In a recent decision the UK Supreme Court reviewed the scope of protection that should be granted to protect patentable inventions. This new approach is likely to result in broader protection for patentees and greater commercial uncertainty for those who are trying to determine whether they have freedom to operate.
Doctrine of Equivalents
Many jurisdictions around the world have the concept of a "doctrine of equivalents". This is a legal rule that allows a court to hold a party liable for patent infringement notwithstanding that their product or process does not fall, literally, within the claims of the patent.
The rational for a doctrine of equivalents is driven by the desire to offer an inventor adequate protection in return for this public disclosure of his or her invention: it cannot be fair to allow someone to take the benefit of an invention yet avoid infringement of the patent based on technicalities around the precise wording of the patent's claims.
However, until the recent Supreme Court decision in Actavis v Eli Lilly  UKSC 48 there was – in fact – no doctrine of equivalents in the UK.
An Historical Understanding of UK Claim Construction
Article 69 of the European Patent Convention ("EPC") explains the extent of protection provided by a patent. It states that:
"The extent of the protection conferred by a European patent or a European patent application shall be determined by the claims. Nevertheless, the description and drawings shall be used to interpret the claims."
Further guidance is provided in the Protocol to Article 69 of the EPC. In essence, Article 1 of the Protocol requires a middle way to be found between two extreme approaches:
1. A literalist approach, where the claims are restricted to their literal meaning; and
2. A liberal approach, where the claims serve only as a guideline.
When the EPC was amended in 2000, Article 2 of the Protocol was introduced. It states explicitly that:
"For the purpose of determining the extent of protection conferred by a European patent, due account shall be taken of any element which is equivalent to an element specified in the claims".
Until recently, the UK position determining the scope of a patent claim for the purpose of assessing patent infringement has been defined by three landmark decisions: Catnic  RPC 183, Improver  FSR 181 and Kirin-Amgen  RPC 9. Together with the Protocol to Article 69, these decisions have resulted in the courts adopting a "purposive construction" to the language of a patent's claim to resolve the issue of infringement.
In essence, "purposive construction" meant considering the patent's claims and giving them the meaning that the person skilled in the art would have understood the patentee to be claiming in light of the content of the specification. All questions of infringement could be answered by reference to the overarching principle of purposive construction.
Historically therefore, the law on the extent of protection of a patent (i.e. how far the monopoly stretched) was considered as being synonymous with the correct interpretation of the claim language. Infringement by equivalents was considered only in the context of construing the patent's claim through the prism of "purposive construction". In Improver, Hoffmann J set out three questions to consider when deciding whether an equivalent fell within a purposive construction of the patent's claims:
1. Does the variant (i.e. an embodiment that does not comply with the literal meaning of a claim) have a material effect upon the way the invention works? If no;
2. Would this (i.e. that the variant had no material effect) have been obvious at the date of the publication of the patent to a reader skilled in the art? If yes;
3. Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention?
In Kirin Amgen Lord Hoffman went on to explain that the Improver questions were only guidelines, more useful in some cases than others, but that the principle of purposive construction was the "bedrock" of patent construction which was universally applicable. In essence, the question to be asked was: what would the skilled person have understood the patentee to have used the language of the claim to mean?
Actavis v Eli Lilly  – a fundamental change
In Actavis the UK Supreme Court has developed a fundamentally different approach to assessing the scope of a patent's claims
Lord Neuberger divided the question for infringement into two separate issues. When considering infringement from now on, the court should therefore ask:
(1) Does the variant infringe any of the claims as a matter of "normal interpretation"? If not;
(2) Does the variant nonetheless infringe because it varies from the invention in a way which is immaterial?
Previously, in Kirin-Amgen these two issues were conflated into a single issue (purposive construction). The new approach set out in Actavis therefore seeks to more clearly follow the distinction between Article 1 and 2 of the Protocol and, in the second question, formally introduces a doctrine of equivalents into UK law.
How closely aligned the "normal interpretation" is to "purposive construction" is unclear. Further guidance will need to be provided by the Courts on this issue, although recent first instance decisions following Actavis have stated that this remains a test of purposive, rather than literal, construction.
In considering how to answer the second question the court reformulated the Improver questions in a manner which significantly increases the prospects of an equivalent infringing.
In relation to the first Improver question, the Supreme Court emphasised the identification of the inventive concept as key when considering whether the variant achieved the same result in the same way as the invention.
The biggest changes were in relation to the second Improver question. Here Lord Neuberger indicated that this question should be asked on the basis that the skilled person already knows that the variant works to the extent it actually does work, leaving the skilled person only to answer whether it was obvious that it achieved substantially the same result in substantially the same way as the invention. This lowers the burden on the patentee by removing the requirement that it was obvious to the skilled person at the priority date that the variant would work. Variants that are based on developments which have occurred since the priority date therefore fall within the scope of the UK doctrine of equivalents even if they were not foreseeable at the priority date.
Finally, although the third Improver question was not altered, guidance was given on its correct application.
File Wrapper Estoppel
Not only did Actavis introduce infringement by equivalents into UK law, but it also marked a change in the position around the examination of the prosecution history when interpreting the meaning of a claim.
Historically the UK courts have not considered the prosecution history to be of relevance to interpretation of a patent. However, Lord Neuberger introduced some room for manoeuvre on this issue in Actavis. He considered the prosecution history could be of use in two limited scenarios:
1. Where the point at issue is truly unclear if one confines oneself to the specification and claims of the patent, and the contents of the file unambiguously resolve the point: or
2. Where it would be contrary to the public interest for the contents of the file to be ignored (something that would be exemplified where the patentee had made clear to the EPO that he was not seeking to contend that his patent would extend its scope to the sort of variant which he now claims infringes).
In a recent first instance decision applying Actavis, Carr J held that reference to the prosecution history would be the exception and not the rule.
Impact of the decision
The impact of this decision will play out in the UK courts for years to come. The decision has introduced a significant new line of attack for patentees and companies that previously chose not to commence infringement proceedings may now be tempted to do so. Equally, companies that have previously considered themselves to have "worked around" patents would be well advised to re-visit their freedom to operate opinions.
Interestingly much of Lord Neuberger's judgment focussed on an analysis of other European countries' laws and an apparently significant consideration was to align UK law with that in other European jurisdictions. The continued harmonisation of European patent law will hopefully result in more consistent decisions when applying different national laws. That may further increase the current trend for the infringement of foreign patents to be decided in the UK courts by way of declaratory judgment.