Inventive step and thus patentability of the claimed invention may be based on experimental data demonstrating a technical effect. In interim decision EPO T 116/18 - "Insecticide compositions" of October 11, 2021, questions on the admissibility of taking into account experimental data filed after the filing date of the patent application were referred to the Enlarged Board of Appeal (reference G 2/21).
Background - assessment of inventive step at the EPO
Presence of an inventive step is a prerequisite for the grant and validity of a European patent. For the assessment of inventive step, the so-called problem-solution approach is applied in the proceedings before the European Patent Office. According to the Guidelines for the Examination of the European Patent Office (hereinafter referred to as "Guidelines"), the problem-solution approach is intended to make the assessment of inventive step objective and predictable. Under the problem-solution approach, experimental data showing that the distinguishing feature(s) imparts (or impart) a technical effect over the closest prior art may lead to the formulation of a challenging objective technical problem and subsequently to an affirmative finding of inventive step. However, on the filing date of the patent application the applicant often is not aware of the closest prior art determined in the context of the problem-solution approach. This is particularly the case if the development is based on own products or processes which do not represent the closest prior art. According to the guidelines, in some cases there are also several equivalent starting points (closest prior art) for the assessment of inventive step. Then, when assessing the inventive step, it may be necessary to formulate the problem-solution approach starting from each closest prior art. For these reasons, a patent application often does not contain experimental data showing a technical effect over the closest prior art for the distinguishing feature(s) as determined under the problem-solution approach. For the affirmation of inventive step, it may be decisive that experimental data can be submitted after the filing date of the patent application in order to show a technical effect for the distinguishing feature(s) compared to the closest prior art., . Accordingly, according to the currently applicable guidelines, the relevant information and evidence to be taken into account in the assessment of inventive step may be filed as so-called "post-published evidence" even after the filing date of the patent application. However, according to the guidelines, if new technical effects are mentioned in support of the inventive step, such new technical effects can only be taken into account if they are implicit in, or at least related to, the problem originally posed, as it results from the application as originally filed.
The case at hand
In the present opposition appeal proceedings "Insecticide compositions" (Syngenta versus Sumitomo Chemical Company) before the Board of Appeal 3.3.02 of the European Patent Office, experimental data which were only filed in the opposition proceedings are decisive for the affirmation of inventive step. Considering these experimental data, the objective technical problem can be fastidiously formulated as providing an insecticide composition in which the insecticides have synergistic activity against a particular pest. The solution to the problem would be inventive. Without this experimental data, the objective technical problem can only be formulated in a less demanding way as providing an alternative insecticide composition. The solution to this problem would not be inventive. Thus, the validity of the patent in the present opposition proceedings depends on the consideration of the experimental data. In the present interlocutory decision T 116/18, the Board of Appeal is of the opinion that three different lines of case law have emerged among the Boards of Appeal regarding the circumstances under which so-called "post-published evidence" may or may not be taken into account. The legal question under which circumstances so-called "post-published evidence" may or may not be taken into account is of fundamental importance and a decision essential to ensure a uniform application of the law.
The questions referred
Therefore, the following three questions were referred to the Enlarged Board of Appeal with the present interlocutory decision (reference G 2/21):
"If for acknowledgement of inventive step the patent proprietor relies on a technical effect and has submitted evidence, such as experimental data, to prove such an effect, this evidence not having been public before the filing date of the patent in suit and having been filed after that date (post-published evidence):
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)?"
A strict application of the ab initio plausibility standard would result in obtaining a patent only for those embodiments for which the patent application contains experimental data that makes the technical effect claimed over the closest prior art for the inventive step plausible for those embodiments.If there is no plausibility check to be made at all, a patent applicant could claim with a prospect of success anything that he believes might later prove to be a means of bringing about a claimed technical effect. This could result in a patent applicant being granted an exclusive right of use for mere speculation rather than for a genuine invention. This would not be in the spirit of the patent system, which is intended to grant an exclusive right of use in exchange for disclosure of the invention. The application of the ab initio implausibility standard would lie somewhere between these two extreme lines of case law in terms of its results. A strict application of the ab initio plausibility standard would be problematic if a new or additional document is determined to be the closest prior art under the problem-solution approach. In this case, further experimental data as evidence of a technical effect of the distinguishing feature over the closest prior art and a reformulation of the objective technical problem might be necessary. However, the patent applicant cannot be expected to file experimental data on all conceivable objective technical problems with the patent application.
The referred questions are highly relevant, especially in the field of life sciences, because in these fields a technical effect can often only be derived from experimental data. The consideration of subsequently submitted experimental data to prove a technical effect under the problem-solution approach at the EPO is controversial. At least in the field of life sciences, patent applicants are generally well advised, until the decision of the Enlarged Board of Appeal, to disclose comprehensive experimental data in their patent application to support the inventive step. The answers of the Enlarged Board of Appeal to the questions referred are relevant for the outcome of numerous examination and opposition proceedings. In cases concerned, a suspension of the application or opposition proceedings may be considered.
 Guidelines for the Examination of the European Patent Office dated March 2021, Part G, Chapter VII, 5.
 Guidelines for Examination of the European Patent Office dated March 2021, Part G, Chapter VII, 5.1.
 EPA T 116/18 of 11.10.2021 - Insecticide compositions (reasons for decision 14.).
 Guidelines for Examination of the European Patent Office dated March 2021, Part G, Chapter VII, 11.
 EPA T 116/18 of 11.10.2021 - Insecticide compositions (reasons for decision 13.2, 14.).
 EPA T 116/18 of 11.10.2021 - Insecticide compositions (reasons for decision 13.7.1).