EPO’s highest court holds G2/21 (“Plausibility”) hearing
The Enlarged Board of Appeal (EBA) has held an important hearing relating to when data can be filed to support inventive step.

Today, the Enlarged Board of Appeal (EBA) held the important G2/21 (“Plausibility”) hearing. G2/21 seeks to clarify whether a technical effect can be relied on when proof for the effect rests solely in post‑published evidence and what role, if any, plausibility should play in this assessment. The Board issued a preliminary opinion in advance of the hearing (see our previous note), which gave an insight into how it might rule on this matter. At today’s hearing, the Board raised several discussion points that give a flavour of the factors that it considers to be important for its deliberations.

The EBA referral arose from appeal proceedings relating to European Patent No. 2484209 (Sumitomo Chemical Company, Limited), which had been opposed by Syngenta Limited. Sumitomo and Syngenta presented arguments and answered questions from the Board at the hearing. Representatives for the EPO President also contributed. The EBA did not pronounce a decision at the hearing. It intends to issue a written decision as soon as possible.

The parties’ submissions

The Board opened the hearing by summarising its preliminary opinion. The parties then took the floor. Sumitomo argued first that there should be no plausibility requirement in the assessment of inventive step. It then suggested that if there was to be a plausibility requirement in this context, then the threshold should be as low as possible. In doing so, it proposed that of the two standards set out in the referred questions, ab initio implausibility was more appropriate. In contrast, Syngenta maintained its position that the standard to be applied is ab initio plausibility. The EPO President’s position appeared to be less clear. The EPO’s President’s representatives argued that a technical effect should be at least plausible on the basis of the application as filed (taking into account the common general knowledge), which seems to be an endorsement of the ab initio plausibility standard. This approach was said to ensure that the technical contribution is commensurate with the exclusivity awarded. There was also an indication that the existence of significant doubts regarding the achievement of the technical effect at the filing date may also be a relevant factor in determining whether post-published data may be relied upon. It was also confirmed that the EPO President agreed with the possibility of reformulation of an objective technical problem based on new prior art under certain circumstances.

Sumitomo and Syngenta discussed the similarities and differences between plausibility under Article 83 EPC (sufficiency of disclosure) and Article 56 EPC (inventive step). Sumitomo’s view appeared to be that the standard should be different under these grounds (specifically, no plausibility or ab initio implausibility under Article 56 EPC and ab initio plausibility under Article 83 EPC). In contrast, Syngenta asserted that the same ab initio plausibility standard must be applied for both grounds.

The parties also discussed whether an effect needs to be plausible over the whole scope of a claim. Sumitomo’s position was that any issue relating to the scope of a claim was separate from plausibility, whereas Syngenta’s position was that the two are intertwined, i.e. an effect must be plausible across the whole scope of a claim.

Finally, the parties supported their positions with references to policy considerations. Sumitomo argued that a low bar should be set for plausibility because an applicant could not be expected to anticipate all experiments that might be necessary to prove a technical effect over a document that it was unaware of at the filing date. Sumitomo also asserted that the EPO’s first-to-file system encourages early filing, and it is often not possible to delay filing an application until all potentially useful experiments have been conducted. For its part, Syngenta highlighted that third parties need certainty as to what may be granted by the EPO and upheld post-grant, which would not be possible if applicants/proprietors were able to rely on new technical effects many years after the filing date.

The Board’s questions

After the parties had made their primary submissions, there were a series of questions from the Board, leading to further discussion among the parties. The questions covered various themes, including:

  • whether post‑published data can be used to show the objective effect of an invention in response to a new piece of prior art, and what the legal and practical consequences of this might be;
  • the differences between an inventor’s perspective of their invention before the filing of a patent application and the assessment of that invention in light of the prior art; and
  • the impact of a plausibility requirement in different technical areas (specifically mechanical versus chemical inventions).

The Board also sought clarification of the parties’ position on various points (e.g. Sumitomo’s position that there should be a different standard applied to inventive step and sufficiency, and Syngenta’s definition of the ab initio implausibility standard).

It is difficult to draw conclusions from the Board’s line of questioning, although the setting of the questions and the parties to whom they were directed (primarily, the opponent), suggests that the Board was looking to flush out any reasons to change the views expressed in their preliminary opinion.

Final remarks

The Board indicated that it is fully aware of the profound significance of these proceedings to the patent world. As a result, it will be prioritizing the publication of a reasoned decision. This might mean that the decision is issued sooner than had been expected, perhaps as early as Q1 2023. We will continue to monitor the referral and will provide an update once the decision has been issued.