The European Patent Convention and the Patents Act 1977 both require that a patent application disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art.

This means the skilled person must be able to carry out the invention using the information disclosed in the patent, with the common general knowledge available at the priority date, without having to undertake further experimentation or make further inventions of their own. This requirement comes from the legal principle that the monopoly afforded by the grant of a patent should be justified by the technical contribution the disclosure of the invention has made to the state of art.

As reported last year (here), in Regeneron v Kymab ([2020] UKSC 27), the UK Supreme Court (UKSC) decided that two of Regeneron’s patents relating to transgenic mice were invalid for lack of sufficient disclosure. In its decision, the UKSC was clear that claims are not sufficiently enabled if all of the embodiments can only be put into practice at a date after the priority date. Specifically, Regeneron’s claims lacked sufficiency because the disclosure of the patents did not enable the making of a mouse which incorporated any more than a small part of the human variable region, yet claimed a monopoly including mice incorporating a far greater quantity of the human variable region.

The Regeneron judgement set out eight principles to govern the concept of sufficiency. However, many of these principles refer explicitly to products or product claims.

Following the Regeneron decision, there was some concern that the English courts would be more willing to find patents invalid for a lack of sufficiency in the future. The recent High Court decision in Illumina v MGI ([2021] EWHC 57 (Pat)) was the first UK case since Regeneron to consider the issue of sufficiency and therefore provides us with some guidance as to how the principle set out in Regeneron will be applied.

Illumina’s infringement action against MGI concerned five patents relating to DNA sequencing technology. In response, MGI mounted various invalidity attacks including insufficiency applying the principles of Regeneron. Despite these sufficiency attacks, four of the five Illumina patents were held to be valid.

In his judgement, Mr Justice Birss considered that the only features requiring enablement over the entire scope of the claim according to the principles set out in the Regeneron decision are those relating to the core inventive concept of the claim. This point was helpfully illustrated by Mr Justice Birss using a hypothetical patent claiming a new type of teapot:

To take an example mentioned in argument in this case, say an inventor invented a new teapot which was inventive and useful because its spout was shaped in a new way so as not to drip. The claim would be to a teapot with the spout shaped in that special way. The claim might well not say anything about the material from which to make the teapot, because it is irrelevant to the invention. … Now the patent needs to enable the skilled person to make the product. In the example I will assume the skilled person could choose, identify and test suitable materials at the priority date without an undue burden. China would work and 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 teapot patent’s priority date. Furthermore in my judgment this fact, that the claim covers types of teapot which it does not enable, does not reveal some insufficiency. 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. However note the potential for error here. The material from which a teapot is made is plainly crucial to its function as a teapot. There are materials which are not suitable to use for teapots.

That is not the kind of relevance which Regeneron is referring to. Relevance in the Regeneron sense is a much more particular concept which depends on examining all the circumstances, and depends not simply on the invention (that is to say the claim as drafted) but also on what I can only think of calling the essence or core of that invention (closely related to the technical contribution and/or the inventive concept). Although the invention in this example is (by definition) a teapot since that is what is claimed (s125, 1977 Act), nevertheless the value, utility and purpose referred to by Lord Briggs in principle (vii) are concepts which in this example would be focussed on the shape of spout.

So, according to Mr Justice Birss, a crucial part of the sufficiency analysis is determining which elements of a claim must meet the sufficiency requirements set out in Regeneron. These relevant features are those relating to the “essence of the invention”.

The “essence of the invention” is a concept that we are seeing increasingly in judgements from the English courts as well as in other jurisdictions. However, the difficulty with it is that the “essence of the invention” may not always be clear. Also, what is considered to be the “essence of the invention” when a patent application is drafted may well be different to when the patent is granted. It may change once again if and when the patent is litigated.

Nevertheless, the Illumina judgement will be welcomed by many as a reasonable and practical application of the sufficiency principles provided by Regeneron.

This recent English case law on the requirement to sufficiently disclose the invention is a reminder to practitioners to take care to identify what the technical contribution of an invention is when drafting patent applications. It is important to ensure that there is clear disclosure of embodiments that are technically possible, with particular care being taken in relation to features that might be considered to relate to the “essence of the invention”.