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UK Supreme Court grasps nettle of doctrine of equivalents

By Hugh Dunlop

Eli Lilly v Actavis UK Ltd [2017] UKSC 48 (12 July 2017). 

The UK Supreme Court has overturned 35 years of English patent law by applying a doctrine of equivalents to find that Actavis’s products directly infringe Eli Lilly’s patent.

The Court has reformulated the “Improver” questions originally posed by Lord Hoffmann in Improver Corp v Remington Consumer Products Ltd [1990] FSR 181 (subsequently known as the “Protocol” questions).  In doing so, the Supreme Court dealt with some important issues related to patent infringement, including the correct approach to the interpretation of patent claims (particularly in the light of the requirement under the EPC 2000 to take alleged equivalents into account) and also the extent to which it is permissible to make use of the prosecution history of a patent when determining its scope. 

The interesting point about this decision is that a variant can now infringe when “it varies from the invention (as claimed) in a way or ways which is or are immaterial”, which may leave patent lawyers feeling cast further adrift on a sea of interpretive uncertainty.

Background to Lilly v Actavis

Eli Lilly and Company (“Lilly”) have marketed pemetrexed disodium as a cancer treatment under the brand name Alimta since 2004, and own European Patent No. 1 313 508 (“the Patent”) for the use of pemetrexed disodium in the manufacture of a medicament for use in combination with vitamin B12 (and, optionally, folic acid) for the treatment of cancer, due to expire in June 2021.   

Pemetrexed, a member of a class of chemicals known as antifolates, contains two -CO2H units and, therefore, is an acid (hence it is also known as pemetrexed diacid):

Although known to have therapeutic effects on cancerous tumors, pemetrexed can often have seriously damaging (sometimes, even fatal) side-effects when used on its own. The essential disclosure of the Patent was that the damaging side-effects could largely be avoided if a compound called pemetrexed disodium was administered together with vitamin B12.  Pemetrexed disodium is known as a salt: it has two -CO2Na units instead of two -CO2H units and, when dissolved in water, the two sodiums separate from the rest of the molecule as positively charged cations, and the rest of the molecule becomes a negatively charged pemetrexed anion. 

Actavis intended to market a generic pemetrexed product for the treatment of cancer, and sought declarations of non-infringement on the basis that the active ingredient in their generic product was pemetrexed diacid, pemetrexed dipotassium or pemetrexed ditromethamine and not pemetrexed disodium as claimed.

  In 2014, Mr Justice Arnold held that Actavis’s products did not infringe the UK, French, Italian or Spanish designations of the Patent, either directly or indirectly (see Actavis UK Ltd v Eli Lilly & Company [2014] EWHC 1511 (Pat)).  That decision was partially upheld on appeal by the Court of Appeal, which took the view that there would be indirect infringement, but not direct infringement (see Actavis UK Ltd v Eli Lilly & Company [2015] EWCA Civ 555).  The court agreed with the judge’s conclusion that the proper construction of the claim did not extend to pemetrexed diacid or any other pemetrexed salts other than disodium because the skilled reader of the patent would not have expected any of Actavis’s pemetrexed salts to convert into pemetrexed solution when dissolved in an aqueous solution (Improver v Remington considered) and, on that basis, there could be no direct infringement by Actavis’s dealing in the active ingredients of the generic product. 

A solution made by dissolving pemetrexed dipotassium in plain water would not infringe because such a solution would contain only potassium ions and pemetrexed ions.  However, Actavis’s intended implementation was to dissolve and/or dilute each of the active ingredients in saline solution and, therefore, sodium ions would be present.  The judge had dealt with this issue by accepting Actavis’s submission that “at no point is pemetrexed disodium used in the manufacture of a medicament by anyone”.  However, as the Court of Appeal explained, the skilled team would have understood from the Patent that pemetrexed disodium was used to refer not only to the solid, but also to solutions containing sodium ions and pemetrexed ions with at least a 2:1 ratio.  Further, the language of s 60(2) of the Patents Act 1977 did not require the supply of an element of the claim, but a means relating to an essential element.  Consequently, the invention was put into effect when a pharmacist reconstituted or diluted the Actavis products in saline, because there was a stage in the course of that activity when pemetrexed disodium was present and used, which would amount to indirect infringement.  Accordingly, the court disagreed with the judge on the issue of contributory infringement.  It was common ground that there was no detectable difference in the laws of France, Italy and Spain on the approach to contributory infringement so it followed that the declarations of non-infringement should also be refused in those countries.  

Lilly appealed to the Supreme Court on the issue of direct infringement, and Actavis cross-appealed against the rejection of their case that there would be no indirect infringement.


The Supreme Court unanimously allowed Lilly’s appeal and dismissed Actavis’s cross-appeal.  Giving the lead judgment, Lord Neuberger said that as a matter of ordinary language, it was quite clear that the only type of pemetrexed compound to which the Patent’s claims expressly extended was pemetrexed disodium.  In those circumstances, the Protocol on the Interpretation of Article 69 of the European Patent Convention (“the Protocol”) was crucial to Lilly’s contention that the scope of protection afforded by the Patent extended to the Actavis products.

Lord Neuberger noted that “the drafting of the Protocol bears all the hallmarks of the product of a compromise agreement” which he said was unsurprising, given the “inevitable conflict between the desirability of giving an inventor an appropriate degree of protection in a particular case and the need for clarity of principle as to the extent of such protection generally”.  There was also “an unavoidable tension between the appropriateness of giving an inventor a monopoly and the public interest in maximising competition”.

More specifically, it was clear from Article 1 of the Protocol that the scope of protection afforded to a patentee was not to be limited by the literal meaning of the claims.  However, it was not at all clear how far a court was permitted to move away from the literal meaning.  Secondly, it was apparent from Article 2 of the Protocol that there was potentially a difference between interpreting a claim and the extent of the protection afforded by a claim, and, when considering the extent of such protection, equivalents had to be taken into account, but no guidance was given as to precisely what constituted an “equivalent” or how equivalents were to be taken into account.  As Lord Neuberger explained, three significant UK cases had considered the question of how far one could go outside the wording of a claim so as to enable the patentee to enjoy protection against products or processes which were not within the ambit of the actual language, construed in accordance with ordinary principles of interpretation.


This judgment says it is time to “grasp the nettle” of not merely identifying what the words of a claim would mean in their context to the notional addressee, but also considering the extent if any to which the scope of protection afforded by the claim should extend beyond that meaning.

As discussed in the present case, recent UK case law had moved away from any doctrine of equivalents or similar interpretive tool; Lord Hoffmann in Kirin-Amgen was openly sceptical of the doctrine of equivalents in the US and the pith and marrow doctrine in the UK, remarking that both “were born of despair” and that “American patent litigants pay dearly for results which are no more just or predictable than could be achieved by simply reading the claims”.  After Catnic, the UK courts adopted a principle of construction, which actually gave effect to what the person skilled in the art would have understood the patentee to be claiming.  However, with the advent of Article 2 of the Protocol, came the need to take “due account” of any element which was equivalent to an element specified in the claims and the key limitation of the purposive construction theory is that it cannot protect an equivalent or variant that lies beyond the language of the claims.  Another drawback of purposive claim construction is that unforeseeable technology arising after the patent is drafted might not be encompassed by the claim, depending on the generality of the language of the claim.  Under purposive construction, an unforeseeable (or foreseeable) equivalent that cannot be found within the meaning of the language of the claim cannot infringe, which arguably places too much expectation on drafters of patent claims in the absence of significantly more guidance on patent scope.  As Lord Neuberger noted in the present case, it is worth mentioning that Lord Diplock himself in Beecham Group Ltd v Bristol Laboratories Ltd [1978] RPC 153, 200 rejected a submission that “[t]he increasing particularity with which claims are drafted … has made the doctrine [of pith and marrow] obsolete”, but said that the doctrine “still remains a part of patent law”.

This decision is likely to make advising on patent infringement more difficult: practitioners will have to dust off earlier opinions and see if they need to be revised, and there may be a flurry of suits where companies thought they were safe and now find they may infringe.

For questions about this matter or related issues, please contact our Partner Hugh Dunlop (

Monday, July 31, 2017