By Gordon Harris, Paul Inman, Ailsa Carter
The UK Supreme Court has handed down its long-awaited judgment in Warner-Lambert v Generics & Anr  UKSC 56. It took the form of separate judgments from four Law Lords, who agreed that key claims of Warner-Lambert’s patent were invalid and could not be amended, but disagreed about almost everything else.
Deciphering what exactly the Supreme Court has ruled is not straightforward. What we can say is that the concept of plausibility is now not a “low, threshold test” (as the Court of Appeal had indicated); but the Law Lords were split on what the test should be. Consequently the law in this area has become unsettled. Further, the interpretation of Swiss form claim language and the operation of the infringement provisions in respect of such claims has been unsettled by the Supreme Court’s obiter reasoning on these issues, some of which appears to conflict with previous judgments of the court without express departure.