The Federal Court of Appeal (per Locke JA.) affirmed a trial decision in which claims in Lilly’s patent covering physiologically acceptable salts of tadalafil were found to be invalid for overbreadth and insufficiency. The principal issue on appeal was the proper construction of the claim term “physiologically acceptable”, though the Court’s obiter statements regarding the legal test for sufficiency are also noteworthy.
Eli Lilly v. Apotex, 2024 FCA 72
Claim Construction
Lilly’s patent claimed the use of tadalafil and its physiologically acceptable salts in the treatment of erectile dysfunction. The interpretation of the term “physiologically acceptable” was key to the defendants’ allegations that the claims were invalid for overbreadth and insufficiency because the evidence at trial showed that any salts of tadalafil that could be made as of the filing date of the patent were unstable and would quickly degrade.
The trial judge held that, based on the patent’s disclosure and the expert evidence, a skilled person would have understood that “physiologically acceptable” means that the salt is not only non-toxic, but also “stable and pure, not degraded”. Having construed the claim term in this manner, the trial judge concluded that the claims were overbroad (the inventors did not have invented such salts) and the patent’s specification was insufficient because it did not enable the skilled person to make “physiologically acceptable” salts of tadalafil.
On appeal, Lilly argued that the trial judge made an error of law in construing the term “physiologically acceptable” in the manner she did. Importantly, Lilly did not argue that the trial judge erred in her assessment of the expert evidence relating to the construction of this claim term, presumably because to do so would engage the high “palpable and overriding” standard of review instead of the lower “correctness” standard for errors of law. As a result, because the trial judge had based her claim construction on the expert evidence, specifically on the opinions of the defendants’ expert, Locke JA. stated that her conclusions in that regard are entitled to deference.
Locke JA. then addressed the issue of whether it was open to the trial judge to have considered and accepted the defendants’ expert testimony. He held that the expert’s opinion on the construction of “physiologically acceptable” was tethered to the patent’s disclosure even though there was no specific reference to stability, purity and non-degradation in the patent. This is because the claims are to be construed from the perspective of the skilled person while taking into account the common general knowledge of that person at the relevant time. In this case, Locke JA. found that it was open to the trial judge to conclude that the skilled person would have understood from the patent as a whole that the claimed salts must not only be non-toxic, but they must also be “stable and pure, not degraded”.
Comments About Insufficiency
Having found that the trial judge did not err in her constriction of the term “physiologically acceptable”, Locke JA. affirmed her holding that the claims were invalid for insufficiency. He did, however, add a comment about the trial judge’s articulation of the legal standard for finding a patent insufficient – that the skilled person would require completion of a “minor research project” to put the claimed invention into practice. Locke JA. noted this phrase appears to come from the Supreme Court’s decision in Teva v Pfizer, which dealt with a patent that failed to identify which of two compounds was favoured by the inventors. That was a different situation than that of Lilly’s patent, which dealt with a more general insufficiency of information in the patent specification. With such a patent, Locke JA held that the specification may be sufficient even if the skilled person must engage in some non-inventive trial and error experimentation, so long as it is not undue. In other words, the patent may be sufficient even if a “minor research project” is required to put the invention into practice, so long as no inventiveness or undue experimentation is involved in doing so.
Lilly has 60 days from the date of the appeal decision to file an application for leave to appeal to the Supreme Court of Canada.