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Patents Court applies Supreme Court's Regeneron sufficiency principles

Posted on 24 March 2021

In June 2020 we reported on the decision in Regeneron v. Kymab in which the Supreme Court articulated a set of general principles applicable to sufficiency, the rule of law which requires that a patent application discloses the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (see Article 83 of the EPC and section 14(3) UK Patents Act 1977). Insufficiency of disclosure is a ground for invalidity of a granted patent (section 72(1)(c) Patents Act 1977).

In the Supreme Court, Lord Bridge (giving the leading judgment) set out eight principles of general application including the following (using the Roman numbering of the Supreme Court):

  1. A claim which seeks to protect products which cannot be made by the skilled person using the disclosure in the patent will, subject to de minimis or wholly irrelevant exceptions, be bound to exceed the contribution to the art made by the patent.
  2. This does not mean that the patentee has to demonstrate in the disclosure that every embodiment within the scope of the claim has been tried, tested and proved to have been enabled to be made. Patentees may rely, if they can, upon a principle of general application if it would appear reasonably likely to enable the whole range of products within the scope of the claim to be made. But they take the risk, if challenged, that the supposed general principle will be proved at trial not in fact to enable a significant, relevant, part of the claimed range to be made, as at the priority date. 
  3. A claim which in substance passes the sufficiency test will not be defeated by dividing the product claim into a range denominated by a wholly irrelevant factor (e.g. the length of a mouse's tail). The requirement to show enablement across the whole scope of the claim applies only across a relevant range. Broadly, a range will be relevant if it is denominated by reference to a variable which significantly affects the value or utility of the product in achieving the purpose for which it is to be made.
  4. Enablement across the scope of a product claim is not established merely by showing that all products within the relevant range will, if and when they can be made, deliver the same general benefit intended to be generated by the invention, regardless of how valuable and ground-breaking that invention may prove to be. 

On 20 January 2021, Mr Justice Birss delivered a 520 paragraph judgment in Illumina Cambridge Limited (Illumina) v. Latvia MGI Tech SIA and others (MGI), the first decision following Regeneron to apply the Supreme Court's decision. Although this monster judgment considered others issues of validity (notably inventive step) and also infringement, this note focuses on the Court’s decision on “Regeneron insufficiency”.


The Defendants, MGI – all companies in the Beijing Genomics Institute group – intended to sell DNA sequencing systems in the UK. Illumina alleged that such systems infringed a number of its patents, three of which claimed modified nucleotides for use in DNA sequencing. MGI counterclaimed that claims to modified nucleotides were insufficient because the relevant specifications did not enable the skilled person to perform a sequencing method across the breadth of the claim without undue burden.

MGI focused on two issues:

  • Read length: MGI alleged that a claim to a method for determining the sequence of a target single stranded nucleotide was open ended in terms of the length of the nucleotide to be sequenced and that the data in the patent only presented results for a limited number of cycles; and
  • “Impractical linkers”: MGI alleged that the claim in issue covered methods of sequencing using nucleotides, linkers and labels that would not enable the skilled person to perform a sequencing method across the breadth of the claim without undue burden.

The first issue which Birss J considered was whether and how Regeneron applied to method claims (given that Regeneron was concerned with the sufficiency of a product claim). The judge held that the principles laid down in Regeneron were not limited to product claims, although he observed that there was a need to reformulate the principles (which the judge duly did) to cover the performance of a process (as opposed to the making of products).

Next, the judge considered the key issue of ranges (principle (vii) – set out above - of the Supreme Court’s judgment). Birss J held that the identification of the purpose which will be taken into account in distinguishing between the two kinds of range will be a matter of construction of the specification through the eyes of the skilled person imbued with the common general knowledge, whilst the product or process whose utility or value is to be considered will be the claimed product or process. Birss J observed that any descriptive or functional language will inevitably cover a variety of things and therefore will encompass “what one could call a range”. Therefore, it will be necessary to consider whether such a range is a relevant one in the Regeneron sense:

If it is a relevant range then the consequences in Regeneron will follow if it is not enabled across the whole range (subject to de minimis exceptions) and the presence of a type or embodiment within that range which cannot be performed at the relevant date will be fatal even though, if it was able to be performed years later, it could be said to draw on the technical contribution made by the inventors. However if the range is not a relevant range then no difficulty of that kind arises. (paragraph 276)

Birss J illustrated the point using the hypothetical example of a new teapot which was inventive and useful because its spout was shaped in a new way so as not to drip. The claim might well not say anything about the material from which to make the teapot, because it is irrelevant to the invention. Whilst the patent needs to enable the skilled person to make the product, it can be assumed that he or she could choose, identify and test suitable materials at the priority date without an undue burden (e.g. china would work, chocolate would not). However the claim would be infringed later on even if a teapot was made using a new inventive form of Pyrex glass which had not been invented at the patent’s priority date. As the judge observed “The fact that the skilled person could not make such a teapot at the priority date of the teapot patent does not matter. What does matter is that the descriptive feature of the claim, which is at least implicit in the claim, that the teapot has to be made of a suitable material, is not a relevant range in the Regeneron sense.” In this example the value, utility and purpose referred to in principle (vii) of Regeneron are concepts which would be focussed on the shape of spout i.e. what Birss J referred to as the essence or core of the invention.

Drawing these principles together Birss J summarised the position as follows:

  1. When examining any aspect of claim scope for the purposes of the enablement it is necessary to distinguish between ranges relevant in the Regeneron sense and other ranges. 
  2. For ranges relevant in the Regeneron sense, to be sufficient, there must be enablement across the whole scope of the claim within that relevant range (subject to de minimis exceptions) at the relevant date. If a type or embodiment within such a range is not enabled at that date then the fact it could be made later, as a result of further developments not enabled by the patent, even though it never could have been made without the invention, will not save the claim from insufficiency.
  3. Not all claims will necessarily contain a range relevant in the Regeneron sense but if they do, then this principle applies to that range.
  4. An example of an other range, not relevant in the Regeneron sense, will be a descriptive feature in a claim (whether structural or functional) which can cover a variety of things, but for which that variety does not significantly affect the value or utility of the claimed product or process in achieving its relevant purpose. The relevant purpose is judged in all the circumstances, starting from the terms of the claim itself but also, where appropriate, by reference to the essence or core of the invention.
  5. For a claim feature which amounts to a range in this other sense, the skilled person must still be able to make a suitable selection, without undue burden, in order for the claim to be sufficiently disclosed. However provided that is so at the relevant date, such a claim feature will not be insufficient simply because it is capable of also covering within its scope things which had not been invented at that relevant date.
  6. When examining enablement of any kind, the test is always about what the skilled person is able to do without undue burden. The patentee is entitled to expect that the skilled person, in seeking to make the invention work, will exercise that skill. If need be that exercise will involve testing and experiments, as long as it is not unduly burdensome.

Applying these principles to “read length” and “impractical linkers”, the judge held they were not relevant ranges applying Regeneron. In relation to the former the judge held that read length was not a variable which significantly affected the value or utility of the claimed process in achieving the purpose for which that process was to be performed; in relation to the latter he held that whilst the particular nucleotide, polymerase, linker, label and cleavage conditions chosen have to be suitable, beyond that their individual type does not significantly affect the value of the method to achieve the purpose for which it is being carried out. Further, in each case the skilled person could identify workable methods at the priority date without undue burden. The insufficiency challenge therefore failed.

Concluding Comments

The facts and complexities of Illumina provided the Court with an opportunity to apply the Regeneron principles, an opportunity which the judge – in his final judgment prior to his elevation to the Court of Appeal – took with both hands. As the application of Regeneron evolves in the Patents Court it is inevitable that we will see disputes concerning “Regeneron insufficiency” revolve around arguments over what is or is not the essence or core of the invention and whether the variable significantly affects the value or utility of the claimed product or process.


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