b) Decisions prior to G 2/21 

In the following decisions, which were all made before the decision in G 2/21 (OJ 2023, A85) and comprise also (in large part) those which were analysed in that decision by the Enlarged Board, reference is still made to the notions of plausibility and implausibility, concepts the Enlarged Board G 2/21 found to have no legal basis under the EPC (see point 92 of the Reasons). However, as noted above in chapter I.D.4.3.3a), the Enlarged Board emphasised that it understood from this case law as common ground that the core issue rested with the question of what the skilled person, with the common general knowledge in mind, understood at the filing date from the application as originally filed as the technical teaching of the claimed invention. Applying this understanding to the analysed decisions, in an attempt to test the Enlarged Board’s understanding, the Enlarged Board was satisfied that the outcome in each particular case would not have been different from the actual finding of the respective board of appeal.

(i) General considerations

In T 1329/04 the board did not take into consideration post-published evidence and ultimately denied an inventive step of the claimed subject-matter because the application as originally filed lacked enough evidence to make it at least plausible that a solution had been found to the purportedly solved problem (that GDF-9 was indeed a growth differentiation factor). Since the post-published evidence was considered to be the first disclosure going beyond speculation, it could not be taken into consideration. The board held that even if supplementary post-published evidence might in the proper circumstances also be taken into consideration, it may not serve as the sole basis to establish that the application indeed solves the problem it purports to solve (see also T 861/08, T 778/08, T 415/11, T 1791/11, T 1285/13 T 488/16, T 1099/16, T 212/17, T 1322/17).

Numerous other decisions have held that post-published evidence could only be used to back up the teaching derivable from the application (see e.g. T 716/08, T 578/06, T 861/08, T 1196/12, T 2315/13, T 377/18).

In T 716/08 the board stated that as to the quality of the evidence in the application, "absolute proof" of the achievement of an effect was not required for the effect to be "plausible". See also T 266/10, in which the board similarly held that whether the effect of proposed modifications could be regarded as plausible did not depend on such absolute proof in the disclosure of the disputed patent that the effect was actually achieved.

In T 578/06 the board stated that the EPC required no experimental proof for patentability and considered that the disclosure of experimental data or results in the application as filed and/or post-published evidence was not always required to establish that the claimed subject-matter solved the objective technical problem. This was in particular true in the absence of any formulated substantiated doubt. The board re-emphasised in this context however that the case law (with specific reference to T 716/08, T 1329/04, T 893/02) considered the establishment of plausibility only relevant when examining inventive step if the case in hand allowed the substantiation of doubts about the suitability of the claimed invention to solve the technical problem addressed and when it was thus far from straightforward that the claimed invention solved the formulated problem. See also T 2197/09.

In T 2371/13, however, the board held that the fact that an effect had to be regarded as implausible because it was not backed up in the application was not a good enough reason to disregard comparative tests filed later with a view to proving it. To do so for that reason would run counter to the problem and solution approach, which required that a technical problem be defined in light of the closest prior art, which was not necessarily that cited in the application. It was common, the board observed, to try to demonstrate inventive step on the basis of a technical effect not explicitly mentioned in the application as filed. The objection that the invention had yet to be achieved when the application was filed was anyway more a matter for consideration under Art. 83 EPC. On "Reformulation of the technical problem", see also chapter I.D.4.4 below.

In T 31/18 the board of appeal held that the technical effect relied upon for inventive step according to the problem-solution approach must either be explicitly mentioned in the application as filed or at least be derivable therefrom (see also chapter I.D.4.1.2), but not necessarily originally supported by experimental evidence.

(ii) Decisions taking into account post-published evidence only if the purported technical effect is "plausible"

– Post-published evidence taken into account

In T 1336/04 the board pointed out that the situation in the case in hand was different from that underlying the decision T 1329/04 as to the quality of evidence provided in the patent in suit relating to the claimed invention being a bona fide solution to the problem to be solved. In the case in hand the subject-matter of claim 1 related to novel cellulose- or hemicellulose-degrading enzymes as characterized by the homology of their CBDs to that of known cellulases. On this basis, the board accepted that the problem was satisfactorily solved, also taking into consideration the disclosure in a post-published document.

In T 108/09, in acknowledging plausibility, the board contrasted the case underlying that decision with that in T 1329/04, in which decision there had been prima facie serious doubts that the subject matter solved the problem of the invention. The patent in suit, however, contained detailed information as to how fulvestrant had to be formulated and administered in order to obtain the desired effect as a third-line agent in the treatment of breast cancer. The post-published evidence was far from being the only source of information regarding the question whether fulvestrant was useful as a third-line agent, so that the data contained therein may be used in the evaluation of whether or not the problem underlying the present invention has been plausibly solved.

Some further examples of cases, in which the board took into account the submitted post-published evidence, are: T 433/05, T 294/07, T 2134/10, T 872/13, T 1898/15, T 212/17.

– Post-published evidence not taken into account

In T 1791/11 the board stated it was apparent from the patent application itself that it was not yet known which variants solved the problem and that a test still had to be performed to confirm the alleged advantage. The board thus came to the conclusion that the patent did not render it plausible that the claimed subject-matter solved the technical problem as formulated by the appellant-proprietor, and the experimental post-published evidence was in fact the sole basis allowing to conclude that said problem has been plausibly solved.

In T 787/14 the board held that the verification of whether or not the claimed solution actually solved the problem, i.e. whether the claimed subject-matter actually provided the desired effect, had to be based on the data in the application in order to avoid that an invention is based on knowledge available after the effective date only. Post-published evidence to support that the claimed subject-matter solved the underlying technical problem could only be taken into account if it was already credible from the disclosure in the patent that the problem was indeed solved. See also T 1442/18.

In T 488/16 the board stated that the question of whether an invention was plausible could not be answered in general, as this assessment depended upon the individual circumstances, namely the nature of the invention, the disclosure of the specification and common general knowledge. In the case in hand the board found that the post-published documents were the first disclosure showing that at least for certain thiazole, in particular dasatinib, the purported technical problem had actually been solved. In accordance with established case law, these documents were therefore not taken into consideration in the assessment of inventive step.

In T 1322/17 the board noted that experimental evidence was not always necessary to render a certain effect plausible. A mechanistic explanation and/or common general knowledge could be sufficient in certain instances. However, results only known to the inventors derived from studies of unknown set-up (e.g. dosage regimen) could not be considered when assessing the plausibility of certain effects. A mere statement that a certain effect arises (under conditions that were not reflected by the technical features of the claim), in the absence of any supporting circumstances, did not render the achievement of the effect plausible. The board found in the case in hand that since a technical effect related to higher fracture reduction had not been made plausible for the specific dose of 150 mg ibandronic acid administered in any dosing interval in the application as filed, the post-published evidence could not be taken into consideration.

In T 235/13 the board found that post-published evidence could not be taken into account as evidence for a further, previously undisclosed, effect, such as a hitherto unknown specific advantage for which there was no suggestion at all in the application as filed. The present application failed to indicate, in either the disclosure of the invention or the discussion of the prior art, any improvement to a therapy, let alone improved bioavailability of the therapeutic compound. Hence, the further effect changed the character of the invention and for this very reason could not be taken into account.

In T 377/18 the board held that in the absence of any indication in the application as filed that regorafenib could be used upon failure of treatment with other actives of the same chemical class, i.e. diaryl ureas discussed in the background section with reference to document (5), the post-published evidence showing that "regorafenib was even effective in patients who showed insufficient response to the treatment with sorafenib" could not be taken into account for assessing inventive step.

Some further examples of cases, in which the board did not consider the submitted post-published evidence, are: T 1306/04, T 125/12, T 1433/14, T 1099/16.

(iii) Decisions taking into account post-published evidence on the basis the purported technical effect is not "implausible"

In T 1642/07 the board observed that there was no requirement in the EPC, let alone in Art. 56 EPC, that a patent application should include experimental evidence in support of patentability or a claimed technical effect. Hence, the fact that the disclosure in a patent application was merely theoretical and not supported by experimental data was in itself no bar to patentability or to the presence of a technical effect being acknowledged. The board found that the post-published documents could be viewed as being a mere confirmation of the technical effect already announced (albeit at a theoretical level) in the application as filed. It saw no reasons for doubting the described technical effect, and held the post-published evidence could be taken into account.

In T 536/07 the board noted that although there were no working examples for the claimed subject-matter in the contested patent and it was not disclosed as a preferred embodiment, there was a priori no reason for the skilled person to consider it not to be a plausible solution to the technical problem. There was no indication of a possible prejudice in the art or of foreseen difficulties in carrying out the proposed solution. The board in the case in hand took into account the post-published evidence on file demonstrating the feasibility of the proposed solution.

In T 1677/11 the board noted the facts of the present case differed substantially from those underlying decision T 1329/04. In the case in hand the structure of the claimed sodium salt of (-)-omeprazole was fully consistent with that of the known class of gastric acid secretion inhibitors, whereas in T 1329/04 the structural features of the polypeptide were found to be inconsistent with that expected of the superfamily. Moreover, the patent in suit disclosed a synthesis of the claimed salt and provided a clear statement that it provided "an improved therapeutic profile such as a lower degree of interindividual variation". The board thus saw no reason a priori for the skilled person to regard it as being implausible and considered it appropriate to take into account the post-published evidence submitted for the purpose of assessing whether or not the effect identified was indeed observed.

In T 919/15 the board found that, in the absence of any indications to the contrary in common general knowledge, a synergy between the herbicide combinations containing herbicide (A) which had not been tested in the application as filed could not be regarded as implausible per se. This finding was line with the decision in T 863/12, in which one of the reasons for considering an effect plausible had been that there was nothing in common general knowledge to cast doubt on its plausibility. See also T 2097/15.

In T 184/16 the application as filed did not contain any experimental evidence as regards the plausibility of the claimed compounds being SGLT2 inhibitors. It was thus necessary to determine whether plausibility could nevertheless be acknowledged in view of the common general knowledge and the prior art. The board had no indication that there was prima facie any serious doubt that the claimed therapeutic effect could be obtained, nor had the appellant (opponent) argued that there existed any. Furthermore, there was no a priori reason or any indication in the common general knowledge that the claimed therapeutic effect could not be obtained. In view of the above, the board considered it plausible that the therapeutic effect defined in claim 12 was indeed obtained and the board found post-published evidence D4 could be taken into consideration to support the disclosure in the patent application.

In T 2015/20 the board held that the approaches developed in the jurisprudence of the Boards of Appeal of the EPO for the assessment of sufficiency of disclosure and inventive step specifically took account of the technical contribution actually disclosed in a patent application to avoid patent protection resulting from unreasonable speculation on the basis of propositions that are prima facie implausible. In the case in hand the board considered the statement in the application, that the treatment of respiratory disorders, particularly asthma and COPD, with aclidinium was most effective upon administration by inhalation in a dosage of about 400 myg metered nominal dose to represent a significant technical teaching, which was far from an invitation to perform a research programme and which did not prima facie lack plausibility.