On March 20, 2026, the Federal Court of Appeal (per Locke J.A., Roussel J.A., and Heckman J.A.) (“FCA”) released an important decision in the patent dispute between ProSlide and WhiteWater, two competitors in the water slide industry. The ruling restores the validity of three of ProSlide’s patents relating to water slides but confirms that WhiteWater did not infringe any of them. The FCA’s decision provides helpful clarity on how Canadian courts treat patent scope, foreign manufacturing, and the level of disclosure required to show an invention works. It also provides further guidance on the correct approach for assessing allegations of invalidity for overbreadth.
Proslide Technology Inc. v. Whitewater West Industries, Ltd., 2026 FCA 59
Background
ProSlide and WhiteWater are the largest waterslide companies in the world. Both are based in Canada. ProSlide asserted four patents at trial. One patent, which was no longer in issue on appeal, claimed a water slide comprising a sliding surface concave about three axes. The other three patents (a parent and two divisionals) claimed various water slide features.
The FC had held the claims in ProSlide’s patents were invalid for overbreadth, finding that certain features were “essential” to the invention actually made by the inventors but were missing from the claims. Moreover, even if valid, the claims were not infringed because none of WhiteWater’s impugned articles were ‘made’ or ‘used’ in Canada.
Read our blog on the FC decision here.
ProSlide appealed to the FCA, arguing that the Federal Court erred in finding the claims of the patents overbroad and not infringed. WaterSlide cross-appealed the holding that the patents were not invalid for lack of sound prediction.
The Federal Court of Appeal’s Decision
- Overbreadth: FCA Reasserts the Doctrine, but Reverses Its Application
Although the FCA disagreed sharply with the FC’s decision that the claims at issue were overbroad, the FCA reaffirmed that the overbreadth doctrine remains good law in Canada. The FCA had recently confirmed the doctrine in its Western Oilfield (2021 FCA 24) and Seedlings (2021 FCA 154) decisions. ProSlide’s attempts to argue that the doctrine is historically dubious or doctrinally incoherent failed to meet the high bar for overturning binding precedent as set by the Supreme Court in Sullivan (2022 SCC 19).
The FCA found that the FC had incorrectly applied the overbreadth doctrine to the facts of this case. Specifically, the FC erred in finding that the claims were invalid for being broader than the invention made based on the testimony of the inventor as to what he contemplated during the development of the patented product (prior to filing the patent application), and on expert testimony as to the perspective of a skilled person concerning this development work. The FC had not considered the invention as described in the patents.
This was the key error in the FC decision. The FCA emphasized that the primary reference point for identifying the “invention made” must be the patent specification itself, not an inventor’s testimony about pre-filing thinking and not an expert’s reconstruction of that thinking. In this particular case, the features deemed “essential” by the FC for the purposes of overbreadth were explicitly indicated to be non-essential in each of the patent specifications. Because the patents contemplated variability on these non-essential aspects of the water slides, the claims could not be broader than the invention made.
- Infringement: Canadian Design Work Is Not “Making” or “Using”
Although the validity of ProSlide’s three patents was restored, ProSlide still failed to establish infringement. The FCA reconfirmed the basic tenet that patent rights are territorial and that infringement of a Canadian patent occurs only when the physical embodiment of the claimed invention is made, used, or sold within Canada. In this case, WhiteWater manufactured and assembled all allegedly infringing slide features outside Canada.
ProSlide urged the FCA that WhiteWater’s activities in Canada, namely, virtually all design and development activities short of physical manufacture, amounted to “use” of the claimed invention. ProSlide relied on copyright jurisprudence involving digital works by analogy for a more flexible approach to assessing infringement. The FCA rejected this analogy outright. Design work alone, even if substantial and performed in Canada, does not amount to infringement. To infringe a product claim, the defendant must make or use the actual physical product in Canada.
- Utility and Sound Prediction: FCA Upholds the Validity of the Patents
WhiteWater cross-appealed on utility, arguing that the claims were invalid for lack of sound prediction of utility. The FCA began by confirming the well-known three-part test for sound prediction: 1) there was a factual basis, 2) the inventors had a sound line of reasoning, and 3) proper disclosure was made.
Here, WhiteWater argued that the third requirement, proper disclosure, was not met. The FCA disagreed and held that the patent specifications disclosed a sufficient basis and reasoning for a skilled person to understand why the invention would work. There was no need to provide detailed testing data, such as rider enjoyment or safety testing, since the claimed invention concerned a slide structure, not a testing method. Finally, the FCA reiterated that only a “scintilla of utility” is required (a low threshold) and the patents contained enough information—through figures and description—that the claimed utility had been predicted through computer-aided simulations.
Conclusion
This decision is important for two reasons:
- The overbreadth doctrine lives on. However, the patent’s specification has taken on more importance when assessing the “invention actually made”. Inventor testimony and inferred pre-filing intentions cannot override the explicit language of the patent.
- Canadian patents are territorial and only provide rights in Canada. Design-stage activities taking place in Canada do not on their own amount to “making” or “using” a claimed product in Canada.
ProSlide has 60 days from the date of the Judgment to file an application for leave to appeal to the Supreme Court.