Warner-Lambert v Actavis: a summary from the UK Supreme Court hearing

Infringement and plausibility were the biggest issues on the battleground in the UK Supreme Court’s hearing in a case dealing with second medical use patents, as Claire Phipps-Jones, Katie Cambrook and Rachel Mumby of Bristows report.

From February 12 to 15, 2018, the UK Supreme Court (comprising Lords Mance, Sumption, Hodge, Reed and Briggs) heard the latest instalment in Warner-Lambert v Actavis/Mylan. The case concerns the validity and infringement of Warner Lambert’s (Pfizer’s) second medical use patent with Swiss-type claims covering pregabalin for the treatment of pain.

In an earlier case, the Court of Appeal found that Pfizer’s patent was invalid, as the data in the patent was not sufficient to render a claim covering neuropathic pain plausible (it would have been understood that pregabalin would only have been suitable to treat peripheral, not central, neuropathic pain). Following this finding, Pfizer sought to narrow the claim to cover only treatment of peripheral neuropathic pain, but was not allowed to do so as the Court of Appeal held that this would be an abuse of process. Finally, the Court of Appeal made some comments on how Swiss-type claims would be infringed. Each of these points was the subject of the appeal to the Supreme Court.

Arguing that the patent was valid, Pfizer suggested that there was no role for plausibility in considering whether the skilled person reading the patent would be able to work the whole of the invention claimed. If the Supreme Court thought that there was a role, Pfizer suggested that there should only be a low threshold that had to be met. Actavis/Mylan argued that a more stringent test should be applied – namely that the skilled person in this field reading the patent with the common general knowledge in mind must have a reasonable prospect of success in establishing that pregabalin would treat neuropathic pain (including central neuropathic pain). Alternatively, they suggested that the patent must show a direct effect on the mechanism of the disease. Actavis’s/Mylan’s tests would both result in the patent being invalid.

On construction (ie, in determining what the language of the patent claim means), Pfizer initially argued that one shouldn’t go looking for difficulties if, on the face of the language in the claim, there is no ambiguity. However, if there is real ambiguity, the “validating principle” that applies to contract construction should be applied, in which the Supreme Court seeks to uphold the claim (as a matter of policy). Actavis/Mylan instead suggested that the Supreme Court should interpret claims using ordinary English, with assistance of technical teaching drawn from the body of the patent.

Pfizer further argued that it should have been allowed to amend its patent following the finding that the claim was invalid. This was for three reasons: first, that a patentee has a right to amend, which arises only once it has been made aware by the Supreme Court that its patent is invalid; second, that it was known following the judgment that a claim to treatment of peripheral pain would be valid and that relief should be granted in respect of the part of the claim that is valid and infringed; and finally, that it was disproportionate not to allow the amendment, as Pfizer could have paid Actavis’s/Mylan’s costs of dealing with the amendment at a future trial on the validity/infringement of the amended claim. Actavis/Mylan countered those three arguments.

Arguably the most interesting battleground, and the area where most options were presented to the Supreme Court, was infringement. Previously, the Court of Appeal (obiter) proposed a test for direct infringement based on the manufacturer’s knowledge or reasonable foreseeability of the ultimate intended use for the patented indication, qualified by a caveat that the element of intention can be negatived where the manufacturer has taken all reasonable steps to prevent infringement.

On indirect infringement, the Court of Appeal had reiterated that means for putting the invention into effect must be provided, but that there is no requirement for a downstream act of manufacture. Pfizer initially argued for a test limited to the foreseeability of downstream use, but in closing fell back on the Court of Appeal’s “reasonable steps” approach. Actavis/Mylan principally argued that there can only be infringement by the manufacturer where the manufacturer subjectively intends the product to be used for the patented indication, although they accepted as an alternative that objective intention may be sufficient, and as an ultimate fall back suggested an approach that simply required consulting the product label.

The Supreme Court confirmed that it will take “some time” to prepare the judgment. Based on the previous patent cases, the decision may be expected in early summer.

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