Federal Court depletes AP&C’s validity arguments
Two patents relating to the processes for manufacturing reactive metal powders were found invalid for ambiguity pursuant to subsection 27(4) of the Patent Act in Justice McHaffie’s recent Federal Court decision 2024 FC 871. This is one of the few cases where claims have been invalidated for ambiguity.
Parties and Patents
The plaintiff, Tekna, and the defendant, AP&C, are both manufacturers of metal powders used in additive manufacturing. AP&C owns the two patents that were at issue: CA 3,003,502 and CA 3,051,236, and alleged that Tekna’s production of titanium alloy powders infringed the patents. Tekna alleged that both patents were invalid and not infringed.
The 502 and 236 Patent are members of a patent family, share a filing date, share common inventors and have an identical disclosure. The difference between the two patents are the processes and systems claimed in their claims, however, both patents claim a “depletion layer” and/or the formation of a depletion layer. The “depletion layer” was considered to be an essential element of the claims at issue. Justice McHaffie found that the meaning of the term “depletion layer” was central to the patents and to the disputes in the action.
In particular, the 502 Patent claimed two layers: (1) a depletion layer that is deeper and thicker than (2) the native oxide layer. The 236 Patent process claims all require that the process involve forming a “depletion layer” and the system claims claim the system be “configured to control an atomizing gas in the atomizing mixture to control formation of a depletion layer.”
Ambiguity
The Patent Act requires patent claims to define “distinctly and in explicit terms the subject-matter of the invention for which an exclusive privilege or property is claimed” or else the patent may be rendered invalid for ambiguity. As Justice McHaffie reiterated, “the ultimate question is whether it is ‘impossible for the skilled person to know in advance whether or not something would be within the claims.’” (2022 FCA 142)
A claim is likely ambiguous if it uses language that is avoidably ambiguous or obscure, if the phrase at issue cannot be interpreted using grammatical rules and common sense, and if a claim can be interpreted in more than one way; keeping in mind that a claim is not invalid because it is not a model of concision and lucidity. (2022 FCA 142)
Justice McHaffie’s finding
Justice McHaffie found that it was impossible for the skilled reader to known or determine whether a powder particle has a “depletion layer” within the meaning of both patents’ claims.
Specific to the 502 Patent, Justice McHaffie found Claim 1 which distinguished between the depletion layer and native oxide layer, was ambiguous as the POSITA would not know how to assess whether the depletion layer was deeper and thicker. He found AP&C was unable to put forth a consistent and coherent explanation of how to perform the comparison between the thickness of the “depletion layer” and the “native oxide layer.” Further, AP&C’s argument that the 502 Patent disclosure provided an objective method to assess whether a particle has a “depletion layer” failed because the disclosure compared oxygen concentration profiles between particles, not thickness as set out in the claims.
Likewise, Justice McHaffie found that most of the 236 Patent process claims were ambiguous because the claims did not specify a manner of determining the existence and depth of a depletion layer. However, he found some process claims that specified the depth of the depletion layer in nm were valid. He found the 236 Patent system claims were also ambiguous because to know the scope of the claim, one would need to know what a “depletion layer” is and be able how to assess whether a system could control formation of such a layer.
The full decision can be read here.