Preparing the Expert Report in a Patent Case – A Collaborative Exercise to be Approached with Caution

December 15, 2022
By Adam Bobker

The recent trial decision in Rovi Guides v. Bell, 2022 FC 1388 is an exceptional case that proves the rule that the preparation of expert evidence in a patent case is necessarily a collaborative exercise between technical expert and patent counsel.  At the same time, the expert is ultimately the sole author of his or her report and must be, and be seen to be, objective and impartial. [1]  If an expert report is partisan, it may be exposed as such in cross-examination.  In this latest Rovi decision, it came out on cross-examination that the expert’s report included passages from a different expert’s report, without attribution.  The Court described this as “plagiarism pure and simple” and said it “puts into real doubt the impartiality and independence of the expert”.  The Court did not exclude the expert’s evidence, but it undermined its weight.

The Court in Rovi cited Moore v. Getahun, 2015 ONCA 55 which commented on the role of counsel in preparing expert reports in patent cases at [55] – [59].  There, the Ontario Court of Appeal cited Medimmune Ltd. v. Novartis Pharmaceuticals UK Ltd. [2011] EWHC 1669 (Pat), for the proposition that “in … patent law, expert witnesses “require a high level of instruction by the lawyers” which may necessitate ‘a high degree of consultation’ involving an iterative process through a number of drafts.”

The Court of Appeal repeated the caution from Medimmune, however, that since “this process entails a risk of loss of objectivity on the part of the expert,” it is “crucial that the lawyers involved should keep the expert’s need to remain objective at the forefront of their minds at all times.”  The Advocates Society, which was an intervener in the Moore v. Getahun appeal, had published Principles Governing Communications with Testifying Experts, which the Court of Appeal said, “provides a thorough and thoughtful statement of the professional standards pertaining to the preparation of expert witnesses”.  These Principles are an appendix to the Moore v. Getahun decision.

For patent litigation counsel, the Medimmune decision contains a patent focused discussion of the process of working with an expert to prepare their report.  The discussion includes the following useful points:

  1. Consultation is proper.  Nevertheless, the expert’s report should be, and should be seen to be, the independent product of the expert uninfluenced as to form or content by the exigencies of litigation.[2]
  2. Counsel should ensure that the expert is properly instructed and put in a position to express an independent and impartial opinion on such questions as the identity and attributes of the skilled person, their common general knowledge, and whether something would or would not be obvious.[3]
  3. The expert will often require a high level of instruction from counsel and considerable assistance from counsel in drafting their report.[4]
  4. The drafting of the report involves a steep learning curve for both the expert and counsel.  Counsel is learning the technology and the expert is learning enough of the law to understand the questions he or she must address.  A high degree of collaboration is required.  In many cases, counsel drafts the report based on what the expert has told them and then the expert amends it.  The final report will be the result of an iterative process, and many drafts.[5]
  5. Given the high degree of collaboration that is inevitable, there is a risk of the expert losing their objectivity and impartiality. Counsel needs to keep this at the forefront of their mind.  If an expert comes across as an advocate on cross-examination it can reduce, if not eliminate, the value of their evidence to the client’s case.[6]

Working with an expert to prepare their report is a challenging and interesting aspect of the practise of patent litigation. The recent Rovi decision is a reminder to keep the cross-examiner in mind when preparing the expert report.  The goal is to ensure that after cross-examination at trial, the expert report continues to be seen as having been authored by a person who was there to assist impartially the Court on matters relevant to his or her expertise.


[1] The Code of Conduct for Expert Witnesses (Rule 52.02 of the Federal Courts Rules) provides that the expert has an overriding duty to assist the Court impartially on matters relevant to his or her expertise.  This duty overrides any duty to a party to the proceeding, including person retaining the expert witness.  An expert is to be independent and objective.  An expert is not an advocate for a party.

[2] Medimmune at [104]-[106] and Whitehouse v. Jordan, [1981] 1 WLR 246 and The Ikarian Reefer [1993] 2 Lloyds Rep 68 at 81-82

[3] Medimmune at [107]

[4] Medimmune at [109]-[110]

[5] Medimmune at [110]

[6] Meddiumune at [111]


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