In October 2021, EPO Board of Appeal 3.3.02 (also called “the referring board” within this article) has issued an interlocutory decision on a long-awaited referral to the Enlarged Board of Appeal with respect to plausibility and post-published evidence (case number T 116/18, also called “the referral” throughout this article).
In essence, the referral is concerned with the question, if post-published evidence must be considered or disregarded, if the proof of the technical effect rests exclusively on the post-published evidence.
This question seems to be primarily important at least for the fields of chemistry, pharmacy and biology/biotech. In these technical fields, experiments are often included in the description as filed in order to demonstrate a technical effect over a certain prior art, which is usually deemed as the closest prior art at the time of filing. Sometimes experimental data is only fully available after the patent application has been filed. During examination proceedings or opposition proceedings, it often turns out that the closest prior art document is different from the document which was considered as the closest prior art by the applicant at the time of filing. Therefore, experiments for demonstrating a technical are often not present in the application as filed in comparison with such “new closest prior art document”. Therefore, the applicant/patentee often has to rely on post-published evidence (i.e. experimental data) for demonstrating a technical effect over this new closest prior document in accordance with the problem-and-solution approach for proofing an inventive step. Due to diverging case law of the Boards of Appeal, three diverging lines, as defined by the referring board, have been developed on the question, if such post-published evidence can or cannot be considered.
The referring board denotes the first line of this case law “ab initio plausibility”. This means that an achievement of the purported technical effect needs to be at least rendered plausible to the skilled person by experimental data filed with the original application and/or by common general knowledge at the filing date. If this prerequisite is fulfilled, post-published evidence can be taken into account. Typically, experiments or theoretical scientific explanations can be supportive reasons for assuming “ab initio plausibility”. Various decisions (T 415/11, T 488/16, T 609/02, T 895/13, T 1329/04, and T 1791/11) supporting the “ab initio plausibility” approach are cited by the referring board. The “ab initio plausibility” approach shall “ensure that the patent applicant was actually in possession of the invention at the time of filing to prevent purely speculative claiming and thus to safeguard a balance between the actual technical contribution and the patent monopoly defined by the claims” (see point 13.4.1 of the reasons in the referral).
A different and second line of case law is the so-called “ab initio implausibility” (see point 13.5 of the reasons of the referral). Accordingly, post-published evidence can only be disregarded, if there are substantiated doubts that the alleged technical effect would have been actually achieved on the filing date. Substantiated doubts can arise from the application as filed or from the common general knowledge at the filing date. In other words, post-published evidence must always be taken into account, unless the purported technical effect is implausible at the filing date. Therefore, while ab initio plausibility is rather opponent-friendly, ab initio implausibility seems to be rather in favor of applicants/patentees. “Ab initio implausibility” has also been applied within the reasoning of various decisions by the Boards of Appeal (T 266/10, T 536/07, T 863/12, T 919/15 and 1437/07) cited by the referring board. One important reason supporting this line of case law is that the EPC does not require experimental proof for patentability (see point 13.5.2 of the referral).
The third line of case law is simply called “no plausibility” (see point 13.6 of the reasons of the referral). According to this line of case law, any experimental evidence filed anytime after the filing date of the patent application can be taken into account. There are at least two decisions by the Boards of Appeal holding this “no plausibility” position (see T 31/18 and T 2371/13), which are explicitly mentioned by the referring board. The main rationale behind the “no plausibility position” seems to be that “plausibility” is not in accordance with the problem-and-solution approach, because the closest prior art document can change during the proceedings and it can “indeed not be expected from a patent applicant to include an extensive number of experimental evidences corresponding to all technical features which can possibly be claimed in the application as filed and which can possibly constitute a future distinguishing feature over the closest prior art, since said closest prior art and its technical disclosure may not be known to the applicant at the filing date of the application” (see point 2.5.2 of the reasons of T 31/18; also cited under point 13.6.1 of the reasons of the referral).
There are three referral questions resulting from these three diverging lines of case law aiming at a decision of the Enlarged Board of Appeal which line of case law shall prevail. Depending on the Enlarged Board of Appeal’s position, there might also be hybrid cases between these three lines of case law mentioned above.
Although the referral case is concerned with the question, if post-published evidence may be considered during the inventive step assessment, the referral questions do not explicitly mention the term “inventive step”. This is because post-published evidence and plausibility can also be decisive in the assessment under Article 83 EPC (sufficiency of disclosure). Some of the case law cited above is also concerned with the admissibility of post-published under Article 83 EPC. Plausibility is assessed under Article 56 EPC i.e. inventive step, if the effect in question is part of the technical problem to be solved, whereas plausibility is treated under Article 83 EPC, i.e. sufficiency of disclosure, if the effect in question is expressed in the claims (see e.g. point 13.3.1 of the reasons of the referral; and G 1/03 (OJ EPO 2004, 413), point 2.5.2 of the Reasons). The latter case can for example be a second medical use claim or a Swiss-type claim.
The case will be handled at the Enlarged Board of Appeal under the case number G 2/21. If the line of ab initio plausibility is established, a patentee can easily lose his patent during an opposition, if a new closest prior art document appears during the proceedings, because no post-published evidence can be filed anymore in order to demonstrate a technical effect over such closest prior art document. This would turn “plausibility” into a ground for revocation. Another consequence could be that a priority document cannot be considered to include an enabling disclosure, if it does not include experimental data, which can often be the case. Thus, a priority claim could be easily lost.
Therefore, the answer(s) to the referral might even have a crucial impact on applicants’ behavior and decisions to use the EP application route in the future or to prefer filing several national patent applications instead – at least in the field of chemistry, pharmacy and biology/biotech.
Independently of the outcome of the case, the referral seems to be overdue because of the diverging case law on the important question, if post-published evidence can be used to support a technical effect.
The importance of the referral is furthermore underlined by the decision of the President of the EPO that all examination and opposition proceedings in which the decision depends entirely on the outcome of the referral will be stayed ex officio (see Official Journal EPO, 2021, A87).
