At a recent pre-trial review in the Facebook v Voxer litigation, Birss LJ considered whether it was necessary expressly to plead reliance upon the doctrine of equivalents. After considering the various factors, he found that it was necessary.

Also of interest was the guidance (albeit not forming part of the ratio of the judgment) on the extent of the required pleading. In the view of Birss LJ, the minimum requirement was to contain a statement, by reference to each relevant claim feature (and claim) that equivalence is relied on. Further particularisation, for example of the patentee's case on inventive concept and other aspects of the Actavis test, could then come later at the time when claim charts or a statement of case on infringement is produced.

This guidance on what was, to date, an unclear requirement will be welcomed by many in the patent litigation sphere.