The Actavis v Eli Lilly decision of the UK Supreme Court has been described by some commentators as being a minor gloss on the law of patent infringement and claim scope. This is, however, to underestimate its implications. The Supreme Court has left open the question of whether claim scope is the same for validity purposes as for infringement and has ensured that UK law now includes a doctrine of equivalents which is unfettered by a parallel doctrine of file history estoppel.

Lord Neuberger fundamentally disagreed with and set aside Lord Hoffmann's 2004 ruling in Kirin Amgen v TKT1 that claim scope was to be decided purely as a matter of construction. In a far-reaching decision, Lord Neuberger has held that patent claim scope is rather a two-part test, only the first of which is claim construction with the second being a new doctrine of equivalents.

The 2004 House of Lords decision in Kirin-Amgen was a pivotal one. Lord Hoffmann held that claim scope should be assessed solely on the basis of a purposive construction. The so-called Protocol Questions, which had been devised as an aid to deciding claim scope, were stated to be useful in many cases but not a substitute for trying to understand what the person skilled in the art would have understood the patentee to mean by the language of the claims. This, he said, was the only compulsory question which was set by Article 69 and its Protocol on Interpretation.

Although in the aftermath of the Kirin-Amgen decision, practitioners did initially complain about being, as Lord Hoffmann predicted they might, "cast adrift on a sea of interpretative uncertainty" the sea did calm down over time. It became clear that ascertaining what a skilled person would understand from the language of the claim was something that could be divined from discussions with suitably qualified technical experts in the art. Consequently, it became possible for practitioners to advise on claim scope, patent infringement and freedom to operate and be on relatively firm ground when so doing. It is safe to say that UK practitioners had become comfortable with applying Kirin-Amgen. Significantly, patent courts in other jurisdictions had also commented favourably upon the test with some even adopting the Protocol questions in their own jurisprudence.

Lord Neuberger's new two-part test for assessing whether an alleged infringing article is within the claim scope involves fully opening the door to equivalents which fell outside the traditional purposive construction of the claim. Lord Neuberger is therefore indicating a radical departure from Lord Hoffmann's earlier decision. The claim scope would extend to obviously immaterial variants which would previously, under the law according to Kirin-Amgen, have fallen outside the claim scope. The sea of interpretative uncertainty has whipped up a storm once again.

Right to depart from Kirin-Amgen Decision?

In the Actavis decision Lord Neuberger states "In the absence of good reason to the contrary, it would be wrong to depart from what was said by the House of Lords [in Kirin-Amgen]"2. The context of this comment is within a discussion of the reliance which could be placed on the contents of the patent office file. But the irony is that Lord Neuberger's comment might have been applied more generally in the Actavis case.

Under the common law rules of precedent, the Supreme Court's previous decisions are normally binding on itself and may only be departed from "where it appears right to do so"3,. This has generally been interpreted to cover only those cases where the previous decision is wrong or where it has caused injustice or uncertainty or where it has hindered the development of the law. In light of this, the Supreme Court has generally been quite reluctant to depart from its own previous decisions. In a 1982 case4 it was held that, before departing from its own decision, the House of Lords should be sure that continued adherence to precedent involved the risk of injustice and departure should facilitate the safe and appropriate way of remedying that injustice. In a 2016 decision5 it was stated that "at a time when the cost of litigating can be very substantial, certainty and consistency are very precious commodities in the law". The Supreme Court held that it was well established that the Court should not refuse to follow an earlier decision merely because they would have decided it differently but there had, in the instant case, been a material change in the relevant legal landscape since the earlier decisions which now gave rise to an overwhelming case for changing the law.

If the Kirin-Amgen case had produced injustices or hindered the development of the law in the 13 years since its handing down, one might have expected there to have been a vocal lobby calling for its overturn. It is unfortunate that the Supreme Court saw fit to depart from such a long-standing tenet of patent law as purposive construction without a detailed analysis of the rationale for such departure.

Return of the Angora Cat?

One of the other key tenets of UK patent law is "that the construction of a claim is the same whether validity or infringement is to be considered; no patentee is entitled to the luxury of an “elastic” claim which has a narrow meaning in the former case but a wide meaning in the latter6.

In the Supreme Court it is fair to say that the impact upon the validity of the patent claim of an extremely generous scope which encompassed equivalents, received minimal examination. The court appears to have proceeded on the basis of a fallacy; that a patentee always wants the broadest scope of protection possible. However, in the process of claim formulation and refinement, during the dialogue with the patent office, the patentee actually has a number of competing considerations in mind. These include formulating the claim so that it is new and inventive, (i.e., avoids the prior art), ensuring that it is sufficient, (i.e., properly enabled), ensuring that the patent gives practical protection against likely infringements and perhaps most importantly, formulating the claim so that it is formally acceptable to the examining authority.

These various factors are ever-present in the minds of patentees, patent attorneys, litigators and others steeped in the vagaries of patent law. Practical considerations inevitably come into play: a patentee may know that a certain form of claim would be immediately acceptable to the office and so be granted quickly, while another, broader form might be granted but only more slowly and after some resistance. If there is a practical need to begin infringement proceedings, patentees often opt for the narrower claim in such circumstances. It is not the case that at the time of drafting the claims the patentee necessarily wants them to have the broadest possible scope. A broad scope may embrace the prior art, or be insufficiently supported by the disclosure, and so invalidate the patent.

The upshot is that when a court comes to construe a patent's claims, it is perfectly possible that the reasons for including a limitation to the claims are not apparent from the specification. But that does not mean that there was no reason, or that the limitation is not important.

Doctrine of Equivalents unchained

In the USA, the rule of file history estoppel acts as a check upon the doctrine of equivalents. Where a patentee has made voluntary statements and claim amendments during prosecution which limited the literal scope of the claim, then the patentee is estopped from later reneging on this and seeking to re-assert the abandoned claim territory through an argument based on equivalents. A similar situation exists in the Netherlands. In Actavis, however the Supreme Court has made it clear that the file history may be consulted only in very limited circumstances and therefore does not run in parallel with the revised Protocol questions.

It is submitted that this new UK approach sees the pendulum swing too far in favour of patentees and denies third parties any reasonable degree of certainty. For a patentee to be free to narrow a claim to secure grant and subsequently re-expand the claim scope into the same territory to catch infringers is precisely the "elastic claim" situation mentioned earlier, which the English courts have been determined to avoid. The Eli Lilly file history should have been the exemplar case of a patentee irretrievably abandoning claim territory. That it was held otherwise, makes the practitioner's task of advising on claim scope in other cases that much more difficult.

'Wriggle room' for Judges, if not Lawyers

Although the Actavis decision reflects a sea-change in the law of patent claim scope and infringement, there is a school of thought that says the practical implications could be rather less marked. Now that the Supreme Court has handed down its decision, it is for the lower courts to implement the law change on a day-to-day basis. There are several aspects of the Actavis decision which may lend themselves to an enhanced degree of flexibility for a lower court judge to come to a desired result. The first such aspect is the inventive concept. Rather than focusing solely on the language of the claim, Lord Neuberger stated: "The [first Protocol] question as framed by Hoffmann J, with its emphasis on how 'the invention' works, should correctly involve the court focusing on 'the problem underlying the invention', 'the inventive core', or 'the inventive concept' as it has been variously termed in other jurisdictions."

Inventive concept of a patent is an issue that pervades a number of aspects of UK patent law including the Pozzoli test for obviousness. The Supreme Court in Actavis has deliberately left the concept unformulated. As such, it will be for lower courts to identify inventive concepts of patents in suit on a case by case basis. Indeed, many of the UK patent cases decided up to 2017 on the basis of the Improver/Protocol questions had similar tasks to identify "the invention" and "the way the invention works" and this was with the more straightforward underlying approach of purposively construing the claim in context. Deciding upon the right level of generality to adopt in order to identify the "invention" was a layer of flexibility on top. Post-Actavis, the exercise will be to identify the "inventive core or inventive concept" but in addition to do so with the appropriate level of generality. This involves a significant amount of inherent "wriggle room" for the lower courts.

Another potential area of tractability for the lower courts revolves around step one of Lord Neuberger's two-part test, whereby it is necessary to construe the claim according to the normal principles of interpreting commercial documents. The principles of normal interpretation were said to have been affirmed in the Supreme Court case of Wood v Capita Insurance7, which related to interpretation of contracts. The lawyer/judge must use and balance the tools of textualism and contextualism in order to ascertain the objective meaning of the language which the parties have chosen. The balance to be adopted between the textual approach and the contextual approach is surely fertile ground for judicial flexibility.

When answering Protocol question 3, the form of the question has changed and this arguably introduces a further degree of flexibility for the lower courts. Question 3 now asks whether the reader of the patent would have concluded that the patentee nonetheless intended strict compliance with the literal/normal meaning of the relevant claim to be an essential requirement. Previously, under Lord/Mr Justice Hoffmann's formulation, question 3 asked whether the reader of the patent would have concluded all of this this but from the language of the claim. Clearly, post Actavis, the language of the claim is no longer a necessary part of this assessment. This appears to be opening the door to introducing the underlying factual matrix, something which as shown above is already part of normal interpretation under Wood v Capita. It is submitted that this gives plenty of scope to lower court judges to find any number of "plausible reasons" why a given patentee should in fact have wanted to limit themselves to the strict language/normal meaning of the claim.

Such flexibility which appears to be available to the lower court judges, may make their lives easier when deciding cases but surely makes practitioners' lives more difficult in preparing and advising on them.

This article was first published in European Intellectual Property Review, EIPR (2018) Vol 40 (1) pp1-3