14 March 2022

T 1127/16: Is the EPO’s approach to claim interpretation at odds with the UK Courts’ principle of doctrine of equivalents?

The approach to claim interpretation taken by the European Patent Office (EPO)’s Technical Board of Appeal 3.5.03 in its recent decision T 1127/16 appears to be at odds with the UK Courts’ doctrine of equivalents, as recently applied in Illumina Cambridge Ltd v Latvia MGI Tech SIA & Ors [2021] EWHC 57.

UK Courts’ doctrine of equivalents

In the UK Supreme Court’s decision in Actavis v Eli Lilly [2017] UKSC 48, Lord Neuberger developed a new approach for dealing with “equivalents” in UK patent infringement. The decision set out a two-part approach to assessing whether a UK patent is infringed by a product or process that is an equivalent variant of that claimed in the patent. This approach involves asking the following two questions:

  • does the variant infringe any of the claims of the patent as a matter of normal interpretation; and, 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 is an infringement. Otherwise, there is not.

As an extension of the second question, Lord Neuberger set out three further questions (that have come to be known as the ‘Actavis Questions’) for evaluating whether a variant is ‘immaterial’:

  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?
  2. 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 does so in substantially the same way as the invention?
  3. 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?

The third Actavis question – Illumina Cambridge Ltd v Latvia MGI Tech SIA

The High Court of England & Wales applied the doctrine of equivalents principle in its recent decision in Illumina Cambridge Ltd v Latvia MGI Tech SIA, which related to DNA sequencing technology. 

One of the patents covered in this decision claimed a process involving ‘incorporation’ of a nucleotide. It was argued that this claim was infringed by the use of another process involving an allegedly equivalent variant of the claimed ‘incorporation’ step. 

However, the description of the patent contained a specific definition of the term ‘incorporation’ as referring to “(…) the joining of the nucleotide to the free 3’ hydroxyl group of the nucleic acid strand via formation of a phosphodiester linkage with the 5’ phosphate group of the nucleotide.” The allegedly equivalent incorporation step did not accord with this definition.

Based on this definition, the judge held that “(…) the answer to the third Actavis question should be in [the defendant’s] favour (…). The reason why skilled person would think that strict compliance with the normal construction of ‘incorporation’ was essential is because the specification has gone out of its way to define that term in a clear and simple way.  It is not necessary for the skilled person to speculate about why the patentee may have done that, the fact is that it has been done (Paragraph 396)”.

Therefore, in this decision, the description of the patent was used to impart a narrower interpretation of the claims of the patent, such that they were held to exclude the allegedly equivalent variant by virtue of the third Actavis question.

EPO decision T 1127/16

In this decision, the Technical Board of Appeal considered related issues of claim interpretation, taking an approach that appears to be at odds with the approach taken in the Illumina Cambridge decision.   

T 1127/16 was an appeal against a decision of the Opposition Division to revoke a European patent on the grounds that the main claim – as interpreted – extended beyond the content of the application as filed. The claim in question related to a method for handling aircraft communications involving communicating with the ground via a plurality of broadcast networks, arranged in an order of preference and stored within a preference list. The method involved evaluating the highest in preference broadcast network and whether it is available, before transmitting a message.  Importantly, the claim involved the following features:

  • “(…) evaluating a preference to determine a preferred network of the plurality of transmission networks,
  • wherein the preference comprises a preference list identifying a selection of the plurality of broadcast networks in order of preference
  • and identifying the highest in preference of the plurality of broadcast networks in the preference list that is available.”

One of the main questions of claim interpretation was whether features (b) and (c) should be read in combination or, as argued by the patentee, separately. If read in combination, the claim defined a preference list that identified both a selection of the plurality of broadcast networks in order of preference, and the highest in preference of the plurality of broadcast networks in the preference list that is available. The Opposition Division and Technical Board of Appeal both considered that there was no basis in the application as filed for such a preference list.

It was argued by the patentee during the appeal proceedings that the skilled person would consult the description to resolve this ambiguity, and that the description would clarify that in fact features (b) and (c) should be read separately, rather than together. 

However, the Technical Board of Appeal took a different approach, stating that “(…) the description and the drawings of the patent [do not] have to be consulted automatically as soon as an “ambiguous” feature (i.e. a feature which at least theoretically allows more than one interpretation) occurs in the claim, or where the claim as a whole includes one or more inconsistencies, to resolve that ambiguity or inconsistency. According to such a logic, an applicant could then arguably dispense with providing a clear and unambiguous formulation of claim features (…) in order to be able to fall back on a more description-based interpretation at will during a subsequent opposition proceedings.” (Reasons 2.6.1.)

The Board considered there to be no linguistic problem with reading features (b) and (c) together, and that the repeated use of the verb “identifying” in these features, as well as there being no comma separating these features, would lead the skilled person to read these two features together. The Board also considered this interpretation of the claim to be technically credible, setting out an exemplary implementation of the invention according to this interpretation. On this basis, the Board decided that the claim extended beyond the content of the application as filed and thus dismissed the appeal. 

The importance of commas?

Finally, much has been written about how the appeal in T 1127/16 failed as a result of the simple omission of comma between claims features (b) and (c), as set out above. The reality is, perhaps reassuringly, more nuanced.

The patentee in T 1127/16 did in fact file an auxiliary request in which a comma wasinserted between features (b) and (c). Considering this request, the Board nonetheless decided that “(…) despite the presence of the comma, the claim may – linguistically and technically – still be given the same meaning as (…) the main request”. (Reasons 3.2.)

Therefore, it is clear from the Board’s reasoning that they considered the presence or absence of comma between features (b) and (c) to be just one factor contributing to the way in which the claim should be interpreted. In practice, this factor was outweighed by others, such as the repeated use of the verb “identifying”, which were of more importance. 


The EWHC’s decision in Illumina Cambridge and the EPO Technical Board of Appeal’s decision in T 1127/16 illustrate differing approaches to using the content of the description of a patent to interpret the claims. 

In Illumina Cambridge, the EWHC relied on a definition provided in the description to interpret a key feature of the claim. This decision therefore highlights the potentially significant role the description can potentially play in interpreting the claims – particularly in the context of infringement proceedings – and therefore the care that should be taken when drafting the description, particularly with regard to any definitions of claim wording.

In T 1127/16, the Technical Board of Appeal took a more restrictive view of the role of the description in interpreting the claims, indicating that the description need not be consulted automatically, even when the claims are ambiguous when read in isolation. It is unclear how such an approach to claim interpretation would enable one to answer the third Actavis Question, which necessarily requires the claims to be read in the context of the whole patent to understand whether the reader would have concluded that strict compliance with the literal meaning of the claims was an essential requirement of the invention. Nonetheless, this decision serves as reminder as to the importance of drafting claims that are clear and unambiguous, independently from the description, and as to the potential effects of seemingly minor differences in claim wording.

Oliver Parish
Managing Associate