On January 22, 2026, the Federal Court of Appeal (per Locke J.A, Roussel J.A., and Goyette J.A.) (“FCA”) upheld the Federal Court’s (“FC”) ruling that certain claims in AP&C ADVANCED POWDERS & COATINGS INC.’s Canadian Patents Nos. 3,003,502 and 3,051,236 (collectively, the “AP&C Patents”) were ambiguous and therefore invalid. This decision is notable for at least two reasons: (1) the FCA did not take the opportunity to provide clarity on the standard of review; and (2) findings of ambiguity are exceptionally rare in patent cases.
AP&C Advanced Powders & Coatings Inc. v. Tekna Plasma Systems Inc., 2026 FCA 13
Background
The AP&C Patents each contain claim elements directed to a “depletion layer” at the surface of metal powder particles useful in additive manufacturing. Additive manufacturing in this context, commonly called 3D printing, creates three-dimensional objects by depositing a layer of fine metal powder then fusing the metal powder before adding the next layer. At trial, the FC held that a person of ordinary skill in the art would have understood the term “depletion layer”, but would not have understood how to measure or identify some of its essential parameters. As such, a person of ordinary skill in the art would not understand the boundary of the asserted claims or be able to determine whether they were infringing those claims. The FC found those claims ambiguous and therefore invalid. Read our blog on the FC decision here.
AP&C appealed to the FCA arguing that the FC erred in effectively requiring that a valid (unambiguous) patent claim must include means of proving infringement.
The Federal Court of Appeal’s Decision
The FCA dismissed AP&C’s appeal, with costs.
Standard of Review
Claim construction is an issue of law and is reviewable on a standard of correctness. This means that trial judges are not entitled to deference on how they construe patent claims. This has been settled law in Canada since 2000 (Free World SCC and Whirlpool SCC). Nonetheless, in 2015 (Cobalt v. Bayer), the FCA questioned the wisdom of this approach – and offered “certain observations for the Supreme Court to consider in a future case” – because claim construction almost always depends on factual findings and assessments of expert evidence which are usually entitled to deference. Since that time, the FCA has said repeatedly – without any subsequent guidance from the SCC – that the FC is “entitled to deference in its appreciation of the evidence, particularly the expert evidence, which affects the construction”, including “the appreciation of expert evidence as to how a POSITA would understand the claims” and “what common general knowledge was available to the POSITA at the date of publication”. This has effectively transformed the question of patent construction from a pure question of law (per Whirlpool SCC) into a question of mixed fact and law in which the FCA applies a correctness standard to the extricable legal issue (i.e., construction) and gives deference to the various evidentiary inputs that underlie this determination.
In the present case, claim construction was the central issue on appeal. While this may have been an opportune time for the FCA to comment on the standard of review, it did not do so. Rather, in very brief reasons, the FCA glossed over the issue and held that the appeal should be dismissed on any standard of review (correctness or deference) because there was “no error of law, no palpable and overriding error of fact, nor any error of mixed fact and law from which an error of law is extricable”.
Ambiguity
Ambiguity is a rare finding in Canada because courts always try to give meaning to a patent claim. As the late Justice Hughes remarked in 2005, “[t]here is a temptation, particularly in hotly contested cases, to throw up one’s hands and say that the claim is not capable of any construction, or any one construction.” Nonetheless, “Canadian courts have resisted holding claims to be incapable of meaning” even if they are not “a model of concision and lucidity” because “ambiguity is truly a last resort, rarely, if ever, to be used.” The last significant case in which a patent claim was held to be ambiguous was in 2016, in which the FC found that a claim defied construction because two of its elements were mutually exclusive.
In the present case, the FC judge held that the claims at issue were ambiguous because a person of ordinary skill in the art, reading the patent as a whole in light of the common general knowledge, would not have been able to determine the boundaries of the claim. This finding was upheld on appeal. The FCA held that members of the public must be able to determine where they can go with impunity, and that “when the claims…do not permit the skilled reader to understand what falls within the claim and what does not, the patent does not serve its notice function” and constitutes a “public nuisance”.
Conclusion
The FCA dismissed the appeal with costs. AP&C has 60 days from the decision to seek leave to appeal to the Supreme Court of Canada.