Making waves: Federal Court of Appeal clarifies patent overbreadth and territorial limits

In ProSlide Technology Inc. v. WhiteWater West Industries, Ltd.¹, the Federal Court of Appeal addressed several important issues in Canadian patent law, including recurring doctrinal questions related to overbreadth and utility, as well as the territorial scope of infringement—a topic at the forefront of Canadian intellectual property jurisprudence more generally. The decision offers significant guidance for patent applicants drafting specifications and for Canadian businesses engaged in design activities for products manufactured abroad.

What you need to know

• Overbreadth remains firmly entrenched as a ground of invalidity, including claims broader than the invention made. But inventor testimony and development history cannot override explicit statements in the patent specification as to what features or variations were contemplated at the time of filing. The specification itself remains the most reliable and timely indicator of what the inventor contemplated.
• Design and development activities in Canada are not enough to infringe. Patents claiming physical objects are not infringed if they are made, assembled, and used entirely outside Canada. Inventors should therefore secure patent protection in key manufacturing and commercial jurisdictions.
• Sound prediction of utility does not require disclosure of all testing. The Court affirmed that the standard for assessing utility is low, but deferred the long-standing question of whether the patent specification needs to contain extra disclosure if the utility is not proven as of filing, but rather soundly predicted.

Background

ProSlide and WhiteWater are the two largest competitors in the global market for water slides, both based in Canada. ProSlide asserted three related patents entitled "Water Ride", which describe water slide rides and features. Each patent named ProSlide’s CEO as the inventor.   

The Federal Court had concluded that the asserted claims were invalid for overbreadth and not infringed by WhiteWater, while finding the patents were not invalid for lack of utility. ProSlide appealed the overbreadth and infringement findings, while WhiteWater cross-appealed on utility.

The Court of Appeal restores claims invalidated for overbreadth

The Federal Court had held that multiple asserted claims in ProSlide’s “Water Ride” patent family were invalid for overbreadth because they omitted elements the Court viewed as key aspects of the invention made. On appeal, ProSlide challenged both the doctrine itself and its application.

The Court of Appeal affirmed that claiming more broadly than the invention that was made is a valid and well‑established ground of invalidity. However, it held that the Federal Court erred in its application of the doctrine. Specifically, the Court emphasized that determining what the inventor “made” or contemplated cannot be divorced from the patent specification, which represents the inventor’s considered statement of the invention as of the filing date.

Because the patent specifications expressly described the allegedly 'key' features as optional or variable, the Court of Appeal concluded that the Federal Court had placed undue weight on inventor testimony and expert evidence that was untethered from the disclosure. Specifically, the Federal Court had relied on testimony from the inventor regarding what he contemplated during the development of the patented product prior to filing the patent application, along with expert testimony as to how a skilled person would understand that development work.

The Federal Court identified four "key aspects" of the invention based on that testimony and expert evidence, and concluded that the claims were overbroad for omitting one or more of these features. However, the Court of Appeal found that each of these features was explicitly described in the patent specification as optional or variable, and the Federal Court failed to reconcile its conclusions with these express statements. As a result, the finding of overbreadth was set aside, and the claims were restored.

No infringement where physical making and use occur entirely abroad

ProSlide also advanced a novel infringement theory, arguing that WhiteWater’s extensive design, engineering, and development activities in Canada amounted to “making” or “using” the patented invention, even though all physical manufacture, assembly, and use occurred outside Canada.

The Court of Appeal rejected this argument. It confirmed that where claims are directed to physical objects, infringement requires activities related to the object itself—such as making, constructing, or using that object—within Canada. Generating detailed designs, drawings, and specifications in Canada, without any physical embodiment in Canada, does not meet this threshold.

The Court declined to import the “real and substantial connection” test from copyright jurisprudence, under which infringement may be found where activities constituting the infringement take place partly in Canada and partly abroad (such as where a transmission originates abroad but is received here) into patent law. The Court noted that any expansion of patent infringement standards in response to evolving technologies is a matter for Parliament, not the courts.

Sound prediction of utility upheld

On cross-appeal, WhiteWater argued that the patents were invalid for lack of utility, asserting that the specifications failed to adequately disclose the factual basis and line of reasoning supporting ProSlide's prediction of utility. 

The Court of Appeal disagreed, affirming the Federal Court's conclusion that the patents met the requirements for sound prediction. The Court reiterated that only a “scintilla of utility” is required, and that patentees are not required to disclose all testing performed, particularly where the disclosed embodiments are operable and non-speculative. On the evidence, the Court found no palpable and overriding error in the Federal Court's assessment. Notably, the Court of Appeal did not resolve the legal question of whether a heightened disclosure standard applies to sound prediction, as the patents satisfied any disclosure standard.

Implications

This decision provides important guidance for patent holders and accused infringers operating across borders. For patentees, the case confirms that Canadian patents cannot reach foreign manufacturing activities, even where substantial design work occurs domestically—a significant limitation in an era of global supply chains and outsourced manufacturing. Companies should consider obtaining patent protection in jurisdictions where physical manufacturing and use will occur. For patent applicants, the decision reinforces the importance of carefully drafting specifications to reflect the full scope of contemplated embodiments, as the specification will be a key reference point in any overbreadth challenge. The Court's affirmation of a low utility threshold and flexible disclosure requirements for sound prediction will be encouraging for patentees, but a firm statement on the so-called heightened disclosure requirement for sound prediction will have to wait for another case.