Patentability vs. Validity: What’s the Difference in Canadian Patent Law?
When is an invention truly protected—and when can that protection be challenged?
These questions lie at the heart of Canadian patent law, and a recent Ontario Superior Court decision, Zacon Limited v. Provincial Doors Inc., 2025 ONSC2954 offers a clear and practical answer.
In this post, we’ll explore the difference between patentability and validity, why it matters to inventors and businesses, and how the court clarified the roles of the Patent Office and the judiciary in determining the strength of a patent.
What Is Patentability?
Patentability refers to whether an invention meets the legal requirements to be granted a patent in the first place. Under the Canadian Patent Act, an invention must be:
- Novel (new and not previously disclosed)
- Useful (it must work as intended)
- Inventive (not obvious to someone skilled in the field)
Before a patent is granted, a patent examiner reviews the application to ensure it meets these criteria. If the examiner finds issues, the applicant can respond or amend the application. If the application is ultimately rejected, the applicant can appeal to the Patent Appeal Board and, if necessary, to the Federal Court.
What Is Validity?
Validity, on the other hand, comes into play after a patent has been granted. A patent is presumed valid once issued, but that presumption can be challenged in court.
There are two main ways to challenge a patent’s validity:
- As a defence in an infringement lawsuit (under section 59 of the Patent Act)
- Through a separate action in Federal Court seeking a declaration that the patent is invalid (under section 60)
Unlike patentability, which is assessed by the Patent Office, validity is determined by the courts.
The Case: Zacon Limited v. Provincial Doors Inc.
In this case, Zacon Limited sued Provincial Doors Inc. and others for infringing its patent on “Balanced Ventilation Doors.” The defendants responded by claiming the patent was invalid due to anticipation and obviousness—two common grounds for invalidity.
But here’s where things got interesting.
Before the lawsuit, Provincial had already requested a re-examination of the patent by the Patent Office. The Re-Examination Board found that the request did not raise a substantial new question of patentability, and therefore declined to re-examine the patent. That decision was final and not subject to appeal.
Zacon argued that since the Patent Office had already rejected the challenge, the defendants should not be allowed to raise the same issues again in court. They claimed this was an abuse of process.
The Court’s Decision: Patentability ≠ Validity
Justice R.D. Gordon disagreed with Zacon. From his ruling we conclude that:
- The re-examination process deals with patentability, not validity
- The Patent Act clearly assigns the issue of validity to the courts
- Even if the Patent Office finds a patent to be patentable, that doesn’t prevent a court from later finding it invalid
In other words, just because a patent was granted and survived a re-examination doesn’t mean it’s immune from legal challenge.
Justice R.D. Gordon stated that:
“Even if I was to find that the request for re-examination decision addressed the question of validity of the patent, I am of the view that it is not an abuse of process to allow these defences to be pleaded and determined in this action. I come to this conclusion because the Act draws a distinction between “patentability” and patent “validity”. It clearly provides that the patentability of an invention is to be determined through the examination and re-examination process. It just as clearly provides that patent validity is to be determined by the court. If the Act dictates that patent validity is within the sole purview of the court, it cannot be unjust to allow the defences to stand.”
The court emphasized that the Patent Act creates two separate tracks:
- Patentability: handled by the Patent Office through examination and re-examination
- Validity: handled by the courts through litigation
This distinction ensures that inventors get a fair chance to protect their innovations, while also allowing others to challenge weak patents that may have slipped through the cracks.
Why This Matters to You
If you’re an inventor or business owner relying on a Canadian patent, this case highlights a few key takeaways:
- Getting a patent is just the beginning. Even after it’s granted, your patent can be challenged in court.
- Re-examination isn’t the final word. A failed re-examination request doesn’t prevent someone from raising the same issues in litigation.
- Prepare for both administrative and legal scrutiny. Strong patents are those that can withstand challenges both at the Patent Office and in court.
Final Thoughts
The decision in Zacon Limited v. Provincial Doors Inc. makes it clear: patentability and validity are not the same thing. While the Patent Office decides whether an invention deserves a patent, only the courts can ultimately decide whether that patent will hold up under legal challenge.
Understanding this distinction is crucial for anyone navigating the Canadian patent system. Whether you’re filing a new application or defending an existing patent, knowing where and how your rights can be tested will help you protect your innovation more effectively.
Want to Read the Full Case?
You can access the full decision of Zacon Limited v. Provincial Doors Inc. here.
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Updated October 2025
