Enlarged Board of Appeal to tackle the "Humpty Dumpty-ish" plausibility question (G2/21)

As expected, the Board of Appeal in T 116/18 has now referred to the Enlarged Board of Appeal (EBA) questions on the use of post-filed evidence to establish plausibility for an invention. The referral (G2/12) is confirmed in the Board of Appeal's decision in T 116/18 and is also summarised in an EPO press release (here). The Board of Appeal decision makes for an interesting read, as it explores the legal basis (or lack of) for plausibility in the case law and the EPC itself. The Board of Appeal goes so far as to quote the view of Sir Robin Jacob that deriving the plausibility requirement from the EPC strains the meaning of words to breaking point. G2/21 will be closely watched by many, given the potential ramifications of the EBA's answer on the required evidence threshold for patent validity. 

Case Background

The opposition case from which the referral stems relates to the validity of patent EP2484209 for an insecticide. In support of the invention, the patent provided data demonstrating the synergistic effect of example compounds falling under the scope of the claim against two different species of moth (S. litura  and P. xylostella). 

The Opponent submitted their own data, showing that compounds falling under the scope of the claim did not have synergistic effect against P. xylostella. In response, the Patentee submitted additional data showing a synergistic effect of the example compounds against another species of moth (C. suppressallis). The Opponent argued that the synergistic effect of the compounds against C. suppressallis had not been made plausible in the application as filed. As such, it was argued, the post-published evidence should not be taken into account.

The Board of Appeal decision

When a technical feature is included in the claim, plausibility is considered under the heading of sufficiency (Article 83 EPC). When a technical feature is not in the claim but relied on for inventive step in the problem solution approach, the plausiblity of the feature is considered as a part of inventive step (Article 56 EPC). In the case in question, the issue of plausibility was considered under the heading of inventive step, given that the technical effect of synergism was not a feature of the claim but an effect relied on for inventive step (G1/03). Notably, however, the referring Board of Appeal considered the question surrounding the admissibility of post-published evidence to be as relevant to sufficiency as inventive step (r. 13.3.1). 

The post-published data submitted by the patentee were considered fundamental to deciding the question of inventive step. Particularly, in the absence of the additional data, the Board of Appeal (3.3.02) found that the problem solved by the invention was the provision of a synergistic insecticide activity against the species of moth for which data were provided in the patent. Without the additional data, the Board of Appeal found that the claimed invention did not plausibly solve this problem, given that data provided by the Opponent convincingly contradicted the data in the patent (r. 12.4.9). 

Conversely, if the patentee's additional data were taken into account, the Board of Appeal found that the objective technical problem to be solved in view of the prior art could be revised as the provision of an synergistic insecticide activity against C. suppressallis, i.e. the moth species to which the new data related. None of the data submitted by the Opponent contradicted the Patentee's post-published data relating to this moth species. 

Consequently, if the Patentee's post-published evidence was taken into account for inventive step, the objective technical problem to be solved in view of the prior art could be reformulated (as the provision of a synergistic insecticide against C. suppressallis), and inventive step acknowledged. 

Three lines of diverging case law on plausibility

In the view of the Board of Appeal, their exists 3 diverging lines of case law on the the admissibility of post-published evidence for inventive step (Article 112 EPC) (IPKat): 1) Ab initio plausibility, 2) Ab initio implausibility, and 3) No plausibility. 

According to the ab initio plausibility case law, plausibility must be established in the application as filed (T 1329/04, T 609/02, T 488/16, T 415/11, T 1791/11 and T 895/13), i.e. in the form of direct evidence for the technical effect relied on for inventive step. 

By contrast, in the ab initio implausibility line of case law, post-published evidence can only be disregarded if the skilled person had reasons to doubt (e.g. from common general knowledge) that the purported technical effect had in fact been achieved at the filing date. In other words, according to this case law, post-published evidence should be taken into account if the purported technical effect is not implausible (r. 13.5) (T 919/15, T 536/07, T 1437/07, T 266/10, T 863/12, T 184/16, T 2015/20). The test is whether there was substantiated doubt at the filing date. The Board of Appeal also placed the UK Supreme Court decision in Warner Lambert (IPKat) in this category (as discussed by IPKat at the time). 

The final line of case law on plausibility, is that according to which no plausibility is required (T 31/18, T 2371/13). According to these decisions, the requirement for plausibility of a technical effect at the filing date is incompatible with the problem solution approach. 

In view of the diverging lines of case law, the Board of Appeal concluded that a referral on plausibility was clearly needed. The referred questions relate to the three lines of case law outlined by the Board of Appeal. In summary, the Board asks: If inventive step relies on post-published evidence, 1) should post-published evidence be disregarded if proof of the technical effect is solely provided by the post-published evidence. If the answer to (1) is yes, can the post-published evidence be taken into account if 2) the technical effect was plausible at the filing date (ab initio plausibility); or 3) the technical effect was not implausible at the filing date (ab initio implausibility). The referred questions are provided in full below. 

Final Thoughts

How would Humpty-Dumpty
define the plausibility requirement?

The Board of Appeal noted that in all the decisions requiring the higher bar of ab initio plausibility (including Warner Lambert), plausibility was denied. By contrast, in all of the cited decisions in the ab initio implausibility line, plausibility was acknowledged. This difference highlights the implications that a EBA decision in this referral may have on the requirements for patentability and how broadly an invention may be claimed based on the data provided in the application as filed. 

The Board of Appeal in the referring decision appeared to disagree with the "no plausibility" line of case law, noting that it would permit armchair inventors to claim whatever they thought that it might be possible to prove later (r. 13.7.1). On the other hand, the Board of Appeal also appeared uncomfortable with denying patentees the option of reformulating the objective technical problem to be solved in view of the closest prior art, in view of "decades of case law" permitting this (r. 13.7.2). However, if it is acknowledged that the objective technical problem to be solved may be reformulated, the Board of Appeal in the referring decision agreed that an undue burden would be placed on the patentee to plausibly demonstrate, at the filing date, the technical effect of the invention in view of all possible closest prior art. 

Perhaps, as the referring Board of Appeal cautiously suggests, "it may be questionable whether Article 56 EPC is a proper legal basis for plausibility" (r. 13.7.4). It may be that any attempt to align the case law on problem-solution and plausibility will inexorably leads to the conclusion that plausibility can only be properly considered under the umbrella of sufficiency (Article 83 EPC), and not inventive step (Article 56 EPC). Even more radically, the Board of Appeal noted the opinions of various commentators that plausibility may lack any legal basis in the EPC, and is a solely court-invented pre-condition to validity. The Board of Appeal particular quoted Sir Robin Jacob on the topic, who observed that: "If one actually looks at the words of the EPC a purist would say it is straining the meaning of words beyond breaking point to get plausibility out of them - positively Humpty Dumpty-ish" (i.e. the Humpty Dumpty of Lewis Carroll's Alice through the looking glass: "'When I use a word', Humpty Dumpty said in rather a scornful tone, 'it means just what I choose it to mean—neither more nor less.'"). 

It does seem that, the closer one looks at the issue of plausibility, the thornier the questions become. In answering G2/21, the Enlarged Board of Appeal will certainly have its work cut out for it in reconciling the contradictions in the case law as it stands. 

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The referred questions

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)?

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Further reading

10 Aug 2021: New referral expected to the EBA on the use of post-published data to support inventive step

21 Sep 2021: Reasons for an EBA referral on plausibility, post-published evidence and problem-solution