Patentees who intend to rely on the doctrine of equivalents must now say so in the Particulars of Infringement. As a minimum, this requires a patentee to state the claims and claim features in relation to which equivalence is relied upon.

Formally made part of UK patent law in 2017 following the Supreme Court decision in Actavis v Lilly, the doctrine of equivalents extends the scope of protection of patent claims beyond their normal (or purposive) interpretation to include immaterial variants.

Patent pleadings in High Court cases are relatively terse and don't go into great detail about a party's case. However, since Actavis, litigants have been unclear about whether reliance on the doctrine of equivalents must be pleaded and, if so, at what stage. As a result, it has been common for an alleged infringer to ask whether the patentee intends to rely on infringement by equivalence in advance of exchanging expert evidence (as an expert will often need to address the "Actavis questions" in their reports).

Background and decision

Following a pre-trial review in a patent action between Facebook and Voxer IP concerning an alleged infringement by certain features of Facebook Live and Instagram Live, Lord Justice Birss (siting as a Patents Court judge) has provided guidance about the way reliance on the doctrine of equivalents should be pleaded in patent cases.

Birss LJ is well known for encouraging litigants to more fully explain their cases at an earlier stage. In his judgment, he decided that reliance on the doctrine of equivalents should be formally set out at an early stage in proceedings (in the Particulars of Infringement). A patentee must, as a minimum, explain the claims and claim features in relation to which equivalence is relied upon. He did not think this would represent a serious burden on a patentee (likening the burden to that faced by a party challenging a patent's validity).

However, he did not decide whether the inventive concept (for equivalence purposes) needed to be characterised in the Particulars of Infringement or whether all details necessary to support the case on equivalence needed to be pleaded fully from the outset. He indicated that neither was probably necessary and that the appropriate place to plead out these matters would be later, in a Statement of Case on Infringement.

OC comment

This decision makes it clear that a patentee must fully consider its infringement position from a much earlier stage in proceedings, with equivalence issues now being front-loaded. It is no longer good enough for a patentee to be reactive to questions about its infringement case from the counter-party.

A patentee must give consideration to whether it wishes to rely upon the doctrine of equivalents at the outset of any infringement claim or before making a counterclaim (and if so, in relation to which claims and claim features). Moreover, it should also consider early on how the patent's inventive concept should be characterised and the facts and matters it will need to prove to establish its equivalents case (the first and second Actavis questions), including with appropriate experts.

The trial between Facebook and Voxer IP began on 12 April 2021 and will be closely watched.

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