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Regeneron 2.0: DNA sequencing, insufficiency and tea pots



United Kingdom

The Patent Court's recent decision in the Illumina v MGI case on the validity and infringement of patents concerning DNA sequencing is a must-read. Not only is it one of Birss J's last judgments before taking up his seat in the Court of Appeal, but also an important one in a number of respects.

In defending the infringement claim, MGI attacked Illumina’s patents on the basis that they were obvious and insufficient, which, however, only led to the invalidation of one out of five patents. In reaching this decision Birss J considered for the first time the applicability of the Regeneron Supreme Court ruling in 2020 to process claims and the alleged lack of sufficiency of the patents. When it came to the question of obviousness, determining who the skilled person in the art was also became a key issue of the case. Other interesting aspects of Birss J's judgment include his analysis of patents with interacting functions, and his remarks on the use of expert witnesses.

Recap of the Regeneron case

Regeneron Pharmaceuticals Inc v Kymab Ltd [2020] UKSC 27 was decided by the Supreme Court in June 2020 and concerned patents for types of a transgenic mouse used for the development of human antibodies (see our blog post). The key issue was whether the patentee had disclosed the invention clearly and completely enough for it to be performed by a person skilled in the art (section 72(1)(c) of the Patent Act 1977). This requirement comes from the legal principle that the monopoly, granted by the patent, should be justified by the technical contribution the disclosure of the invention has made to the state of art.

Lord Briggs (giving the majority judgment in the Supreme Court) set out eight principles to govern this concept of sufficiency. However, that action was about patents that dealt with a product and not with a process patent like in the case at hand.

Illumina's patents

Illumina's infringement action concerned five patents relating to DNA sequencing technology. The patents derive from work by Solexa, a spin out company from Cambridge University which Illumina bought in 2007.  The defendants (MGI) are all companies in the Beijing Genomics Institute group.  MGI seeks to sell DNA sequencing systems in the UK. Following a launch last year, MGI gave undertakings limiting UK sales until the trial.

The judgment

Skilled person in the art
According to established law, persons skilled in the art are those likely to have a real and practical interest in the subject matter of the invention. This concept applies in two different circumstances, namely devising the invention itself, as well as putting it into practice. There can be cases where there are two different persons skilled in the art for the same patent (following Schlumberger v EMGS [2010] EWCA Civ 819) namely:

  • One person is the person to whom the patent is addressed and whose attributes, skills and common general knowledge will be necessary to implement the patent; and
  • The second kind is the one relevant to obviousness.

In order to define the second kind of person one has to make sure to neither define that person too narrow, nor too widely to avoid unfairness to the inventor. Birss J struck a balance by defining a three-step approach (taking the wording from the judgment):

  1. To start by asking what problem does the invention aim to solve? 
  2. That leads one in turn to consider what the established field which existed was, in which the problem in fact can be located.
  3. It is the notional person or team in that established field which is the relevant team making up the person skilled in the art.


After delivering an improved approach to define the person skilled in the art, Birss J in the Patents Court redefined some of the principles establishes in the Regeneron case so that they could apply to patents that are concerned with methods as well as products. In one case, it was sufficient enough to substitute the word “make” with “perform” (principle 4 of Regeneron). For other principles (principles 5 – 7), the change had to go deeper and required a closer look at how the invention had to be disclosed in the patent.

Birss J considered that first, the two different kinds of ranges had to be distinguished before knowing what exactly the skilled person has to be enabled to do. One kind was described as a "relevant range" and the other kind was a range denominated by a "wholly irrelevant factor". For relevant ranges the law was that all types or embodiments across the scope of the claim, as that scope was denominated by that relevant range, had to be enabled. This will, however, not mean that the patent is insufficient simply because some choices within that range will not enable the invention. Therefore, defining the relevant range is the key element to determine whether a patent is invalid because of insufficiency.

In order to make this concept a bit more tangible, the judge used the example of a hypothetical patent for a non-dripping tea pot. This feature might be determined by its spout length and shape. The material on the other hand does not contribute to the patented function, but a suitable material would be essential to use the teapot as a container for liquid in the first place. Therefore, under the revised Regeneron principles, the spout length and the shape would be considered as a "relevant range" whereas the material of the teapot would be considered to be a "wholly irrelevant factor". This leads to the fact that a person skilled in the art would not have to be able to build a non-dripping teapot out of every material possible, as long as the made teapot was non-dripping and this could be done without undue burden.


One of the patents in dispute was concerned with so called rhodamine dye compounds, as well as conjugate molecules comprising those dyes used to label nucleotides, and methods for the use of these conjugates in sequencing by synthesis. MGI argued that the patent was invalid because it was obvious and claimed a mere collocation between the elements since they each acted independently of one another for the function they were already known for.

Birss J concluded that, this type of invention could be patented, if, in addition to the principles set out by the House of Lords in Sabaf v MFI [2004] UKHL 45, the new or improved result was the result of the relationship between the parts of the combination. Further, this interaction between the elements had to be taken into consideration by the designer of the product. This also means that section 3 of the Patents Act (obviousness) only applies to the combination and not to the individual parts of it.

Expert witnesses

Besides providing helpful guidance on the scope and validity of the patents, the judge also made some practical points about expert witnesses:

  • First, an expert witness can give evidence regardless of whether the witness has been working on the problem of the patent at the relevant time as long as the expert “gives candid and objective evidence” and does not argue the case for the party which has called it.
  • A deposition from one of the inventors of the patents in question cannot be used to establish the common general knowledge at the time of the invention since he is too involved in the invention.
  • If one of the parties plans to conduct a deposition virtually by video, they should allow sufficient time to prepare the technical requirements that are needed in order to ensure a hitchless hearing as possible.


Birss J concluded that four of the five Illumina patents were valid as amended and infringed by one or more of the MGI products. The fifth patent was invalid for lack of inventive step. (See [2021] EWHC 57 (Pat) for his judgment).

Key takeaways

This judgment of Birss J, reportedly his last before his well-deserved elevation to the Court of Appeal this month, is a substantial and important one to mark his departure from the Patents Court. This decision refines the insufficiency principles set out in the Regeneron ruling further in a clear and practical way and confirms that they are applicable to all patents – both product and process ones.

The decision also provides patent owners with a clearer picture of how to construct a claim that involves collocation. These guidelines should help patentees draft their claim more precisely and also emphasise the core reason a patent and the monopoly it comes with are granted – protection of the core invention while contributing to the state of art. It is unlikely, however, that this decision is going to be the last one in this area and more litigation is going to follow, particularly as there are a number of related ongoing proceedings between the parties around the globe. Watch this space…!
With special thanks to trainee, Fabia Breuer, for her contribution to this blog.

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