Plausibility - EPO stays proceedings in view of Enlarged Board Referral

The European Patent Office has announced a stay of all examination/opposition proceedings involving applications/patents in which the assessment of inventive step is exclusively based on evidence that was not publicly available before the filing date, and in which the decision depends entirely on the outcome of Referral G2/21 (Plausibility), until after the Enlarged Board has issued its decision.

The issue of "Plausibility" has become a hot topic at the EPO. It can be relevant to both sufficiency of disclosure and inventive step.

In the matter considered in T116/18(relating to EP 2 484 209), the patent in question included data showing a synergistic effect of insecticidal compounds against two species of moth.The Opponent submitted evidence that compounds falling within the scope of the claim did not, in fact, have synergistic effect against one of those species.The Patentee then tried to rely upon post-filed evidence demonstrating a synergistic effect against a third species of moth in support of inventive step.

The Opponent argued that, as this effect had not been made plausible in the application as filed, the post-published evidence should not be taken into account.

In considering inventive step, the Board found that without the post-filed data, the invention did not plausibly solve the problem of providing synergistic activity against the two moth species for which data were provided in the patent.This is because the Opponent had provided evidence that convincingly contradicted the data in the patent.However, as the Opponent's data did not contradict the post-filed data, taking the post-filed data into account could allow for a reformulation of the problem to be solved and allow inventive step to be acknowledged.

In the Board's view there are three diverging lines of case law:

1) ab initio plausibility – in which plausibility must be established in the application as filed

2) ab initio implausibility – in which later evidence may only be disregarded if there are reasons for the skilled person to doubt that the technical effect had been achieved at the filing date

3) no plausibility – in which there is no requirement for plausibility at the filing date.

The Board has thus referred three questions to the Enlarged Board:

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)?

We await the Enlarged Board's decision with interest, as the answers to these questions are likely to have significant impact on the requirements for drafting strong patents, particularly in the life sciences and pharmaceuticals sectors.