In the recent decision of Zacon Limited v Provincial Doors Inc et al, 2025 ONSC 2954 (the "Court's Decision"), the Ontario Superior Court of Justice (the "ONSC") found that, under the Patent Act, RSC 1985, c P-4 (the "Act"), a re-examination board's decision on the patentability of a patent "does not usurp" the court's ability to determine the validity of the same patent.
Background
In October 2006, Zacon Limited ("Zacon") was issued Canadian Patent No. 2,348,348 entitled "Balanced Ventilation Doors" (the "'348 Patent"). In 2019, Zacon initiated a patent infringement action in the ONSC (the "Action") against, among others, Provincial Doors Inc. ("Provincial") and Pretium Resources Inc. ("Pretium"). In response, Provincial and Pretium both asserted affirmative defences that the '348 Patent was invalid on the grounds of anticipation and obviousness (the "Affirmative Defences").
In May 2021, and pursuant to Section 48.1 of the Act, Provincial requested the Commissioner of Patents to re-examine the '348 Patent on the basis that certain documents anticipated the '348 Patent and/or rendered the '348 Patent obvious (the "Request"). At the direction of the Commissioner of Patents, a re-examination board (the "Board") was established to address the Request. The Board determined that no new question of patentability not previously considered during the prosecution of the '348 Patent had been raised in the Request; therefore, no re-examination of the '348 Patent would occur (the "Board's Decision").
In view of the Board's Decision, Zacon brought a motion under Rule 25.11 of the Rules of Civil Procedure1 in Ontario, asserting that: (i) the Affirmative Defences were identical to the allegations made in the Request to the Commissioner of Patents; and (ii) because the Board's Decision was final and not subject to appeal, allowing the Affirmative Defences to be pleaded in court (and in the Action) would be duplicative of the Request and thus an abuse of the court process.2 Zacon further reasoned that such duplication may result in inconsistent results and would be tantamount to a de facto review of the Board's Decision, despite the finality of the Board's Decision.3
In response, Provincial and Pretium submitted, among other things, that:
- the Request did not deal with the validity of the '348 Patent, but instead dealt with the patentability of the '348 Patent; and
- the requirements for issue estoppel or res judicata had not been met because the defendants in the Action were not all parties to the Request.
Patent Re-Examination and Challenging the Validity of a Patent
Section 48.1 of the Act provides that any person may request a re-examination of any claim of a patent by filing with the Commissioner of Patents prior art, consisting of patents, applications for patents open to public inspection and printed publications, and by paying a prescribed fee. Upon receipt of such a request, the Commissioner of Patents must establish a re-examination board whose mandate is to determine whether a substantial new question of patentability affecting any claim of the patent is raised in the request. If the request raises a substantial new question affecting patentability, the re-examination board would re-examine the claims of the patent. If the request does not raise a substantial new question affecting patentability, the re-examination board would notify the person who filed the request4 and decline to re-examine the claims of the patent.
Generally, there are two ways to challenge the validity of a patent. Under Section 59 of the Act, a defendant in an action for infringement may plead, as a defence, any fact or default which may render the patent invalid; in such a case, the court's finding as to validity would only be binding on the parties to the proceeding. Under Section 60 of the Act, any interested person may bring an action in the Federal Court against the patentee for a declaration that the patent is invalid; in such a case, the court's finding as to validity would be binding at large.
Analysis
The ONSC held that the question put before it in this motion was different than the one that was put before the Board. In particular, the ONSC framed the questions before it and the Board as follows:
| The Board | The Court |
| In light of new information, should the issuance of the '348 Patent be re-examined to determine whether it ought to have issued in the first place?5 | Do the pleadings raise a question as to whether the prior art defects alleged by the defendants, along with others considered by the Examiner, render the '348 Patent invalid?6 |
Regarding the question before the Board, the ONSC noted that the Board was tasked with determining "whether documents submitted by Provincial presented an issue relating to the validity of one or more claims that was not previously considered during the prosecution of the patent" [sic].7 In answering the question before it, the Board was ultimately of the view that the prior art defects alleged by Provincial were the same or very similar to those raised by the patent examiner during the prosecution of the '348 patent and did not raise a substantial new question of patentability, and thus declined to re-examine the '348 Patent.8
Regarding the question before the ONSC, the ONSC noted that the court's task was to determine whether the prior art defects alleged in the Action, which were the same as the defects alleged by Provincial in the Request, along with others considered by the Examiner, rendered the patent invalid.
The ONSC ultimately dismissed Zacon's motion, reasoning that "[a] request for re-examination that is denied because it raises no new substantial question surely does not make the initial examiner's determination infallible and unchallengeable. Similarly, a finding by a re-examination board that, having regard to a substantial new issue raised, all claims in the patent are confirmed to be patentable surely does not usurp the court's ability to determine the validity of the patent."9
Takeaways
The Court's Decision provides the following takeaways:
- The examination and re-examination processes are directed
specifically towards the issue of patentability. As stated by the
ONSC:10
- Section 86 of the Patent Rules, SOR/2019-251 (the "Rules") requires the examiner to determine if there are reasonable grounds to believe that an application for a patent complies with the Act and the Rules.
- Section 48.2 of the Act requires the re-examination board to determine "whether a substantial new question of patentability ... is raised."
- The Act reserves the issue of validity of an issued patent to
the court. As stated by the ONSC:11
- Section 59 of the Act provides that the defendant in an action for infringement of a patent may plead as defence any fact or default which by the Act or by law renders the patent void.
- Section 60 provides that any interested person may seek a declaration that a patent is void, by way of action in the Federal Court.
- A request for re-examination that is denied because it raises no new substantial question surely does not make the initial examiner's determination infallible and unchallengeable.12
- A finding by a re-examination board that, having regard to a substantial new issue raised, all claims in the patent are confirmed to be patentable does not usurp the court's ability to determine the validity of the patent.13
- It is not an abuse of process for defendants to raise an invalidity defence in a court proceeding.14
It is worth noting that a patentee may propose claim amendments or new claims in the context of a re-examination proceeding, provided that the proposed amendments do not enlarge the scope of a claim of the patent.15 On the other hand, the validity of a patent is for the court to decide, and unlike a re-examination proceeding, the court process does not afford the patentee the opportunity to amend the patent.
Footnotes
1. RRO 1990, Reg 194.
2. Paragraph 8 of the Court's Decision.
3. Under Section 48.2(3) of the Act, where a re-examination board has determined that a request for re-examination does not raise a substantial new question affecting the patentability of a claim of the patent concerned, the board shall so notify the person who filed the request. The decision of the board is final for all purposes and is not subject to appeal or to review by any court.
4. Ibid.
5. Paragraph 19 of the Court's Decision.
6. Paragraph 22 of the Court's Decision.
7. Paragraph 21 of the Court's Decision.
8. Ibid.
9. Paragraph 29 of the Court's Decision.
10. Paragraph 24 of the Court's Decision.
11. Paragraph 25 of the Court's Decision.
12. Supra note 9.
13. Supra note 9.
14. Conclusion of the Court's Decision.
15. Section 48.3(2) of the Act.
The foregoing provides only an overview and does not constitute legal advice. Readers are cautioned against making any decisions based on this material alone. Rather, specific legal advice should be obtained.
© McMillan LLP 2025
