Rare Federal Court Finding: AP&C’s Two Patents Invalid for Ambiguity
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.
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. AP&C 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 generally relate to processes for manufacturing metal powders through gas atomization, although some claims of the 236 Patent relate to atomization systems rather than processes. They 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.
Claims
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.
Claim 1 of the 502 Patent claims two layers: (1) a depletion layer that is deeper and thicker than (2) the native oxide layer:
1. A reactive metal powder atomization manufacturing process comprising:
…
(d) wherein said surface layer comprises a first layer and a second layer, said first layer comprising atoms of said heated reactive metal source with atoms and/or molecules of said at least one additive gas, said first layer being a depletion layer deeper and thicker than said second layer, said second layer being a native oxide layer,
Claim 1 of the 236 Patent claims a process that involves forming a “depletion layer”:
1. A reactive metal powder atomization manufacturing process comprising:
(a) atomizing a heated reactive metal source to produce a raw reactive metal powder, wherein (b) atomizing the heated reactive metal source comprises contacting said heated reactive metal source with an atomization mixture comprising an atomizing gas and an additive gas, wherein the atomizing gas is at a greater temperature than the heated reactive metal source, and (c) forming, with said additive gas, a depletion layer including a component from the additive gas on particles of the raw reactive metal powder… The system claims of the 236 Patent claim atomization systems with various components to control formation of a depletion layer that includes a component of the additive gas.
Claims Construction
The parties did not agree on how the skilled person would understand the terms first layer and depletion layer. Justice McHaffie found that the term depletion layer in Claim 1 of the 502 Patent is not a term of art, but a “term of patent.”
To construe the terms first layer and depletion layer, the parties and their experts referred to aspects of the disclosure. Justice McHaffie found that the language of the claims, the patent disclosure, the experts’ evidence, and the parties’ submissions raised a series of questions about the first layer and the depletion layer including:
- What does depletion signify, if anything?
- Do the atoms of the additive gas have to be present in the first layer in the form of a reaction product such as a metal oxide and/or do they have to be present as a result of diffusion?
- What does the limitation that the first layer be a depletion layer that is deeper and thicker than the second layer/native oxide layer required, particularly in terms of the location, size, measurability, and nature of the depletion layer?
With respect to the first point, Justice McHaffie agreed with the Plaintiff’s expert that the POSITA would understand depletion layer to signify “a depletion/reduction in concentration of the atoms from the additive gas through the thickness of the layer.”
For the second point, Justice McHaffie refused to read into the claims the limitations that the atoms had to be present as a result of diffusion and that it has to contain a reaction product. He held that a POSITA construing Claim 1 purposively and in light of the entirety of the patent and the CKG would conclude that it does not include these limitations or requirements.
With respect to the third point, Justice McHaffie found that one of the requirements of the depletion layer was that it be “deeper and thicker than the native oxide layer” and that the terms deeper and thicker impose two separate requirements. The parties agreed that the depletion layer must be beneath the native oxide layer and therefore it is deeper. It was also understood that thicker inherently means that the depletion layer has a greater thickness than the native oxide layer.
When considering the third point, Justice McHaffie considered whether the skilled person would know how to determine the thickness of the depletion layer including where the depletion layer ends and the native oxide layer starts. The patentee attempted to import a requirement into Claim 1 that would explain how to distinguish the depletion layer from the native oxide layer. Specifically, the patentee argued that the skilled person would understand that a powder particle has a depletion layer that is deeper and thicker than the native oxide layer in accordance with Claim 1 if its ToF-SIMS oxygen concentration profile, and in particular the “tail” of the profile, is above that of a powder particle prepared without additive gas. Justice McHaffie rejected the patentee’s position and concluded that the skilled person applying a purposive approach to construction and with a mind willing to understand the patent would be unable to know whether a particle has a depletion layer that is deeper and thicker than the native oxide layer. Justice McHaffie further considered this issue when assessing ambiguity.
He therefore concluded that a POSITA would understand that the depletion layer is “a layer at the surface of the particle that (a) contains atoms from the reactive metal source and atoms and/or molecules of the additive gas, not necessarily in the form of a reaction product; (b) must be distinguishable from the native oxide layer to allow comparison with that layer; (c) is deeper than the native oxide layer in the sense of being beneath it, that is, closer to the center of the particle and starting where the native oxide layer ends; and (d) is thicker than the native oxide layer in the sense having a greater thickness when considered along the radius of the particle.
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 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 know or determine whether a powder particle has a “depletion layer” within the meaning of both patents’ claims.
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 nanometers 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.
