Canadian patent law has an odd deference asymmetry.
Consider a Commissioner of Patents deciding whether an applicant exercised “due care” after missing a maintenance-fee deadline. A court tasked with reviewing that decision would generally ask whether the Commissioner’s decision was reasonable.
Contrast this with a scenario where a patent examiner has already considered prior art that later reappears in an invalidity dispute: Canadian courts generally give such technical work little comparable weight.
Arguably, the Commissioner and patent examiners have more expertise in prior art analyses than general questions of mixed fact and law; and vice versa for the courts. Yet it is the technical expertise that is largely ignored by the Canadian judiciary.
In contrast, U.S. courts generally give more deference to a patent examiner’s conclusions with respect to prior art. It may be worthwhile to consider whether a re-evaluation of the Canadian approach is in order.
Vavilov, Judicial Review, and Invalidity
The Supreme Court of Canada (“SCC”) has highlighted the importance of granting deference to the findings of administrative decision-makers on matters outside of a court’s juridical expertise. In Canada (Minister of Citizenship and Immigration) v. Vavilov, the SCC described this as “respectful attention to a decision maker’s demonstrated expertise”.[i] While Vavilov dealt with judicial review, recent Federal Court decisions have characterized the judicial role in patent invalidity cases such that the Vavilov principle simply doesn’t apply.
In fact, the Federal Court has expressly rejected the suggestion that greater deference was owed to an examiner’s decision, as judicial determinations of invalidity are not judicial reviews of Commissioners’ patentability determinations — they are instead an independent analysis.[ii] This demarcation is justified by reference to the Patent Act itself, which distinguishes patentability from invalidity and reserves validity questions for the court.[iii]
While this conclusion may flow logically as a matter of statutory interpretation, it is less clear why patentability should be distinguished from invalidity. It would seem to be common sense that an invalid patent is not patentable and an unpatentable patent is invalid. Treating them as independent questions may be more a linguistic distinction than a practical one.
The U.S. Approach
In contrast to the Canadian judiciary, U.S. courts generally show more deference to the conclusions of the patent examiner. The U.S. Court of Appeals for the Federal Circuit described this deference as what is “due to a qualified government agency presumed to have done its job.”[iv]
This “high burden” requires “clear and convincing evidence”, particularly when overturning an examiner’s findings on prior art. [v] Under U.S. jurisprudence, “persuading a fact finder that an expert agency is incorrect on a proposition is likely to be a greater forensic challenge to the advocate than showing the proposition to be incorrect in the absence of a contrary expert-agency determination.”.[vi]
Thus, U.S. courts offer more deference to examiners, despite the fact that a “presumption of validity” ostensibly exists in Canada as well.
Presumption of Validity and the Burden of Proof
Both s. 43(2) of the Patent Act and s. 282(a) of Title 35 of the United States Code[vii] set out a presumption of validity for issued patents.[viii] But in Canada, this presumption is characterized as a “weak one”.[ix]
In Canada, allegations of invalidity against an issued patent must only be proven on the “balance of probabilities”.[x] In contrast, and as discussed above, the U.S. burden is one of “clear and convincing evidence”. This burden has also been described as one requiring proof that invalidity is “highly probable”.[xi]
Thus, in Canada the burden is “probable”; in the United States, “highly probable”.
The Cost of Less Deference
Redundant analyses and analytical “do-overs” increase the costs of patent protection in time and treasure. In fact, these costs are increasing in Canada, making patents and patent enforcement more difficult and less appealing.
While the U.S. approach of requiring “clear and convincing evidence” may be a swing too far in the opposite direction, it would not take a substantial rethink of Canada’s statutory regime and jurisprudence to move the needle further toward deference. There is little preventing courts from placing more weight on a patent examiner’s conclusions when it comes to prior art.
With Canada looking internationally for new trade and investment, reducing redundant prior art analyses may be a simple step toward securing innovation and opportunity.
[i] Canada (Minister of Citizenship and Immigration) v. Vavilov, 2019 SCC 65 at para. 93.
ii] See Pollard Banknote Limited v. BABN Technologies Corp., 2016 FC 883 at para. 129.
iii] See Zacon Limited v. Provincial Doors Inc., 2025 ONSC 2954 at paras. 23-29.
iv] Pharmastem Therapeutics, Inc. v. Viacell, Inc., 491 F.3d 1342, 1366 (Fed. Cir. 2007) .
v] Sciele Pharma Inc. v. Lupin Ltd., 684 F.3d 1253 at 1259-62 (2012).
vi] Intercontinental Great Brands, LLC v. Kellogg North America Co. (Fed. Cir. 2017), 869 F.3d 1336 at 1350
vii] Specifically, 35 U.S.C. § 282(a).
viii] Section 43(2) of the Canadian Patent Act reads “After the patent is issued, it shall, in the absence of any evidence to the contrary, be valid and avail the patentee and the legal representatives of the patentee for the term referred to in section 44 or 45 and, if applicable, for the additional term granted under section 46.1”. While 35 U.S.C. § 282(a) reads “A patent shall be presumed valid. Each claim of a patent (whether in independent, dependent, or multiple dependent form) shall be presumed valid independently of the validity of other claims; dependent or multiple dependent claims shall be presumed valid even though dependent upon an invalid claim. The burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity.” While the language is not equivalent, no Canadian court has explicitly compared the two provisions to explain what words justify the differing presumptions.
ix] Zacon Limited v. Provincial Doors Inc., 2025 ONSC 2954 at para. 28, citing Apotex Inc. v. Wellcome Foundation Ltd., 2002 SCC 77.
x] Whirlpool Corp. v. Camco Inc., 2000 SCC 67, para. 75.
xi] See Colorado v. New Mexico, 467 U.S. 310 at 316 (Supreme Court of the United States).
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