On June 7, 2024, the Federal Court issued its Judgment and Reasons in Tekna Plasma Systems Inc v AP&C Advanced Powders & Coatings Inc (2024 FC 871), finding all claims of the Defendant’s Canadian Patent No 3,003,502 (502 Patent) and most claims of Canadian Patent No 3,051,236 (236 Patent) invalid on the basis of ambiguity, and declared Tekna Plasma Systems Inc (Tekna) had not infringed either patent. This is a rare case where the majority of the claims of the two patents at issue were invalid on the basis of ambiguity. The Federal Court's comprehensive decision emphasized the importance for the public of the predictability of the monopoly claimed by a patent.
Tekna was successfully represented by Smart & Biggar litigators François Guay, Jeremy Want, Jean-Sébastien Dupont, Matthew Burt and Audrey Berteau.
Background
Tekna and AP&C Advanced Powders & Coating Inc (AP&C) both manufacture metal powders by plasma atomization, mainly for use in additive manufacturing. In basic terms, plasma atomization is a technology that produces fine spheroidal metal powders by contacting a metal wire with an atomizing fluid heated to a plasma state. The metal melts and is atomized into small liquid droplets. As the liquid metal droplets rapidly cool, they solidify into micron-sized powder particles.
Tekna was successful in obtaining a declaration from the Federal Court that most of the claims of AP&C’s patents are invalid for ambiguity and a declaration that no claims of either the 502 and 236 patent had been infringed by Tekna’s production of titanium alloy powders. Only 14 of the 147 claims of AP&C’s 236 Patent were held to be valid. Both patents are closely related, originating from the same parent application. Both patents pertain to an atomization manufacturing process which claims to improve the flowability of the resulting powder particles. All claims of both patents contain an essential element relative to the formation of a so-called “depletion layer” at the surface of the particles of reactive metal powder. The claims of the 502 patent and some claims of the 236 patent involve bringing an additive gas into contact with the metal during atomization which results in the formation of the claimed surface layer on the metal powder particles. The claims of the 502 patent and some claims of the 236 patent claim the formation of two layers at the surface of the particles: a first depletion layer and a second oxide layer.
Key findings
Construing "depletion layer”, a term coined by the inventors
This decision centers around the meaning of the term “depletion layer.” As agreed by the parties and their experts, a “depletion layer” is not a term that is generally used in the field of powder manufacturing but is rather a term coined by the inventors of the patents. Thus, the meaning of the term needed to be gleaned from the patents as it would be read and construed by the skilled reader. The Court emphasized that in determining the meaning of this term, it needed to consider and construe the language of the various claims in light of the disclosure, while not arbitrarily selecting other parts of the specification that would broaden or narrow the claims under the pretext of interpreting its terms.
AP&C’s main expert construed the term “depletion layer” without reference to the disclosure of the patent nor the common knowledge of the skilled person. He opined that the skilled person would understand the term to merely be a name the inventors ascribed to the layer without introducing any further requirements, affirming that the inventors could have named this layer anything as it is “just a name.” The Court criticized this approach, finding it made the word depletion meaningless, effectively ignoring the inventors’ choice of an additional term to describe this layer of the metal particles.
Tekna’s main expert construed the term “depletion layer,” by consulting the disclosure of the patent to better grasp the meaning of the term, as a skilled person would do in the circumstances. The Court agreed with this approach.
The meaning of the first layer “depletion layer” raised several questions. One of these questions, applicable to both patents, concerned the meaning of depletion. The Court construed the term “depletion layer” to signify a reduction in the concentration of the atoms from the additive gas through the thickness of the layer. A second question, relevant to the first claim of both patents, was whether the atoms of the additive gas had to be present in the first layer in the form of a reaction product such as a metal oxide and/or did they have to be present as a result of diffusion. The Court determined that the skilled person would not understand the component of the additive gas to necessarily be present in the “depletion layer” in the form of a reaction product between the additive gas and the reactive metal source, or to be present as a result of diffusion.
Invalidity of most claims of the patents on the basis of ambiguity
Courts have a general “disinclination to find a claim invalid for ambiguity” as patents are to be read in a way that is sympathetic to accomplishing the inventor’s purpose, with a mind willing to understand and not one desirous of misunderstanding.
A patent holder should know what they own, and the public should know what they do not. It is a fundamental principle that a patent must give to the public notice as to what is claimed and what is not; pursuant to subsection 27(4) of the Patent Act, the claims of a patent must define “distinctly and in explicit terms the subject-matter of the invention for which an exclusive privilege or property is claimed”. Otherwise, a patent claim may be found invalid for ambiguity.
Application to the 502 Patent: for the 502 Patent, each of the claims requires, as an essential element, a powder particle having a “depletion layer” that is deeper and thicker than the native oxide layer. The Court found that the claims did not allow the skilled person to know whether or not a process for producing a metal powder would be within the claims of the Patent as the skilled person would be unable to determine when a particle of metal powder has a “depletion layer” that is deeper and thicker than the native oxide layer. AP&C was not able to show how a skilled person would distinguish between the “depletion layer” and the native oxide layer, so as to confirm their existence and compare their depth and thickness even if it was assisted by three experts in the field who collectively prepared six expert reports; conducted various tests in a university and a specialized lab; and had over three years to prepare their answer.
Application to the 236 Patent: as for the 236 Patent, the majority of the claims were also found invalid for ambiguity for similar reasons. However, a few claims of the 236 Patent were found not to be ambiguous as they specified how to determine the existence of a “depletion layer” by setting out how to identify the boundaries of the “depletion layer” and defining its minimum depth (in the tens of nanometers). Thus, the Court held that a skilled person would be able to determine whether a process falls within one of these unambiguous claims.
AP&C’s arbitrary and subjective comparative testing approach
The challenges AP&C faced in demonstrating infringement further confirmed the Court's determination of ambiguity. AP&C sought to demonstrate Tekna’s alleged infringement of AP&C’s patents by testing different samples of Tekna’s powders. Instead of comparing the results of the Tekna samples to the information and data provided in the patents, AP&C chose to compare the results with hand selected AP&C samples, the majority of which post-date the filing of the patent, and that were not accessible to the public. AP&C relied on positive controls, AP&C samples prepared with additive gas, and negative controls, AP&C samples prepared without additive gas but without establishing that the positive controls had a “depletion layer.”
AP&C’s use of its own powders as a baseline for comparison with Tekna’s powders helped solidify the determination that the claims in AP&C’s patent were not sufficiently clear for a skilled person to assess whether a powder falls within the scope of the claims. AP&C’s approach to testing was rejected by the Court because the testing cannot be conducted without the patent owner, which means it does not meet the public notice function of the patent. If this methodology is the only way to determine infringement, a member of the public would have no way of determining whether they infringe the monopoly claimed in the patent.
Tekna raised insufficiency jointly with ambiguity
The Court noted the strong relationship between insufficiency and ambiguity, as both grounds of invalidity relate to whether the specification of a patent adequately defines the invention and describes how it is put into operation. Specifically, a patent claim will be invalid for insufficiency if the specification fails to teach the person skilled in the art how to put into practice all embodiments of the invention. Due to the strong overlap between the parties’ arguments for ambiguity and insufficiency, the Court determined that making an additional finding of insufficiency was unnecessary. Nevertheless, the Court stated that for both patents (except for a few claims of the 236 patent excluded from the ambiguity determination) a skilled person would be unable to put the patent into practice as they had no way to determine whether a depletion layer was produced.
Concluding remarks
This decision serves as a reminder to patentees that a patent must contain all the data and information required to establish the outer limits of their monopoly, to allow a skilled person to replicate the invention and to clearly understand the meaning of any coined terms. This decision is one of the few instances where patent claims were invalidated on the basis of ambiguity.
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