An Unexpected Infringement: There and Back Again

On March 16, 2015, Justice Barnes held that AstraZeneca’s Patent No 1,292,693 (“’693 Patent”), a formulation patent for omeprazole, was valid and infringed by Apotex (2015 FC 322). This decision represents the latest entry in the 22-year old cross-jurisdictional Omeprazole saga between AstraZeneca and Apotex. Because the proceedings were bifurcated, a separate reference for damage calculations is scheduled for January, 2017 (Ontario Federal Court Hearing List).

Although this decision primarily turned on the facts, there are some notable points of interest for infringement, claims construction and expert evidence.

The Invention

Omeprazole decreases gastric acid secretion by inhibiting proton pumps. Thus, omeprezole is useful to treat a variety of conditions associated with low stomach pH such as dyspepsia, peptic ulcer disease and gastroesophageal reflux disease.

The activity of omeprazole was known at the time of patent filing, however, the instability of the compound posed challenges to commercialization. Omeprazole had to be stable under two distinct conditions: (1) when exposed to gastric acid and (2) for storage. Unfortunately, traditional enteric coats, which would provide gastric acid resistance, would also react with the omeprazole core to cause degradation under storage conditions.

AstraZeneca solved the stability conundrum in the ‘693 patent through “an inert sublayer … disposed on said core region” (see e.g. Claim 1). By separating the omeprazole core from the enteric layer with a subcoat, degradation could be avoided, permitting stable storage.

The Issue

The Apotex omeprazole formulation also contained a subcoat between the omeprazole core and the enteric coat. However, this subcoat was the product of an in situ reaction between the omeprazole core and the enteric coat. This method for creating a subcoat was not contemplated by the patentee at the time of patent application.

Does the scope of the claims capture products that result from an unanticipated method of production?

Justice Barnes held that for novel product claims, the scope of the claims are not limited to the methods identified or contemplated by the patentee [182]. Furthermore, Justice Barnes rejected the notion that a patentee has any obligation to teach its competitors how to avoid infringement [185]. Therefore, infringement does not require either party to be able to anticipate the infringement prior to the act. Such a legal conclusion is well grounded in the strict liability nature of patent infringement.

Claim Construction

Given that the method of infringement need not be anticipated, infringement in this case hinged on the meaning of “inert” and “disposed upon”. Through the assistance of expert witnesses, Justice Barnes preferred the nuanced approach to construe “inert” to mean the absence of “reactions that adversely affect the functionality of the formulation” [194]. Expert witnesses, however, provided no assistance to the construction of “disposed upon”, as this was not a term of art in the world of the formulator [170]. Absent a clear meaning to a formulator, Justice Barnes held that “disposed upon” does not signify a process limitation [189].

Of general interest, Justice Barnes cautioned against “the danger of relying too heavily on the disclosure as an interpretive guide to claim language”. In the disclosure, the patentee contemplated direct application of the subcoat layer to the omeprazole core. However, this statement in the disclosure cannot be read into the claims as process limitation when there is no language in the claims to support such a limitation [179].

The ‘693 Patent was previously and similarly construed by Justice Rothstein for a unanimous Federal Court of Appeal in Apotex Inc v AB Hassle, 2003 FCA 409, in the context of a PM(NOC) proceeding between the same parties. While PM(NOC) decisions are not binding for subsequent infringement actions, Justice Barnes held that the construction taken by FCA to “carry some persuasive weight”, especially where the issue of construction does not require specialized knowledge [175].

Patent Infringement

There was little dispute that the Apotex formulation contained a subcoat. Rather, the issue of infringement turned on whether that sublayer was continuous or inert. These issues were resolved largely through technical evidence produced by the expert witnesses.

Expert witnesses for both parties provided diametrically opposing opinions on whether there was structural continuity in the subcoat. Justice Barnes preferred the evidence offered by the AstraZeneca witness, suggesting that the subcoat was continuous [342]. Furthermore, given the fact that the subcoat swells in the presence of water, any gaps that appear when the capsule is dry may very well be sealed once the capsule gets wet [312]. AstraZeneca’s witness also produced data that ruled out the likelihood of significant quantities of omeprazole degradants or other reactive compounds in the Apotex subcoat [364].

Justice Barnes took particular note of the fact that Apotex’s experts chose to attack the experimental methodology and limitations of AstraZeneca’s expert, rather than conduct their own independent tests [298]. In particular, Justice Barnes noted that “[a]n argument that other tests or controls could have been used loses much of its strength where a party chooses not to employ those same suggested methods in its own responding analysis to see if the results differ” [361].

This approach to resolving conflicting expert opinion is consistent with the law of burdens of proof and general approach to ascribing weight to evidence. AstraZeneca had both the persuasive burden and evidentiary burden on the issue of infringement. By adducing evidence to the satisfaction of Justice Barnes, AstraZeneca had discharged its evidentiary burden to raise the issue of a continuous subcoat. Whether AstraZeneca had met its persuasive burden depended on the reliability of the evidence and the cogency of the interpretation of the data. Apotex’s decision to challenge the data meant that the scope of the dispute for infringement was on the reliability of the evidence. It is therefore logical that Apotex’s argument would lose considerable force because those attacking experimental methodologies and limitations “should not benefit from any uncertainty that could easily have been dispelled” [348].

Lou Chang is a JD Candidate at Osgoode Hall Law School and a fan of JRR Tolkien.