Executive Summary: Key Legal and Evidentiary Issues

• Overbreadth was the central validity issue: whether claiming more broadly than the invention made (as distinct from the invention disclosed) is a proper ground of invalidity, and whether it was correctly applied to the asserted claims.
• Patent infringement turned on whether design and development activities carried out in Canada can infringe when the physical products are manufactured, assembled, and used abroad.
• Sound prediction of utility raised the question of whether the patent specifications properly disclosed the factual basis and the line of reasoning supporting the predicted utility.
• Appellate standards of review framed the analysis, with questions of law reviewed for correctness and questions of fact or mixed fact and law for palpable and overriding error.
• Evidence of the inventor's development work and expert testimony had to be weighed against the content of the patent specifications in determining what the inventor had actually made.
• Costs formed a separate stage of the litigation, engaging Rule 420, the question of divided success, and the appropriate quantum of a lump sum award.

Facts of the case

ProSlide Technology Inc. and WhiteWater West Industries, Ltd. are Canadian companies and the largest competitors in the global market for water slides, whose customers are mainly water, theme, and amusement parks worldwide. ProSlide sued WhiteWater for infringing four of its patents. The Federal Court (2024 FC 1439) concluded that none of ProSlide's asserted patent claims was infringed and that several claims were invalid. By the time of the appeal, one patent (Canadian Patent No. 2,778,601) was no longer in issue, leaving three related patents: Canadian Patent No. 2,951,552 (the 552 Patent), No. 3,063,073 (the 073 Patent), and No. 3,085,150 (the 150 Patent). The 073 and 150 Patents issued from divisional applications based on the parent application that issued as the 552 Patent. Collectively the "552 Patent Family," all three are entitled "Water Ride," describe water slide rides and features, share the filing date of March 3, 2015, and name Richard D. Hunter, ProSlide's President and Chief Executive Officer, as the inventor. They were issued on July 21, September 8, and November 24, 2020, respectively. ProSlide appealed the findings against it, and WhiteWater cross-appealed on the issue of utility. The appeal was heard at Ottawa on December 15, 2025, with judgment delivered on March 20, 2026 (2026 FCA 59); a separate costs decision followed on June 1, 2026 (2026 FCA 109).

Patent provisions and legal principles at issue

Section 42 of the Patent Act gives a patentee the exclusive right to make, construct, use, and sell the claimed invention, and infringement requires that such conduct occur within Canada. On overbreadth, the Federal Court had applied the principle that a claim broader than what was disclosed or what was actually invented is invalid, and it identified four "key aspects" of the invention made that it found were omitted from the asserted claims: the feature being part of a water slide (rather than any other amusement ride); the combination of a non-zero roll angle with a pitch angle of zero; a compounding outer wall; and a substantially planar surface as part of the sliding surface. On utility, the applicable framework was the doctrine of sound prediction, which under Apotex Inc. v. Wellcome Foundation Ltd. requires a factual basis for the prediction, an articulable and sound line of reasoning, and proper disclosure; the cross-appeal concerned only the disclosure component. The infringement question drew on authorities including Monsanto, Steelhead, and Domco, alongside ProSlide's attempt to import a "real and substantial connection to Canada" test from copyright cases such as SOCAN and Théberge.

The court's reasoning and analysis

Writing for the Court, Locke J.A. confirmed that overbreadth, including claiming more broadly than the invention made, remains a valid and distinct ground of invalidity, declining to depart from the Court's earlier decisions in Western Oilfield and Seedlings. He found, however, that the Federal Court erred in applying the doctrine here, because it determined what the inventor had contemplated primarily from the inventor's testimony and expert evidence about his development work, without regard to the invention as described in the 552 Patent Family. Each of the four "key aspects" was, in fact, expressly identified in the specification as not being essential, and the Court reversed the finding that the asserted claims were invalid for overbreadth. On infringement, the Court held that the Federal Court did not err. WhiteWater's Canadian activities, such as generating computer-aided designs and mechanical drawings, did not extend to physically making or using the claimed slide features in Canada, since the components were manufactured and assembled abroad. Locke J.A. treated the copyright-based analogies as ill-suited to patent law and applied Steelhead, under which the right to use a claim to a physical object is engaged only by use of that object, not its designs or drawings; the same reasoning governed "making." Any expansion of that threshold, he held, is for Parliament rather than the courts. On utility, the Court found no palpable and overriding error, holding that the specifications adequately disclosed the factual basis and line of reasoning for the predicted utility, and it declined to resolve whether a heightened disclosure requirement applies because the Federal Court had applied one and still found it met.

Ruling and outcome

The Court of Appeal allowed ProSlide's appeal in part and dismissed WhiteWater's cross-appeal, striking the paragraphs of the Federal Court's judgment that had held the asserted claims invalid for overbreadth and thereby restoring the validity of those claims, while leaving the findings of non-infringement intact. On costs, Locke J.A. rejected ProSlide's argument that success had been divided, reasoning that WhiteWater had secured the more important overarching victory of successfully defending against the infringement allegations, and he declined to apply Rule 420 or to award elevated costs. Recognizing WhiteWater's lack of success on the cross-appeal, the Court awarded only a single set of costs. WhiteWater emerged as the successful party for costs purposes, and although it had sought $175,000, the Court ordered ProSlide to pay it a lump sum of $25,000, together with post-judgment interest at a rate of 2.75%.