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Background
In ProSlide Technology Inc. v. WhiteWater West Industries, Ltd., 2026 FCA 59, a unanimous Federal Court of Appeal partially allowed ProSlide's appeal and dismissed WhiteWater's cross-appeal. The parties are global competitors in the water slide market. The dispute concerned three related patents — Canadian Patent Nos. 2,951,552, 3,063,073 and 3,085,150 (the 552 Patent Family) — all filed March 3, 2015 and covering water slide ride features.
In the underlying decision, the Federal Court (2024 FC 1439) found the Plaintiff’s (ProSlide) asserted claims invalid for overbreadth — holding they claimed subject matter broader than the invention made. The Federal Court also found that the defendant (WhiteWater) did not infringe the asserted claims because WhiteWater's physical manufacturing occurred entirely outside Canada.
On appeal, the FCA considered issues of overbreadth, infringement, and utility. The FCA upheld the Federal Court’s finding of non-infringement and sound prediction, but overturned its finding of overbreadth, restoring the validity of the ProSlide claims.
Overbreadth: Alive but reigned in.
The FCA reaffirmed that overbreadth remains a proper ground of invalidity1,2.
However, the Court of Appeal found the Federal Court erred in its assessment of overbreadth by focusing on pre-filing inventor and expert testimony without adequately engaging the patent specification. The Court of Appeal emphasized that the specification is an explicit statement of the invention by the inventor at the filing date and is therefore ordinarily the most reliable evidence of the invention made or contemplated3. The four "key aspects" the Federal Court identified as essential to the invention made were expressly described in specifications as non-essential. Those statements could not be disregarded in favour of pre-filing evidence leading the Court to reverse the overbreadth finding4.
Takeaway: overbreadth remains a valid ground of invalidity — but the specification governs. Courts assessing the invention made must engage with the patent specification. Explicit statements that features are non-essential or that contemplate specific variations will weigh heavily in the overbreadth assessment.
Infringement: Designs, CAD files, and development activities not sufficient to establish infringement of product claims.
ProSlide argued that WhiteWater’s design and development activities in Canada amounted to “making” or “using” in order to establish infringement under the Patent Act. It was undisputed that there was no physical manufacturing, assembly, or use in Canada.
The Court of Appeal affirmed the lower court’s decision, rejecting ProSlide’s novel infringement theory. The asserted claims were all directed to a product (waterslide). The Court of Appeal held that generating drawings, CAD files, and other design files could not satisfy the threshold for “making” or “using” claims to a product. Further, the FCA declined to import the "real and substantial connection to Canada" test from copyright law into the patent context, which allows infringement to be grounded on the basis of infringing activities that only partly take place in Canada5.
Importantly, the Court of Appeal distinguished the present case from other cases where preparatory steps such as assembly of the infringing product for testing in Canada occurred. The key distinguishing feature was that WhiteWater did not manufacture or assemble any physical components in Canada and, therefore, did not physically “use” or “make” any of the claimed slide components.
Takeway: the scope of product claims may not protect against design and development activities. Sophisticated design and development activities in Canada do not infringe a patent to a physical product where manufacturing and use of the physical object occur abroad.
Utility: Is explicit disclosure necessary to establish sound prediction?
The FCA upheld the lower court’s utility finding that the claims were soundly predicted.
WhiteWater argued the Federal Court erred in its assessment of the “disclosure” requirement because the patent disclosed little of ProSlide’s testing to confirm the utility of the claims. The FCA held this was not an error because the threshold for sound prediction is not high, agreeing with the lower court’s observation that “[t]he features claimed are shown not to be fanciful, inoperable, or speculative.” Further, the Court of Appeal held that it is unnecessary to disclose all of ProSlide's testing, including safety or enjoyment-related work, since the claims were only directed to a rider entering, traversing and then exiting the slide feature.
Takeaway: sound prediction does not necessarily require disclosure of all testing methods. Further, whether sound prediction requires heightened disclosure of the factual basis and line of reasoning — and whether this is confined to the pharmaceutical context — was left unresolved.
Footnotes
1 Proslide Technology Inc. v. Whitewater West Industries, Ltd., 2026 FCA 59 (ProSlide) at para. 30 citing Seedlings Life Science Ventures, LLC v. Pfizer Canada ULC, 2021 FCA 154 and Western Oilfield Equipment Rentals Ltd. v. M-I L.L.C., 2021 FCA 24.
2 ProSlide at para. 31 citing Milller v. Canada (AG), 2002 FCA 370.
3 ProSlide at paras. 35-37.
4 ProSlide at para. 37.
5 ProSlide at para. 44 citing Society of Composers, Authors and Music Publishers of Canada v. Canadian Assn. of Internet Providers, 2004 SCC 45.
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