As we previously reported here, in 2021 the Enlarged Board of Appeal (EBA) of the European Patent Office was asked to decide upon certain questions regarding the subject of the "plausibility" of an invention as disclosed in the specification as filed, and in particular whether post-filed data can be used to support a purported technical effect. 

To refresh everyone's memories, the patent in question (EP patent number 2484209) relates to an insecticide comprising two selected ingredients, between which a synergistic effect is alleged to constitute the technical effect of the invention. During the appeal proceedings the patentee provided post-published documents as evidence of the synergistic effect; however, the opponent argued that this synergistic effect had not been made plausible in the application as filed, and that the post-published documents should thus not be taken into account. The admissibility of the post-published documents is critical to the issue of inventive step, and thus the validity of the patent, and the EBA was asked to decide upon the following questions:

1. Should post-filed data be disregarded if these data are the sole evidence for a technical effect?
2. If yes to (1), can post-filed data be taken into account if there is ab initio plausibility? 
3. If yes to (1), can post-filed data be taken into account if there is ab initio implausibility?

("Ab initio" plausibility means that a patent application as filed must make it at least plausible that the problem purported to be addressed by the invention has been solved).

The EBA has now released its written decision, and, in some might say typical EBA fashion, has seemingly contrived to avoid the knotty problem of "plausibility" at all as a legal concept.

Thus, according to the EBA the correct test is what a skilled person, in view of common general knowledge, would understand from the application as filed, and for inventive step whether the purported technical effect is "encompassed by the teaching" of the application as filed. In answering the question about post-published evidence to support a technical effect, the EBA thus concluded: 

"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."

No doubt, like me, you're wondering what  "encompassed by the technical teaching" and "embodied by the same invention" actually mean, terms which are clearly open to interpretation. For example, are the EBA giving the green light to an inventive step based on a technical effect that is not explicitly described in the application as filed, but with the caveat that a skilled person must be free from doubt in view of the application as filed that the invention as claimed has the purported effect? It appears that the Technical Boards of Appeal will have a certain amount of discretion as to what post-filed evidence they will allow in particular cases. And it may result in more emphasis/importance being placed upon identification and disclosure of the technical effect from the specification as filed.

And what happened to "plausibility"? Essentially, dismissed as not being useful to the legal question at issue, a term that "does not amount to a distinctive legal concept or a specific patent law requirement under the EPC".  As noted here, plausibility has never been a ground of revocation or a requirement for patentabillity under European patent law. So, perhaps the EBA is just confirming what we already knew.