In the 15 months that have passed since the Supreme Court introduced a Doctrine of Equivalents in the Actavis v Lilly pemetrexed decision which we reported on – see here for a re-cap, no reported case has turned on this new doctrine. However, in an interesting case handed down by the Court of Appeal this month, Lord Kitchin (now in the Supreme Court) has provided some guidance both on the application of the Doctrine of Equivalents in a case where there was held to be no infringement as a matter of normal interpretation and also on prosecution history estoppel (known in the US as “file wrapper estoppel”). On this latter point, the judgment provides a further indication that prosecution history is rarely likely to be taken into account by the Court when considering claim scope.
On the 10th October 2018, the Court of Appeal handed down the decision of Icescape Ltd v Ice-World International BV & Others  EWCA Civ 2219. The appellants (collectively, ‘Ice-World’) appealed against the decision of John Baldwin QC, sitting as a deputy High Court judge. The appeal was brought on the grounds that (i) their UK patent for a cooling system for a mobile ice rink was invalid; (ii) had it been valid, it would not have been infringed by the respondent; (iii) they were unable to rely on the defence to groundless threats under the Patents Act 1977 Pt I s.70(2). The High Court decision was upheld and the appeal dismissed.
Background to the case
Ice-World made a system for cooling mobile ice rinks and leased them to third parties. Ice-World owned the patent in question, EP (UK) 1,462,755 entitled ‘Cooling member for a mobile ice rink’. The respondent (‘Icescape’) operated mobile ice rinks made and leased to it by Ice-World. The business relationship came to a frosty end and so Icescape designed, made and began to operate its own mobile ice rink.
Ice-World wrote to Icescape asserting that its mobile ice rink infringed Ice-World’s patent. A year later, Ice-World wrote to a large number of the respondent’s actual and potential customers asserting the infringement. In June 2016, the respondent issued proceedings seeking damages for groundless threats of patent infringement, a declaration of non-infringement and an order that the patent be revoked. The parties agreed that the patent would be invalid as a result of Ice-World’s own prior use unless Ice-World could rely on a priority document to maintain the patent’s earliest priority date.
The appellants counterclaimed, asserting that the patent was valid and infringed by the respondent. Ice-World accepted that they had written threatening letters but maintained that those threats were justified. They also contended that if the patent was invalid, they had a defence to the claim for threats under s.70(2) because they had not known and had no reason to suspect that the patent was invalid.
Validity of the patent
Following MedImmune Ltd v Novartis Pharmaceuticals and HTC Corp v Gemalto SA, for a patent to claim priority from an earlier patent filing, the priority document must disclose the information forming the subject of the patent “directly and unambiguously” as a whole when read by the skilled person equipped with the “common general knowledge”. At first instance, it was found that Ice-World could not rely on the priority document because there was no express or implicit disclosure of the key novel and inventive features in the priority document.
The Court of Appeal determined that the judge had rightly concluded that the patent was not entitled to the claimed priority, was therefore invalid and had to be revoked (at -).
Following Catnic, Kitchin LJ expressed how the courts had adopted a purposive approach to the interpretation of patents rather than a purely literal one whereby “strict compliance with a particular verb or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect upon the way the invention worked.”, at .
The position remained settled until Actavis v Lilly adopted a markedly different approach. Following Actavis, the problem of infringement is best addressed by two issues, considered through the eyes of the “notional addressee” (i.e. the anticipated audience for the patent):
(i) does the variant infringe any of the claims as a matter of normal interpretation; and, if not,
(ii) does the variant nonetheless infringe because it varies from the invention in a way or ways which is or are immaterial, at .
Kitchin LJ explained the approach taken by Lord Neuberger at  to state that (ii) was to be determined by three questions:
a) notwithstanding that it was not within the literal, or normal, meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention;
b) would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it did so in substantially the same way as the invention;
c) would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention.
In order to show infringement within limb (ii), a patentee would have to establish that the answer to questions (a) and (b) was “yes” and that the answer to question (c) was “no”.
As to question (a), Icescape’s system had a parallel rather than a series connection between the manifolds which was said to possibly confer advantages but was determined to have nothing to do with the inventive core of the patent. The concept of equivalent features applied here is quite broad and it is not a simple drop-in replacement of one component for another but instead taken as a wholesale configuration. Therefore, the answer to (a) was yes.
The same logic applied for question (b): because the variant did not affect the inventive core, it would be obvious to the skilled person that Icescape’s system achieves substantially the same result as the invention and does so in substantially the same way. Therefore, the answer to (b) was also yes.
On question (c), the fact that the language of the claim did not cover the variant was not enough to find that Ice-World intended strict compliance with the literal meaning of the claim. Further, Kitchin LJ reasoned that, as the variants were outside the inventive core, these variants were not an essential requirement of the invention. Therefore, the answer to question (c) was no, (at  – ).
Floyd LJ, agreeing with Kitchin LJ’s judgment, added that there was nothing to suggest that the patentee regarded a series connection as essential in any relevant sense, (at -). In practice this means that, to assess the scope of the claims for infringement, it is necessary to identify the ‘inventive core’ of the patent. This is non-trivial for third parties.
Floyd LJ highlighted that this judgment unfortunately does not resolve the issue of the approach the courts should take to the scope of protection when considering validity as opposed to infringement nor the approach to inventive variants (at ). The Court of Appeal found, contrary to the judge, that the patent would have been infringed, if valid.
Prosecution history estoppel
In line with Actavis, the prosecution history was permitted to be considered in the case, (at - and  – ).
The patent attorneys acting for Ice-World responded to an objection of the Examining Division by deleting one claim the EPO said lacked novelty and providing a new claim comprising additional integers. Icescape attempted to argue that certain features of the granted claim could then not be asserted as inessential parts of the invention. Kitchin LJ found no merit in Icescape’s argument as it was impossible to determine if the objection raised at the EPO was sound and it was impossible to discern from the correspondence that Ice-World were surrendering any ability to argue the features were inessential or accepting a limitation of the scope of the claims. The correspondence fell well below the threshold set in Actavis and Kitchin LJ said this was a good illustration of why it is generally so unprofitable to explore the prosecution history. The key takeaway from this is that the courts do not appear to consider the prosecution file to be a good indicator of the inventive core and Icescape should have just let it go. Therefore, patentees can be less concerned that amendments made during prosecution of the patent will limit the scope of the monopoly.
Ice-World conceded that the letters to Icescape’s customers constituted threats but appealed the judge’s finding of a lack of defence under s.70 of the 1977 Act. Although this defence has since been amended by the Intellectual Property (Unjustified Threats) Act 2017, the former provisions continued to apply to the threats in issue.
Ice-World coolly argued it had no reason to suspect the patent was invalid as its patent attorney had not raised the possibility that the priority claim might be defective and because it had relied upon an earlier letter of advice from Venner Shipley LLP on the validity of the patent. It was not until a letter was received from Icescape’s solicitors that it was alerted to the potential priority issue.
The Court of Appeal agreed with the judge that in the circumstances, the appellant would have great difficulty establishing it had no reason to suspect the patent was invalid because Ice-World made prior public use of the invention. The position was considered worse still since the judge had been provided with no information about the knowledge or understanding of the directing minds of Ice-World and no explanation for the lack of evidence. The judge had been entitled and right to have found that the appellant had failed to make good the s.70 defence, at  and -.
- When faced with an alleged claim of patent infringement to fully assess the scope of the claims it is necessary for parties to identify the ‘inventive core’ of the patent.
- Involving professional help, from specialist patent litigation lawyers and patent attorneys early can be vital to raising a successful defence.
- In patent infringement cases the prosecution history is rarely likely to be taken into account by the Court when considering claim scope.
- The law on groundless threats is complex and has been amended since this case. It is therefore prudent to seek early legal advice when asserting intellectual property rights.
 Actavis UK Ltd v Eli Lilly & Co  UKSC 48,  1 All E.R. 171
 Icescape Ltd v Ice-World International BV and others  EWHC 42 (Pat), 23 January 2017
 MedImmune Ltd v Novartis Pharmaceuticals UK Ltd  EWCA Civ 1234,  R.P.C. 27
 HTC Corp v Gemalto SA  EWCA Civ 1335,  Info. T.L.R. 337
 Catnic Components Ltd v Hill & Smith Ltd  F.S.R. 60
 Actavis UK Ltd v Eli Lilly & Co  UKSC 48,  1 All E.R. 171