Jennifer Ko, Zach Nickels

The recent decision of the Federal Court in Tekna Plasma Systems Inc v AP&C Advanced Powders & Coatings Inc, 2024 FC 871 provided detailed insights into the concept of invalidity on the basis of ambiguity and patent law’s fundamental requirement that the scope of a patent’s protection be reasonably predictable and clear to the public.

Although ambiguity-based invalidity is uncommon in Canadian patent litigation, the decision serves as an important reminder of the fundamental requirement that patent claims define distinctly and in explicit terms the subject matter of the invention for which an exclusive privilege or property is claimed.

The Parties

The case concerned Tekna Plasma Systems Inc. (“Tekna”) and AP&C Advanced Powders & Coatings Inc. (“AP&C”), two parties engaged in the manufacture of metal powders used in the growing additive manufacturing industry.

The Facts

The patents at issue, Canadian Patent 3,003,502 (the “’502 Patent”) and 3,051,236 (the “’236 Patent”), were owned by AP&C and relate to production of reactive metal powders that are particularly useful in additive manufacturing. Additive manufacturing includes processes such as 3D printing where three-dimensional objects are created by depositing and solidifying materials layer by layer, as opposed to subtractive manufacturing which removes material to create objects (e.g. milling). Tekna sought declarations that the patents were invalid and not infringed. AP&C counterclaimed that Tekna’s production of titanium alloy powders infringed its patents.

Most of the claims in the patents described processes for manufacturing metal powders through gas atomization, whereby a metal source is melted and subjected to high velocity gas flow which breaks the molten metal into droplets, which later cool and solidify as powder particles. Generally, this gas atomization process creates a surface layer on the metal particles, which according to the claims of the ‘502 Patent are comprised of a depletion layer composed of atoms of the metal and atoms of the additive gas and a second native oxide layer.

Central to the claims of both of the patents was this concept of the depletion layer at the surface of the reactive metal particles. Specifically, each of the claims of the two patents included the formation of a depletion layer or a system configured to control a depletion layer’s formation as essential elements.

As such, the meaning of depletion layer and the question of whether a person of ordinary skill in the art, in light of their common general knowledge, would know whether a particle had a depletion layer by reading the patents, were central issues to the dispute.

The Court’s Findings

Key to the Court’s decision, the term depletion layer was held to not be a term of art, but as suggested by counsel for AP&C, rather a “term of patent” coined by the inventors. Accordingly, AP&C proposed a construction in which the existence of a depletion layer in a subject particle is to be determined by conducting a comparison of the oxygen concentration profile of the subject particle to that of a particle made without additive gas (the “Comparative Approach”).

By contrast, some of the claims in the ‘236 Patent explicitly set out what a depletion layer was and described when a powder particle did or did not have one, and thus the Court held these claims to be valid and rejected Tekna’s utility and overbreadth arguments concerning them. However, AP&C did not assert that Tekna infringed any of the valid claims of the ‘236 Patent, and as such, the issue of validity was determinative of the claim.

Ultimately, the Court held that neither the disclosure nor the claims of the ‘502 or ‘236 Patents instructed the reader to undertake the Comparative Approach, and that AP&C was effectively seeking to read its Comparative Approach into the disclosure before subsequently reading it into the claims of the patents. Moreover, the Comparative Approach was not even an approach that AP&C’s own expert suggested would be understood from the claims of either patent.

With the exception of the few claims in the ‘236 Patent, it was impossible for a skilled reader to know or determine whether or not a powder particle had a depletion layer as contemplated by the claims. As a result, the Court determined that the ‘502 patent was invalid and not infringed by Tekna, and that most of the claims of the ‘236 Patent were similarly invalid and not infringed.

Key Takeaway

This case serves as a stark reminder to applicants and their patent agents that while patent claims need not be perfect or a model of lucidity, and a lack of clarity or potential for competing constructions alone is not necessarily fatal, if insufficient information is included in the claims to allow the skilled person to know what does and what does not fall within the scope of the claims, it is, as characterized by the Court, “a self-inflicted wound [that] cannot be corrected by imposing or reading in new standards of reference that are not found in the patent and cannot be reasonably understood from the claim language as drafted.” In particular, patent applicants and their agents should not overlook the need to clearly define any essential terms that are “terms of patent”, coined by inventors, that are not terms of art, to mitigate the risk of the patent being invalidated for ambiguity.