Patents and Plausibility - G2/21 Syngenta Ltd v Sumitomo Chemical Co. Ltd.

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Jane Lambert

Enlarged Board of Appeal (C. Josefsson, I. Beckedorf, F. Blumer, T. Bokor, P. Catallozzi, P. Gryczka and A. Ritzka) G 0002/21 Syngenta Ltd v Sumitomo Chemical Co. Ltd 23 March 2023

European patent No. 2 484 209  ("the patent") has been granted to Sumitomo Chemical Co. Ltd. ("Sumitomo") for a mixture of thiamethoxam and other compounds in accordance with a formula disclosed in the specification.  That mixture produces an insecticidal activity that is greater than would be achieved by any of those compounds administered on its own ("the invention"). Syngenta Limited ("Syngenta") objected to the patent on the grounds that the invention was not new or obvious, that it had not been properly disclosed and it included added matter.

The European Patent Convention ("EPC") provides a procedure for the revocation of a patent known as "opposition."   Art 99 (1) of the EPC enables anybody who objects to a patent to give notice of opposition to the European Patent Office ("EPO")  within 9 months of the grant.  The grounds for opposition are set out in art 100:

"(a)  the subject matter of the European patent is not patentable under Articles 52 to 57;
(b) the European patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art;
(c) the subject matter of the European patent extends beyond the content of the application as filed, or, if the patent was granted on a divisional application or on a new application filed under Article 61, beyond the content of the earlier application as filed."

Oppositions are considered by an organ of the EPO known as an "Opposition Division"  (see art 19 (1) of the EPC).  A party that is dissatisfied with a decision of an Opposition Division may appeal to a tribunal established by art 21 known as a "Board of Appeal".   If a Board of Appeal requires guidance on a point of law it may refer the point to an Enlarged Board of Appeal pursuant to art 22 (1) (a) and art 112 (1).  There is no equivalent to opposition in the UK Patents Act 1977. 

Syngenta opposed the grant under art 99 on all the grounds in art 100.  The Opposition Division rejected the opposition so Syngenta appealed to the Technical Board of Appeal.  The appeal came on before the Board  (M. O. Müller, A. Lenzen and P. de Heij) on 11 Oct 2021.  The case is referred to as T 0116/18. 

The Technical Board was satisfied that there had been sufficient disclosure of the claimed invention. It decided that the question of whether any synergy could be achieved should be assessed under art 100 (a) and art 56 of the EPC rather than art 100 (b). In respect of want of novelty, the Board was satisfied that none of the prior art disclosed by the opponent had anticipated the invention. As for obviousness, the Board reasoned that the assessment of the inventive step of the subject matter of the patent hinged on whether evidence not published before the filing date of the patent and made available after that date could be taken into consideration in view of the so-called plausibility case law. That was because the patentee relied on evidence that had come to light after the publication of the patent application. Both parties lodged opposing requests as to whether such evidence should be taken into consideration.

As there were conflicting lines of authority on the issue, the Technical Board referred the following questions to the Enlarged Board of Appeal:

"If for acknowledgement of inventive step the patent proprietor relies on a technical effect and has submitted evidence, such as experimental data, to prove such an effect, this evidence not having been public before the filing date of the patent in suit and having been filed after that date (post-published evidence):

1. Should an exception to the principle of free evaluation of evidence (see e.g. G 3/97, Reasons 5, and G 1/12, Reasons 31) be accepted in that post-published evidence must be disregarded on the ground that the proof of the effect rests exclusively on the post-published evidence?
2. If the answer is yes (the post-published evidence must be disregarded if the proof of the effect rests exclusively on this evidence), can the post-published evidence be taken into consideration if, based on the information in the patent application in suit or the common general knowledge, the skilled person at the filing date of the patent application in suit would have considered the effect plausible (ab initio plausibility)?
3. If the answer to the first question is yes (the post-published evidence must be disregarded if the proof of the effect rests exclusively on this evidence), can the post-published evidence be taken into consideration if, based on the information in the patent application in suit or the common general knowledge, the skilled person at the filing date of the patent application in suit would have seen no reason to consider the effect implausible (ab initio implausibility)?"

According to para 4.1 of Part G of the Rules Common to all Proceedings before the EPO, the principle of "free evaluation of evidence" is that there are no rules as to the types of evidence that are, or are not, convincing. Neither the EPO nor any of the case law sets out formal rules for the evaluation of evidence. Boards of Appeal and other organs of the EPO may assess whether a fact is established on a case-by-case basis. 

It would appear that the Technical Board asked questions 2 and 3 because there was some doubt as to the plausibility of the invention.  Plausibility is not a requirement for the grant of a patent under either EPC or the UK Patents Act 1977.   It was described by the Board as "a generic catchword seized in the jurisprudence of the boards of appeal, by some national courts and by users of the European patent system at para 92 of its reasons.   

However, there are circumstances when the issue becomes relevant. As Lord Sumption explained in para [19] of Warner-Lambert Company LLC v Generics (UK) Ltd (t/a Mylan) and another [2018] UKSC 56, [2019] Bus LR 360, (2019) 165 BMLR 14, [2018] RPC 21, [2019] 3 All ER 95:

"Section 14 of the Patents Act and the corresponding provisions of the EPC assume that an invention will be sufficiently disclosed if the specification enables it to be “performed”. In the case of a patent for a new product or process, that assumption is almost always correct. The skilled person will discover that it works by replicating it in accordance with the specification. But the assumption is not correct in the case of a second use patent. The invention is not the compound or the process of its manufacture. The skilled person already knows how to make the product from the prior art disclosed in the original patent. The invention consists in the new purpose for which the product is to be manufactured. If sections 14 (3) and 72 (1) (c) are read literally and as an exhaustive statement of the requirement of sufficiency, all that needs to be disclosed is the new purpose, which is enough to enable it to be administered to a patient suffering from the relevant condition. The skilled person does not need to know how or why the invention works in order to replicate it. The result would be that the knowledge which made the identification of the new purpose inventive need not be disclosed at all."

His lordship observed in the next paragraph:

"The main problem about this result is that it would enable a patent to be obtained on a wholly speculative basis. Without some disclosure of how or why the known product can be expected to work in the new application, it would be possible to patent the manufacture of known compounds for the purpose of treating every conceivably relevant condition without having invented anything at all, in the hope that trial and error might in due course show that the product was efficacious in treating at least some of them."

The EPO is aware of this problem. In fact, Lord Sunmption said at para [23] of his judgment that "the concept of plausibility originates in the case law of the EPO as a response to over-broad claims, in particular claims to whole classes of chemical compounds supported by a description which fails to show which compounds can be expected to work."  

The Enlarged Board of Appeal took question 1 of the Technical Board's questions first.  After reviewing its case law and the rules of evidence in the courts of England and Wales, France, Germany, the Netherlands and Switzerland the Board held at para 55 of the reasons that the principle of free evaluation of evidence qualifies as a universally applicable principle in assessing any means of evidence by a board of appeal. There was one important exception to this "universally accepted principle" in that the principle of free evaluation of evidence does not exist in England's common law system.   Nevertheless, in view of the adoption of the principle just about everywhere else, the Board concluded at para 56 that:

"evidence submitted by a patent applicant or proprietor to prove a technical effect relied upon for acknowledgement of the inventive step of the claimed subject matter may not be disregarded solely on the ground that such evidence, on which the effect rests, had not been public before the filing date of the patent in suit and was filed after that date."

It is important to stress that not disregarding evidence submitted by a patent applicant or proprietor to prove a technical effect relied upon for acknowledgement of the inventive step of the claimed subject matter solely on the ground that such evidence, on which the effect rests, had not been public before the filing date of the patent in suit and was filed after that date did not mean that a patent applicant or patentee could rely solely on such evidence.   Para 25 of the Board's reasons made clear that the technical problem to be solved by the invention had to be derived from effects directly and causally related to the technical features of the claimed invention.  The Board continued:

"An effect could not be validly used in the formulation of the technical problem if the effect required additional information not at the disposal of the skilled person even after taking into account the content of the application in question...."

The Enlarged Board did not need to address the second or third questions that had been referred to it because it had answered the first in the negative.  However, it offered guidance on the application of the principle of free evaluation of evidence in respect of post-published evidence for reliance on a purported but contested technical effect at the request of the parties and the President of the EPO. 

After considering the boards' previous decisions and the case law of England and Wales, France, Germany, the Netherlands and Switzerland, the Enlarged Board gave the Technical Board of Appeal the following further answer:

"A patent applicant or proprietor may rely upon a technical effect for inventive step if the skilled person, having the common general knowledge in mind, and based on the application as originally filed, would derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention."

It follows that the circumstances in which an applicant for a patent or patentee can rely on matter published after the filing date are limited.   In practical terms the difference between the position in England and that at the EPO may not be great.

The Enlarged Board does not function as a court of appeal in cases such as this.  It is much more like the Court of Justice of the European Union when determining an issue of EU law upon a preliminary reference from a national court pursuant to art 267 of the Treaty on the Functioning of the European Union.  In due course, the appeal against the Opposition Division's decision will go back to the Technical Board of Appeal. In deciding this appeal the Technical Board is likely to have something to say about the plausibility of the invention in relation to whether it involves an inventive step.

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