Enlarged board of appeal’s decision on the "plausibility" referral

On March 23rd, 2023 the Enlarged Board of Appeal (EBA) of the EPO (EPO) has issued its decision in the “plausibility” referral.

The questions referred to the EBA sought guidance on the issue of whether post-published evidence (evidence published after the filing date of the application or patent) could always be relied on to prove a purported technical effect underlying the inventive step of an invention, or only when the technical effect would have been plausible or at least not implausible from the viewpoint of the skilled person based on information already contained in the application as filed (see our earlier post on this matter).

The EBA decision first underscores the crucial importance of the principle of free evaluation of evidence for the parties’ right to be heard before the EPO:

“Evidence submitted by a patent applicant or proprietor to prove a technical effect relied upon for acknowledgement of 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.”

As regards the different approaches to “plausibility” taken in earlier decisions by the EPO Boards of Appeal and national courts, the EBA searched for the common ground and proposes 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. Accordingly, the EBA answers:

“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,” (emphasis added).

While the EBA acknowledges the “abstractness of some of the aforementioned criteria”, it believes that the guiding principles provided by this decision will allow the competent Boards or other deciding bodies of the EPO to take a decision, considering the circumstances of each specific case, 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.

It remains to be seen whether determining whether the technical effect is "encompassed by the technical teaching and embodied by the same originally disclosed invention" will be less controversial than the "(im)plausibility" standard referred to by the EPO in the previous case law. In this respect, the EBA found the outcomes of the analysis under the new approach consistent with the outcomes of the earlier Board decisions relying on the “plausibility” approaches, and hence the previous case law continues to hold useful lessons which applicants can rely on.

Importantly, while the Board was not asked to and did not consider it necessary to deal with the issue of post-published evidence under the ground of sufficiency of disclosure, it did provide some comparative considerations in this regard, in particular concerning second medical use claims, and observed:

“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,” (emphasis added).

Accordingly, applicants may prefer to continue the current cautious practice to include in their medical field applications experimental tests showing at least that the claimed compound has a direct effect on a metabolic mechanism specifically involved in the disease, which mechanism may be known either from the prior art or demonstrated in the patent application.

We will carefully monitor how the EPO deciding bodies and eventually the Boards apply this guidance, and whether their future decisions will indeed tie together the various “plausibility” approaches used today or rather create new divergences in the case law, which might then possibly necessitate a new referral to the EBA.

For more information, please contact our Patent Attorneys at De Clercq & partners at info@dcp-ip.com.