Patent Re-Examination Board Decision Does Not Preclude Patent Validity Challenge In Court

On May 20th, 2025, the Ontario Superior Court of Justice in Zacon Limited v. Provincial Doors Inc., 2025 ONSC 2954 found that the validity of a patent may be challenged in court on the same grounds previously rejected by a Canadian Patent Office Re-examination Board. This decision confirms that the Court has exclusive jurisdiction to hear and decide patent “validity” challenges. Re-examination decisions by the Canadian Intellectual Property Office (CIPO) do not disturb this jurisdiction.

Background

The Canadian Patent Act does not offer a robust post-grant patent challenge mechanism before CIPO, unlike, for example, the Inter partes review procedure in the United States. Instead, parties have the ability to seek re-examination of a granted patent. At a high level, a party seeking re-examination can submit prior art to CIPO that was not considered during prosecution. CIPO can then consider whether a “substantial new question of patentability” arises from the prior