id. (quoting Hewlett-Packard Co., 330 F. Supp. 2d at 1093).
24. Id. at *3.
25. Id. 
26. Id. at *2 (quoting Hewlett-Packard, 330 F. Supp. 2d at 1094)
27. Id. at *3 (citing Tabaian v. Intel Corp., No. 3:18-CV-00326-HZ, 2018 WL 4566257, at *5 (D. Or. Sept. 22, 2018); 

    Oracle Corp., 2012 WL 2244305, at *7; Pellerin v. Honeywell Int’l Inc., No. 11CV1278-BEN CAB, 2012 WL 112539, at *2 (S.D. Cal. Jan. 12, 2012), Space Sys./Loral v. Martin Marietta Corp., No. CIV. 95-20122 SW, 1995 WL 686369, at *2 (N.D. Cal. Nov. 15, 1995).

28. Id. (quoting Edwards Vacuum LLC v. Hoffman Instrumentation Supply, Inc., No. 3:20-CV-1681-AC, 2020 WL 7360682, at *7 (D. Or. Dec. 15, 2020)).
29. Id. at *4. 
30. Id.