CA-2025-001040 - [2025] EWCA Civ 903

G 2/21

As explained in more detail below, some of AstraZeneca’s grounds of appeal concern the decision of the Enlarged Board of Appeal in case G 2/21 [2023] OJ EPO A85. This decision was rendered about four weeks before the hearing in Sandoz v BMS. I discussed it in my judgment in that case at [43]-[53]. Having regard to the arguments in this case, it is necessary to consider it afresh.

In G 2/21 the Enlarged Board of Appeal considered three questions about the circumstances in which it was permissible to rely on so-called “post-published evidence” (evidence which post-dates the application or priority date) as demonstrating or supporting a technical effect when assessing whether the claimed invention complies with the requirement for an inventive step.

In answering the questions referred, the Enlarged Board began by noting at [23] that, according to the settled jurisprudence of the Boards of Appeal, “the assessment of inventive step is to be made at the effective date of the patent on the basis of the information in the patent together with the common general knowledge then available to the skilled person”. To use a term employed by the Boards of Appeal in other contexts, this is the “gold standard”.

The Enlarged Board then noted at [24]-[26] that the EPO routinely employs the so-called “problem and solution approach” to the assessment of inventive step. It is not necessary for present purposes to describe this approach, but it is important to note that it forms an important part of the background to the questions referred to the Enlarged Board and that it is not employed by the courts of the UK (other than, on occasion, as a cross-check), nor is it widely employed by the courts of other EPC Contracting States.

The first question asked whether post-published evidence must be disregarded “on the ground that proof of the effect rests exclusively on the post-published evidence” (emphasis in the original). The Enlarged Board considered this question at [27]-[56]. Its answer was that “evidence submitted by a patent applicant or proprietor to prove a technical effect relied upon for acknowledgement of inventive step may not be disregarded solely on the ground that such evidence, on which the effect rests, had not been made public before the filing date of the patent and was filed after that date”. This is not really an answer to the question referred, which was not about whether evidence can be excluded solely on the ground that it post-dates the relevant date, but whether a technical effect can be relied upon which rests exclusively on post-dated evidence.

Perhaps for that reason, although the referring Board of Appeal only asked its second and third questions on the premise that the answer to the first question was yes, the Enlarged Board considered them anyway. In its decision to refer (T 116/18 Sumitomo/Insecticide compositions, unreported, 11 October 2021) the referring Board had identified what it regarded as two divergent lines of Board of Appeal case law. The first line, represented by decisions such as T 1329/04 Johns Hopkins/Factor-9 [2006] EPOR 8 and T 488/16 Bristol-Myers Squibb/Dasatinib [2019] EPOR 24, it labelled “ab initio plausibility”. The second line, represented by decisions such as T 578/06 Ipsen/Pancreaticcells (unreported, 29 June 2011), it labelled “ab initio implausibility”. The distinction it saw between these two lines was that, in the first, post-published evidence could be taken into account if, based on the information in the application and the skilled person’s common general knowledge, the skilled person would have considered the technical effect plausible. In the second line, post-published evidence could be taken into account if, based on the information in the application and the skilled person’s common general knowledge, the skilled person would not have considered the technical effect implausible.

The Enlarged Board began its consideration of these questions by observing at [58] that that it considered “the conceptional notion inherent in the term ‘plausibility’, which is often used as a generic catchword, as not being a distinct condition of patentability and patent validity, but a criterion for the reliance on a purported technical effect”. This observation chimes with what Lord Sumption said in Warner-Lambert at [23] and [36].

From [60] onwards, the Enlarged Board embarked on an analysis of the “jurisprudence regarding the reliance on a technical effect for inventive step”. It began with some “general considerations”, referring among other cases to Ipsen. At [66]-[68] it considered cases in the “ab initio plausibility” or “type I” line of case law identified by the referring Board, including Johns Hopkins and BMS/Dasatinib. In [69] it considered cases in the “ab initio implausibility” or “type II” line. It expressed its “intermediate conclusion” as follows:

The Enlarged Board takes note of the classification done by the referring board in respect of the case law of the boards of appeal concerning the relevance of post-published evidence to prove an asserted technical effect for acknowledgement of inventive step ...

However, when analysing the case law in more detail and irrespective of the conceptual terminologies for what questions 2 and 3 refer to as two distinct plausibility approaches, the Enlarged Board understands from the case law of the boards of appeal as common ground that the core issue rests with the question of what the skilled person, with the common general knowledge in mind, understands at the filing date from the application as originally filed as the technical teaching of the claimed invention.

Applying this understanding to the aforementioned decisions, not in reviewing them but in an attempt to test the Enlarged Board’s understanding, the Enlarged Board is satisfied that the outcome in each particular case would not have been different from the actual finding of the respective board of appeal. Irrespective of the use of the terminological notion of plausibility, the cited decisions appear to show that the particular board of appeal focussed on the question whether or not the technical effect relied upon by the patent applicant or proprietor was derivable for the person skilled in the art from the technical teaching of the application documents.”

In other words, the Enlarged Board regarded the two lines of case law as being reconcilable. In each case, the core question being addressed was what the technical teaching of the application was to the skilled person with the common general knowledge in mind at the filing date, and whether the technical effect relied upon by the patent applicant or proprietor was derivable from that technical teaching.

Although the reference was only concerned with inventive step, at [73]-[77] the Enlarged Board considered the case law of the Boards of Appeal regarding sufficiency, in particular in the context of second medical use claims. It noted at [74] that the issues of sufficiency of disclosure (Article 83) and inventive step (Article 56) were “to be treated separately”. It also noted that in second medical use cases a technical effect, usually a therapeutic effect, was a feature of the claim and that such cases involved the use of a known therapeutic agent for a new therapeutic application. It was therefore “necessary that the patent … renders it credible that the known therapeutic agent … is suitable for the claimed therapeutic application”.

The Enlarged Board expressed its “intermediate conclusion” with regard to these cases at [77] as follows:

“The reasoned findings of the boards of appeal in the decisions referred to above make clear that the scope of reliance on post published evidence is much narrower under sufficiency of disclosure (Article 83 EPC) compared to the situation under inventive step (Article 56 EPC). In order to meet the requirement that the disclosure of the invention be sufficiently clear and complete for it to be carried out by the person skilled in the art, the proof of a claimed therapeutic effect has to be provided in the application as filed, in particular if, in the absence of experimental data in the application as filed, it would not be credible to the skilled person that the therapeutic effect is achieved. A lack in this respect cannot be remedied by post-published evidence.”

At [78]-[85] the Enlarged Board turned to consider decisions of courts of EPC Contracting States “with regard to the reliance on technical effect for inventive step”. In particular, at [84]-[85] it considered judgments of the UK courts, including Warner-Lambert and the High Court judgment in Sandoz v BMS. It expressed its “intermediate conclusion” as follows:

Like the EPC, none of the legal systems of the EPC Contracting States provide for an explicit patentability requirement for what the referring decision discusses and addresses with what is referred to in questions 2 and 3 under the term ‘plausibility’.

Notwithstanding the fact that the aforementioned decisions were taken on the decisive facts of the case in hand and the particular submissions made by the parties to those proceedings, the Enlarged Board recognises a certain degree of common ground that the courts of the EPC Contracting States, when confronted with the examination of an asserted technical effect in the assessment of inventive step and with the question whether a patent proprietor may rely on post-published evidence to confirm that technical effect, ponder on the technical teaching of the claimed subject-matter that the person skilled in the art, with the common general knowledge in mind, understands from the patent application.”

In other words, the Enlarged Board interpreted the decisions of the national courts as approaching matters in a similar manner to the Board of Appeal decisions which it had summarised in [71]-[72].

At [88]-[95] the EBA set out its “concluding considerations”, including the following:

The term ‘plausibility’ that is found in the case law of the boards of appeal and relied upon by the referring board in questions 2 and 3 of the referral and the reasons for it, does not amount to a distinctive legal concept or a specific patent law requirement under the EPC, in particular under Article 56 and 83 EPC. It rather describes a generic catchword seized in the jurisprudence of the boards of appeal, by some national courts and by users of the European patent system.

The relevant standard for the reliance on a purported technical effect when assessing whether or not the claimed subject-matter involves an inventive step concerns the question of what the skilled person, with the common general knowledge in mind, would understand at the filing date from the application as originally filed as the technical teaching of the claimed invention. The technical effect relied upon, even at a later stage, needs to be encompassed by that technical teaching and to embody the same invention, because such an effect does not change the nature of the claimed invention.

Hence, 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 consider said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention.

The Enlarged Board is aware of the abstractness of some of the aforementioned criteria. However, apart from the fact that the Enlarged Board, in its function assigned to it under Article 112(1) EPC, is not called to decide on a specific case, it is the pertinent circumstances of each case which provide the basis on which a board of appeal or other deciding body is required to judge, and the actual outcome may well to some extent be influenced by the technical field of the claimed invention. Irrespective of the actual circumstances of a particular case, the guiding principles set out above should allow the competent board of appeal or other deciding body to take a decision on whether or not post-published evidence may or may not be relied upon in support of an asserted technical effect when assessing whether or not the claimed subject-matter involves an inventive step.”

Accordingly, the Enlarged Board answered the second and third questions in its order as follows:

“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 the said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention.”

It is clear, and undisputed by either party in the present case, that, in expressing itself in the way that it did, the Enlarged Board was deliberately eschewing the language of plausibility. What is less clear is whether the test it laid down differs in substance from one of plausibility, and if so how. There is a substantial dispute as to how that test is to be understood and applied. It is common ground that the test appears to involve two limbs: the skilled person would derive the technical effect as being, first, encompassed by the technical teaching of the application, and secondly, embodied by the same originally disclosed invention. The dispute particularly focusses on the second limb.