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Analysing the “Core of the invention” in overbreadth and utility

The Federal Court in NCS Multistage Inc. v. Kobold Corporation, 2023 FC 1486 considered the validity of five patents owned by the Plaintiff NCS Multistage Inc. and two patent owned by the Defendant Kobold Corporation, as well as infringement by each of the parties of the other’s patent(s). The Court ultimately held NCS’s patents invalid and not infringed by the Defendants Kobold or Promac Industries Ltd. It further found one of Kobold’s patents valid and infringed by NCS (the second patent having been dropped).

This blog post focuses on the Court’s analysis whether NCS’s Canadian Patent No. 2,820,704 was invalid for overbreadth or lack of utility. Other portions of the decision are addressed in other blog posts: inventive concept, double patenting, costs, and mootness.


Kobold asserted that certain claims of the 704 Patent were invalid for overbreadth because the patent did not teach how to make the invention (a fracturing valve) without certain core components, including a seal, a wedge, an equalization plug, an alignment mechanism, and holding the mandrel stationary.

The Court acknowledged that “an overbreadth analysis must not revive the ‘promise of the patent’ doctrine” and that “the search for the missing essential element must not morph into an inquiry into the achievement of the invention’s objectives” (citing Seedlings Life Science Ventures, LLC v Pfizer Canada ULC, 2020 FC 1 at para 173). It then analyzed each of the components and addressed whether:

  1. They are at the core of the invention actually invented or disclosed; and,
  2. The components formed part of the CGK of the skilled person.

The Court found that a wedge did not go to the very core of the 704 Patent, but rather that “a solid component is required to block the throughbore of the tubular” claimed by the patent. Consequently, the Court considered “whether the skilled person would understand that a solid component is required to block the throughbore of the tubular,” and found “the skilled person would know that an obstruction is inherently included in the skilled person’s understanding of a fracturing valve.” In other words, the claims that did not specify a wedge did not fail for overbreadth because this element did not go to the very core of the invention, and because the skilled person would read an obstruction into the claims for a “frac valve” based on their common general knowledge.

With respect to seal(s), equalization valve or plug, alignment mechanism, and holding the mandrel stationary, the Court found that each of these components went to the very core of the 704 Patent. It therefore analyzed whether the skilled person would construe the claims to include these components based on their common general knowledge and found they would not.

The Court rejected NCS’s arguments that claims without an equalization plug or alignment mechanism were valid to the extent that the invention was only used for well-cleaning rather than fracturing. The Court referred to the disclosure of the 704 Patent to find that the “[t]he claimed invention is directed toward a fracturing valve and the core of the invention includes components required for fracturing, not cleaning.”

The Court also rejected NCS’s argument that the skilled person would read the limitations of a dependent claim (23) into an independent claim (Claim 16) or other dependent claims (Claims 18-22) based on their common general knowledge, as this approach would lead to claim redundancy and ignore the principle of claim differentiation.


The Court then found certain claims invalid for lack of utility where they failed to include certain core components of the invention considered above (i.e. seal(s), equalization valve or plug, and alignment mechanism).

Utility must be related to the invention’s subject matter; and, “[a]lthough a ‘scintilla of utility’ will suffice, that scintilla must relate to the nature of the subject matter,” (citing AstraZeneca Canada Inc. v. Apotex Inc., 2017 SCC 36 at paras 53, 55). Because the asserted claims that did not include a lower seal, equalization valve or plug, or alignment mechanism would not operate as a fracturing valve, the Court found utility could not have been demonstrated at, or soundly predicted prior to, the relevant date.

With respect to holding the mandrel stationary, the Court found that Kobold had not met its burden to demonstrate inutility because there was insufficient evidence to demonstrate that the 704 Patent claims were completely inoperable without this feature. In any event, as noted above, the Court found Claims 16 and 18-22 invalid for overbreadth because claims with “no limitation on whether the mandrel is stationary or sliding,” were “beyond the scope of the 704 invention” because “the inventors […] only disclosed and invented a fracturing valve whereby the mandrel is stationary.”

A copy of the decision can be found here.