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Posted on 13 July 2017 by David Rose & Nina O'Sullivan

Inside IP: Supreme Court re-writes rules on scope of patent prosecution

In a groundbreaking decision, the Supreme Court has fundamentally revised the UK approach to interpretation of patent claims and, in particular, has confirmed the extent of the role to be played by a doctrine of equivalents. In doing so, the Court has considered and re-formulated the Improver questions on patent construction, and also clarified the limited role the prosecution history of a patent can play when determining its scope.

As a result of its less strict approach to construction compared to the High Court and Court of Appeal, the Supreme Court has overturned those courts' findings on direct infringement, finding that Actavis's generic products would directly infringe Lilly's pemetrexed disodium patent (and would also indirectly infringe). 

The Supreme Court's judgment will have far-reaching ramifications in determining the scope of protection in future infringement cases. 


Lilly's Patent, which is due to expire in 2021, includes claims for the use of pemetrexed disodium in the manufacture of a medicament for use in combination with vitamin B12 - and optionally a folic protein binding agent - for the treatment of cancer. Its earlier patent for pemetrexed expired in December 2010, and the related SPC expired in December 2015. Lilly has marketed pemetrexed disodium as a cancer treatment under the brand Alimta since 2004, with great success.

Actavis wishes to launch a competing generic product involving pemetrexed compounds being used together with vitamin B12: rather than pemetrexed disodium, the active ingredients are either pemetrexed diacid, pemetrexed dipotassium or pemetrexed ditromethamine. It applied for declarations of non-infringement in respect of the UK designation of the Patent, and also the French, Italian, Spanish and German designations.

At trial, Arnold J was prepared to grant the declarations. On direct infringement, in particular, he concluded that the skilled team would understand the reference to pemetrexed disodium to mean that alone, and nothing else. The Court of Appeal agreed with Arnold J's decision on direct infringement, but overturned him on indirect infringement. The Court of Appeal also disagreed with him on the proper role to be played by the prosecution history of the patent, with Floyd LJ's analysis suggesting there was little remaining scope for it in future cases.

Both Lilly and Actavis appealed to the Supreme Court.

Supreme Court decision

Direct infringement

As a matter of ordinary language, the only type of pemetrexed compound to which the claims of the Patent expressly extend is pemetrexed disodium. However, as is made clear by The Protocol on the Interpretation of Article 69 (as amended in 2000) of the European Patent Convention, the scope of protection is not limited to the literal meaning of a claim. The question for the Supreme Court was: how far can you go outside the wording of a claim, and what is the role to be played by a doctrine of equivalents, given Article 2 of the Protocol (introduced by the 2000 amendment) which provides that 'due account shall be taken of any element which is equivalent to an element specified in the claims'?

In determining the proper approach, Lord Neuberger, giving the Supreme Court's decision, reviewed the three leading UK decisions (Catnic, Improver and Kirin-Amgen), as well as cases from Germany, France, Italy, Spain and the Netherlands. He concluded that the proper approach is as follows:

1.  Does the variant infringe any of the claims as a matter of normal interpretation?   

2.  If not, does the variant nonetheless infringe because it varies from the invention in a way or ways which is, or are, immaterial?

If the answer to either question is yes, there will be infringement.

The first question involves solving a problem of interpretation (according to applicable principles of document interpretation). The second question, concerning immaterial variants, however, involves more difficult questions of principle. Lord Neuberger revisited Lord Hoffman's three Improver questions, reformulating them as follows:

1.  Notwithstanding that it is not within the literal 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, i.e., the inventive concept revealed by the patent?  

2.  Would it have been 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 does so in substantially the same way as the invention? (emphasis added to show how this differentiates from the Improver formulation). 


In a case where there is no literal infringement, the patentee will need to establish that the answer to the first two questions is 'yes', and the answer to the third question is 'no'. 

In relation to the Actavis pemetrexed products, the reformulated questions were answered as follows:

1.  They worked in the same way as the invention, as they all ultimately involved a medicament containing the pemtrexed ions and vitamin B12, and therefore achieved substantially the same result in substantially the same way as the invention.   

2.  The notional addressee of the Patent would appreciate (and would have appreciated at the priority date) that each of the Actavis products would work in precisely the same way as pemetrexed disodium when included in a medicament with vitamin B12. This was a different approach to that of Arnold J and the Court of Appeal – applying the prior formulation of the second Improver question, they had considered that the notional addressee should not be treated as knowing that the Actavis products did in fact work at all, a test Lord Neuberger thought was too strict. 

3.  On the third question, the Court of Appeal had placed too much weight on the words of the claim. The addressee of the Patent would understand that the reason why the claims were limited to the disodium salt was because that was the only pemetrexed salt on which the experiments described in the specification had been carried out. However, this did not therefore mean that the patentee did not intend any other pemetrexed salts to infringe.  Given the common general knowledge, it was very unlikely that the notional addressee would have concluded that the patentee could have intended to exclude any pemetrexed salts other than pemetrexed disodium from the scope of protection.

Prosecution History

Actavis argued that the prosecution history of the Patent made it clear that the claims of the Patent should be interpreted as being limited to pemetrexed disodium. Lord Neuberger concluded that the UK courts should adopt a "sceptical, but not absolutist, attitude" to requests to take account of the prosecution file, similar to the approach of the German and Dutch courts. Accordingly, whilst there will be cases when justice may require reference to the contents of the file, the court will only rely upon the prosecution history to determine the extent of protection or scope of patent in limited circumstances.  For example, reference to the file would only be appropriate where (1) 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) it would be contrary to the public interest for the contents of the file to be ignored. One example would be where a patentee had made it clear to the EPO that it was not seeking to contend that the patent, if granted, would extend its scope to the sort of variant it now claimed infringed.

In this case, there was nothing in the prosecution file to justify departing from the provisional conclusion the Court had reached on direct infringement.

Indirect Infringement

Whilst it was not necessary to consider this aspect of the case, given the conclusion on direct infringement, the Supreme Court concluded that it would have upheld the Court of Appeal's determination that Actavis was liable for indirect infringement in the UK. 

French, Italian and Spanish designations

The Court reached the same conclusion on direct and indirect infringement in relation to the other relevant designations of the Patent. In the meantime, the approach in the decision of the Appeals Court in relation to the German designation of the Patent is awaited with interest.

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