Co-authored by Emily Papsin
The Federal Court recently held (per McHaffie J.) that the impugned claims of two related patents for an additive manufacturing process (3D printing) were invalid and not infringed because an essential element (“depletion layer”) was ambiguous.
Tekna Plasma Systems Inc. v. AP&C Advanced Powders & Coatings Inc., 2024 FC 871
Background
This case concerned two patents relating to the production of reactive metal powders for use in additive manufacturing, or “3D printing”. The two patents had common inventors and an identical disclosure. The claims of the patents differed, but each required the formation of a “depletion layer” as an essential element.
The parties, Advanced Powders & Coatings Inc.(“AP&C”) and Tekna Plasma Systems Inc. (“Tekna”), were business competitors. AP&C owned the two patents at issue. In 2019, Tekna sued for declarations of non-infringement and invalidity, and AP&C then counterclaimed for declarations of infringement.
The trial was heard over fourteen days in late-2022 and eighteen months later, the Court rendered its 621 paragraph Judgment and Reasons, holding that each claim requiring a “depletion layer” was invalid for ambiguity and was not infringed.
Claim Construction
In Canada, claim construction is a question of law to be determined by the Court through the eyes of a skilled person and in view of that person’s common general knowledge.
The main issue in this case was the construction of the term “depletion layer” in the claims of each patent. This issue was ultimately dispositive of the validity and infringement issues raised by the parties.
Claim 1 of Canadian Patent 2,003,502 (“502 Patent”) covered a “reactive metal atomization manufacturing process” comprising the following steps:
(a) atomizing a heated reactive metal source to produce a raw reactive metal powder;
(b) contacting said heated reactive metal source with an atomization mixture comprising at least one atomizing gas and at least one additive gas that is present at a concentration of less than 1000 ppm in said atomization mixture while atomizing said heated reactive metal source; and
(c) forming, with said at least one additive gas, a surface layer on said raw reactive metal powder, said raw reactive metal powder with said surface layer thereon, comprises less than 1000 ppm of at least one element from said at least one additive gas,
(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,
(e) and wherein a particle size distribution of about 10 to about 53 μm of said raw reactive metal powder with said surface layer thereon, has a flowability less than 40 s, measured according to ASTM B213.
Claim 1 of Canadian Patent 3,051,236 (“236 Patent”) also claimed a “reactive metal atomization manufacturing process”, but did not require the “depletion layer” to be “deeper and thicker” than the “native oxide layer”:
(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,
(d) the raw reactive metal powder having a particle size distribution of 10 to 53 micrometers with a flowability less than 40 s, measured according to ASTM B213.
Tekna brought this proceeding as an impeachment and non-infringement action and AP&C counterclaimed alleging infringement of the patents at issue.Tekna alleged that the patents at issue were invalid for a number of reasons, including ambiguity.
Construction of the 502 Patent
The parties agreed that each element of the claim was essential. The primary construction issue was the meaning of “depletion layer” that was claimed to be the “first layer” of the “surface layer” of the resulting “reactive metal powder”.
The Court held that a skilled person would have understood the terms “first” and “second” to distinguish between the two layers of the “surface layer” and not to require a temporal order of their formation.
The Court also held that the skilled person would have understood the “second layer” to be the “native oxide layer” based on a purposive construction of the claims.
The construction of “depletion layer” was less straightforward. The Court held that the claim language alone was inadequate and that the term needed to be construed in light of the specification as a whole. The Court addressed several questions as part of its analysis, namely:
i) What does depletion signify, if anything?
ii) 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?
iii) What does the limitation that the first layerbe a depletion layer that is deeper and thicker than the second layer/native oxide layer require, particularly in terms of the location, size, measurability, and nature of the depletion layer?
On issue (i), the Court found that the skilled person would have understood “depletion” to mean “a depletion/reduction in concentration of the atoms from the additive gas through the thickness of the layer”. This was in line with the evidence given by Tekna’s expert (Mr. Barnes).
On issue (ii), the Court found that the skilled person would have understood claim 1 in a manner that did not require the atoms of additive gas to be present in the “depletion layer” or to require that diffusion be the operative mechanism for this to occur.
Finally, on issue (iii), the Court held that the skilled person would have understood the words “deeper and thicker” to be separate requirements, as argued by Tekna, and not simply a restatement of a single criterion, as suggested by AP&C. The Court rejected the “single criterion” construction primarily because it would have required some (but not all) aspects of the disclosure to be “read in” to the claim.
Based on this analysis, the Court held that a skilled person would not have been able to give meaning to the term “depletion layer”.
Construction of the 236 Patent
The Court found that most of the essential elements of the 236 Patent claims would have been construed by the skilled person in the same way as in the 502 Patent. On the primary construction issue, the Court held that the skilled person would not have been able to understand the meaning of “depletion layer” based on the specification as a whole.
Ambiguity of the 502 Patent
Subsection 27(4) of the Patent Act requires the claims of a patent to define “distinctly and in explicit terms the subject-matter of the invention for which an exclusive privilege or property is claimed”. A claim can be held invalid for ambiguity if this requirement is not met. The party challenging the validity of an issued patent has the burden of proof.
The Court held that the impugned claims of the 502 Patent were ambiguous because the skilled person would have been unable to determine whether they had produced a “depletion layer” that was “deeper and thicker” than the “native oxide layer”. This was consistent with the following portion of Tekna’s closing argument:
“…after more than 3 years of litigation, very complex testing in specialized labs and universities, five experts in total, hundreds of pages of expert reports, and three weeks of evidence at trial, no one has been able to tell the Court (despite the Court asking the question on a few occasions) where the oxide layer and the alleged depletion layer are on any of the test results, and how thick these two layers are.”
The 502 Patent offered no metrics for assessing the depth and thickness of the first and second layers relative to each other. The parties’ experts were unable to assist the Court by suggesting a reliable method known in the art for assessing this essential element of the claim. It would have been impossible for a skilled person to know whether they were within or outside the scope of the claims. As such, the impugned claims were held to be invalid because the terms “depletion layer” and “deeper and thicker” were ambiguous. In other words, the claims did not “distinctly and in explicit terms the subject-matter of the invention” as required by subsection 27(4).
The Court held that it was unnecessary to address Tekna’s insufficiency, inutility and overbreadth allegations in relation to the 502 Patent.
Ambiguity of the 236 Patent
For the same reasons, the Court held that the skilled person would not have been able to understand the term “depletion layer” in the impugned claims of the 236 Patent based on the specification as a whole. The claims were thus invalid for ambiguity. As such, the Court did not need to engage in a discussion regarding the claims’ insufficiency.
Infringement
The Court did not need to consider the allegations of infringement because the 502 and 236 Patents were invalid, and an invalid patent cannot be infringed. Moreover, in a case such as this, where an essential claim element could not be construed, there is no reliable way of determining whether an allegedly infringing process falls with its scope.
Nonetheless, in obiter, the Court conducted a form of infringement analysis by comparing the allegedly infringing process to the claims as construed, where possible, and to the parties’ arguments in respect of the claim element that could not be construed, i.e., “depletion layer”.
The Court turned to each parties’ experts to assist in its assessment of whether the “depletion layer” was or was not formed in Tekna’s process in the context of the tests conducted by AP&C. In analyzing the data presented, AP&C’s experts opined that two samples of Tekna’s powders had depletion layers. However, AP&C’s experts conceded that other factors during testing could have resulted in the formation of a depletion layer, demonstrating that AP&C’s conclusions were merely assumptions.
The Court also emphasized that AP&C’s analyses were based on samples from AP&C that were not accessible to the general public. The Court viewed this as AP&C attempting to create arbitrary parameters that were not set out in the 502 Patent to demonstrate infringement. The Court concluded that AP&C had failed to demonstrate that this essential element of the claims was included in Tekna’s impugned product.
AP&C further argued that the Court could extrapolate from analytical testing conducted by its experts to find that Tekna’s powders did in fact infringe the 502 Patent.
Conversely, Tekna’s experts opined that AP&C’s method of analysis was not described in the patent and rested on unsupported presumptions for which no explanations were given.
The Court relied on the decision from Bombardier Recreational Products Inc v Arctic Cat Inc and held that that it could not find infringement based on an extrapolation. The Court was not satisfied on a balance on probabilities that the samples infringed or that they were a true representation of the population of impugned products. The Court held that Tekna’s powders do not contain a “depletion layer”, as construed by the experts, and that Tekna’s activities fell outside the scope of the 502 Patent. The Court also held that AP&C had also not demonstrated infringement of any of the claims of the 236 Patent because the evidence was inconsistent and arbitrary.
Conclusion
This decision provides a good example of the tension that patent practitioners often face between drafting claims using broad language to prevent infringement, while ensuring that the claims are narrow enough to be valid. In the case of these two patents, perhaps if a definition for “depletion layer” had been provided in the specification, the claims’ validity would have been upheld, but it may also have then been easier to design around.
This decision also illustrates the difficulty of conducting testing for purposes of proving infringement (and also invalidity). Unless the patent calls for a specific test procedure to be used, it is often easy for experts to criticize the methodology used, and the conclusions that can be reached from the test data.