Expert Evidence in Patent Cases

Expert evidence is crucial to patent litigation and the timely preparation and exchange of written expert reports prior to trial is one of most important steps of preparing for trial. Expert evidence is typically introduced on patent claim construction, validity, infringement and on remedies. Having expert evidence found inadmissible can significantly change the stakes at trial.

The Federal Courts Rules include deadlines for the delivery of expert reports, but typically a detailed schedule for the exchange of reports is set by the case management judge in consultation with the parties. The more detailed the schedule for expert reports, the less likely disputes will arise. Due to the timing, when disputes do arise, it is frequently only days or weeks prior to trial, when the parties are focused on preparing for trial and there is little or no time to fix things, such as by amending or preparing additional reports.

As set out in Rule 258, the Federal Courts Rules require that affidavits, statements or reports of expert witnesses accompany the pre-trial conference memorandum. An expert report is required to be delivered in order for the expert’s evidence to be admissible at trial – see Rule 279. The Rules contemplate that objections to expert witnesses and any other issues arising from the expert reports and qualifications be addressed “as early as possible” (Rule 52.5) and at the pre-trial conference (Rule 262(2)). A schedule for delivery of any responding reports may be issued following the pre-trial conference.

Supplementing the Federal Courts Rules are the Federal Court’s , which generally apply or guide intellectual property proceedings. These guidelines contemplate that any objections to expert reports or expert qualifications be made within 30 days of service of the reports, and no later than 30 days prior to trial.

Through the case management process, more detailed schedules may be developed for the exchange of reports, responding reports and the raising of objections. Often these schedules identify the subject matter of the reports being delivered on particular dates such as which reports will address claim construction, validity and infringement. Reply reports that address new issues included in responding reports are not permitted by default but may leave.

When there are disputes about the contents of expert reports, these issues may be considered by the case management judge or by the trial judge. The Guidelines say that any objections raised prior to trial should be made to the case management judge and the trial judge has the sole discretion to agree to hear any such objections at trial, if raised by the parties before the 30-day pre-trial period.

Reply reports, that purport to respond to new issues arising from the other side’s responding reports, seem to be the most common point of dispute as parties disagree about whether the reply report is case-splitting, merely confirmatory or repetitious of the evidence in chief, should have been included in the report in chief, or is something that may be addressed in cross-examination. On the other hand, reply evidence may address new or unexpected positions in responding reports. In some cases, reply evidence, particularly from financial experts may helpfully summarize evidence or identify the points of disagreement between the experts.

A couple of recently reported court decisions highlight some of these disputes. In Paid Search Engine Tools, LLC v. Google Canada Corporation, 2021 FC 587, the defendant sought leave to introduce reply reports on the basis that the plaintiffs responding reports had introduced new positions on the skilled person, patent claim dates, non-infringing alternatives. The rely evidence was not admitted.

In contrast, in Akebia Therapeutics, Inc. v. Fibrogen, Inc., 2021 FC 171, various reply reports were admitted including on the basis that it helpful explained the difference of opinions between the experts or expanded on a fundamental scientific issue in the case, or address issues that could not have been anticipated. In this decision, Justice Barnes summarized his views on the admissibility of reply reports:

Ultimately the resolution of this type of motion will substantially turn on the judge’s view of what best serves the interests of justice and whether the evidence assists the Court in making its decision on the merits, subject, of course, to the avoidance of undue prejudice to a defendant.

As noted above, these disputes about reply reports typically arise on the eve of trial. While parties may work out a resolution, perhaps by separating objectionable from acceptable portions of the reports, if it needs to be resolved by the Court, the dispute can be one of the first instances that the trial judge gets involved in resolving issues between the parties.

Advanced planning, early scheduling of reports with the case management judge and discussions with opposing counsel can reduce unexpected disputes about expert reports. The inadmissibility of key expert evidence can significantly change the balance in a patent trial.