A recent decision by Justice Fothergill provides welcome guidance for Canadian patent litigators on a recurring issue in complex patent proceedings: the permissible role of counsel in assisting with drafting expert reports. The decision confirms that lawyer involvement, even extensive involvement, in preparing expert reports does not, without more, undermine the independence of an expert or diminish the weight to be given to the expert’s evidence.
dTechs EPM Ltd. v. BC Hydro, 2026 FC 1235
Background
The dispute arose from long-running patent litigation between dTechs EPM Ltd. (dTechs) and British Columbia Hydro and Power Authority (BC Hydro), involving Canadian Patent No. 2,549,087. In the original trial, the Federal Court dismissed dTechs’ infringement claim and held the asserted patent claims invalid for anticipation and obviousness.
On appeal, the Federal Court of Appeal (FCA) largely upheld the trial judgment (2023 FCA 115). However, the appeal took an unusual turn when dTechs obtained new evidence during costs proceedings, including BC Hydro’s expert’s engagement documents and invoices. dTechs argued that these records showed that BC Hydro’s expert had not personally drafted the first versions of his reports and therefore his evidence should have been excluded or given no weight.
The FCA rejected most of dTechs’ arguments but permitted a limited redetermination concerning dependent claim 4, recognizing that the new evidence potentially affected the validity analysis for that claim alone.
The Issue on Remand
The question before Justice Fothergill was narrow:
Did the newly discovered evidence concerning the preparation of dTechs’ expert reports affect the weight that should be accorded to that evidence?
Justice Fothergill emphasized that it was not conducting a fresh admissibility analysis under the Supreme Court’s White Burgess standard. Nor was he reconsidering the entirety of the original validity decision. The sole question was whether the new evidence about how the expert’s reports were prepared diminished the reliability or independence of the expert evidence previously accepted at trial.
The Evidence
The expert’s invoices demonstrated that he had spent substantial time:
- participating in videoconferences with counsel;
- reviewing technical materials;
- commenting on draft reports; and
- revising drafts prepared by counsel.
The invoices did not contain entries indicating that the expert personally drafted the initial versions of his reports. dTechs argued that this absence demonstrated improper lawyer involvement and called into question whether the opinions expressed were truly the expert’s own.
BC Hydro responded with evidence from the expert’s business partner (the expert was now deceased), who described a collaborative process in which counsel posed questions during extensive videoconferences while recording the expert’s answers into a shared working document. The expert then reviewed and commented on successive drafts of his reports.
The Court’s Analysis
Justice Fothergill accepted the business partner’s evidence regarding the report preparation process and found it consistent with both the invoices and the expert’s own description of how his reports had been prepared.
Justice Fothergill relied heavily on the FCA’s earlier observations that:
- patent litigation frequently requires close collaboration between experts and counsel;
- counsel often prepare draft reports based on extensive discussions with experts;
- technical experts are rarely familiar with the legal framework governing claim construction, anticipation, and obviousness; and
- lawyer involvement in drafting does not necessarily detract from the independence of the expert opinion.
Importantly, Justice Fothergill found no evidence that counsel had substituted their own opinions for those of the expert. Rather, the evidence demonstrated that the reports accurately reflected the expert’s substantive views.
Justice Fothergill stated that if the process involved counsel recording answers provided by the expert during videoconferences and converting those answers into draft reports, it would be unsurprising that no docket entries existed for the expert personally “drafting” the reports.
Justice Fothergill ultimately concluded that the reports represented the expert’s independent opinions and that the newly discovered evidence had no effect on the weight of his evidence. Accordingly, the Court reinstated its prior finding that claim 4 of the patent was invalid.
Key Takeaways for Patent Litigators
- Counsel Can Draft Expert Reports
The most significant practical lesson is that the Federal Court continues to recognize the realities of patent litigation. Counsel may take a substantial role in drafting expert reports, particularly where complex legal concepts such as anticipation, obviousness, and claim construction must be addressed. The critical question is whether the report ultimately reflects the expert’s own opinions.
- Process Matters
Although the assistance of counsel is permissible, parties should be able to demonstrate how the report was prepared. The evidence in this case showed a documented process involving meetings, questions, revisions, and expert review. Maintaining records of that process may become important if the expert’s independence is later challenged.
- Expert Review and Adoption Are Essential
Justice Fothergill’s conclusion rested largely on his satisfaction that the expert reviewed the drafts and adopted the opinions expressed in them as his own. Counsel should ensure that experts thoroughly review and approve all substantive portions of their reports before finalizing the reports.
- Independence Challenges Remain Difficult
This decision reinforces that allegations of lawyer influence on experts will generally require evidence that counsel crossed the line from assisting in communication to shaping the substance of the expert’s opinions. Merely demonstrating that counsel prepared initial drafts will rarely be sufficient.
- Cross-Examination Remains the Primary Safeguard
Both the FCA and Justice Fothergill emphasized that concerns about excessive lawyer involvement will normally be explored through cross-examination and reflected in weight rather than admissibility. Parties seeking to challenge expert independence should focus on developing a factual record showing substantive interference with the expert’s opinion.
Conclusion
This decision is an important reaffirmation of a practical reality familiar to every Canadian patent litigator: expert reports are often collaborative products. The Federal Court confirmed that lawyer-drafted reports are not inherently suspect, provided the opinions remain those of the expert and the expert maintains independence. For counsel, the decision underscores the importance of documenting expert interactions, preserving evidence of expert review, and ensuring that counsel’s role remains one of facilitation rather than advocacy masquerading as expert opinion.
dTechs has 30 days to appeal to the Federal Court of Appeal.