The evaluation of the inventive step of claimed subject-matter at the EPO is based on an approach which usually requires proof of an advantageous technical effect for said subject-matter, e.g. based on evidence such like comparative experimental data showing said advantage relative to what the EPO considers to be the closest prior art to the claimed subject-matter.

Since the applicant is often unaware of the prior art considered by the EPO to be the closest, the originally filed application does not usually comprise such evidence as comparative experimental data. The solution to this problem is to file said required evidence later and to rely on such “post-published” evidence to demonstrate the advantageous technical effect in support of inventive step.

A question of fundamental importance is to what extent and under what circumstances the applicant should be allowed to rely on such post-published evidence, in particular when the technical effect in question rests exclusively on said post-published evidence.

In the recent decision G 2/21, the EPO’s Enlarged Boards of Appeal (EBoA) held that said questions should be seen in the context of the EPO’s principle of free evaluation of evidence not allowing to disregard post-published evidence for the sole reason that is was submitted after the application’s filing date. In the EBoA’ words as per the first headnote of said decision:

Evidence submitted by a patent applicant or proprietor to prove a technical effect relied upon for acknowledgment 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.

Apart from the fact that the EBoA thereby confirms that post-published evidence can still be submitted to support an inventive step, the EBoA also provides some highly abstract guidance as to considerations which should help to take a decision 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 as per the second headnote of said decision (underlining added):

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 filed, would derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention.

In order to put said EBoA’s abstract guidance into practice, it would be helpful to understand what it means for an effect to be “encompassed by the technical teaching” and “embodied by the same invention”. Unfortunately, said decision does not provide the desired clarity in this regard, which may lead to different views of its interpretation.

However, what the decision points out clearly in the “intermediate conclusion” section in paragraph 77 on page 66 of the decision is that in the case of medical use claims,

… 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, if 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.

In an exemplary scenario, this therefore means the following:

If, for example, a compound achieves a therapeutic effect that is completely unexpected and, for example, contradicts a prejudice among experts, but the corresponding experimental data are missing from the originally filed patent application (e.g. because the application had to be filed as quickly as possible and the experimental results were initially only preliminary results that were found not to be good enough for the application and were therefore not included in the application), this can no longer be rectified by the subsequent filing of such experimental data for arguing inventive step based on said post-published data.