T 0116/18 - (II) Referral G2/21 - Plausibility

 Key points

• As abundantly reported elsewhere, Technical Board 3.3.02 referred questions to the Enlarged Board about ‘plausibility’.
• The file wrapper is here.
• The TBA has carefully formulated questions, but let's approach the referral from a different angle in this blog post. The topic of ‘plausibility’ lends itself to a broad enquiry, but there is a point to resolve on a quite narrow issue where there is a divergence in the case law. 
• Perhaps at the outset, it must be noted that ‘plausibility’ is not a term used in the EPC and the mechanical Boards typically don't ‘do’ plausibility. Nevertheless, the issue of plausibility is by no means a priori restricted to the chemistry/pharma/biotech field. 
• The narrow issue is, as summarized by Arnie Clarke (link): “As much as Dasatinib [ (T 488/16 of Board 3.3.01] raised the plausibility threshold, Almirall [T 2015/20 ; Board 3.3.07] appears not just to return the bar to its previous position but significantly lowers it, if not quite removing it completely. As much as the pharmaceutical industry should be pleased to see a relaxation of the Dasatinib [T 488/16] standard, the volte face by this EPO board of appeal could be a significant impediment to industry, with “not implausible” armchair inventions blocking legitimate innovation and development. Will other boards follow [T2015/20/ Almirall]?”
• The present Board 3.3.02 identifies a third option, namely: "no plausibility requirement at all" based on T 0031/18 (Novartis; Board 3.3.07) and T 2371/13 (Board 3.3.10) (the latter decision taken before the written decision in T 488/16 was available).
• Plausibility, in this context, means the (supposed) rule that post-published documents can only be considered as evidence for a technical effect in the assessment of inventive step, if that technical effect is at least made plausible by the application as filed.
• The three referred questions basically present three options: 1 - Novartis (no plausibility requirement); 2 - Dasatinib (plausibility requirement) and 3 - Almirall (soft plausibility requirement of "not implausible"), in this order.
• The actually important difference between options 2 and 3 is that “under the ab initio plausibility line [i.e. question 2], it is the patent proprietor that has to prove plausibility while in the ab initio implausibility line [i.e. question 3] it is the opponent that has to show implausibility.”
• The referring Board also discusses the UK Supreme Court decision of 14.11.2018  Mylan v Warner-Lambert [2018] UKSC 56, and three articles in the literature: 
• C. Floyd, "Plausibility: where from and where to", GRUR, 2021, page 185 (Festschrift for Peter Meier-Beck - GRUR 2/2021), 
• R. Jacob, "Plausibility and Policy", Bio-Science Law Review 17(6), page 223, and 
• A.Slade, "Plausibility: a conditio sine qua non of patent law?", (2020) Intellectual Property Law Quarterly 180-203; open access copy as SSRN, also available via hdl.handle.net/2381/12410771.v1, 
• As a comment, I'm not sure why only English authors are cited by the referring Board. E.g.  Kutik and Renken in epi Information 2019/3 also discuss the topic (link). Other national courts have also discussed plausibility in the past (e.g. French Supreme Court,  6 December 2017, No. 15-19726 ; ECLI:FR:CCASS:2017:CO01514 ; link; (MSD/Teva)).
• A lot more can be said about the topic but of course the amicus curiae briefs will be available on the EPO website in due course.
• I recommend reading the entire decision (relevant part for the referral) either on the EPO website or below and as of yet refrain from making a bullet point summary of the Board's reasons.

Referred questions

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)?

T 0116/18 -

https://www.epo.org/law-practice/case-law-appeals/recent/t180116ex1.html

11. Referral - Introduction

11.1 After acknowledgement of sufficiency of disclosure and novelty, the next point to be assessed was inventive step. During this assessment, it turned out that questions needed to be referred to the Enlarged Board of Appeal on whether evidence not public before the filing date of the patent in suit and filed after that date ("post-published evidence") can be taken into consideration in view of the plausibility case law of the boards.

11.2 For a referral to be admissible, it is generally considered necessary that the decision on the referral questions be decisive for the outcome of the referral case.

As is clear from the above, the appellant's objections as regards sufficiency and novelty were not successful. Whether an inventive step can be acknowledged will therefore be decisive for the outcome of this case.

For inventive step, the respondent relied on, inter alia, post-published evidence D21 in support of a synergistic effect. In view of the parties' different positions on the applicability of the plausibility case law, both formulated opposing requests as to whether post-published evidence D21 should be taken into consideration.

11.3 The board assessed whether D21 is relevant for inventive step because only if it is does the answer to whether post-published evidence such as D21 can be taken into consideration matters for inventive step and thus the outcome of the case.

The board notes that the appellant also relied on post-published evidence for inventive step, namely D23. After the board had decided to admit D23 on procedural grounds (see above), the respondent did not question that D23 could be taken into account. D23 was therefore taken into consideration in the board's assessment of inventive step. However, the board is aware and pointed out during the oral proceedings that D23 is post-published evidence and that it cannot be excluded that after the decision of the Enlarged Board of Appeal, the question of whether D23 can be taken into consideration might have to be re-assessed.

12. Relevance of post-published evidence D21 for inventive step

12.1 As set out above, it was examined whether post-published evidence D21 is relevant for inventive step. The board therefore used the problem-solution approach without (point 12.4) and with D21 (point 12.5) to answer this question.

12.2 Both parties agreed that D4 was the closest prior art. The board saw no reason to deviate from this unanimous view.

12.3 Based on the assessment above with respect to novelty over D4 and in line with the decision under appeal, the subject-matter of claim 1 of the patent in suit is distinguished over D4 in that both thiamethoxam and the compounds according to formula Ia have to be selected from the respective broader teachings of D4.

12.4 Problem-solution approach without D21

With regard to a technical effect linked to the distinguishing features, the respondent relied on a synergistic effect resulting from the claimed combination of compounds and referred to test examples 2 and 5 of the patent in suit.

12.4.1 Test examples 2 and 5 of the patent in suit are the only examples in which insecticide compositions according to claim 1 are tested against different insect species. Test example 2 shows that the combination of thiamethoxam with compound I-1 (in formula Ia: R**(1) = CF3, R**(2) = Cl, R**(3) = Me, R**(4) = H, R**(5) = i-Pr) acts synergistically against Spodoptera litura when both insecticides are used at a weight ratio of 1:1. Similarly, test example 5 shows that the combination of thiamethoxam with compound I-4 (in formula Ia: R**(1) = Cl, R**(2) = Cl, R**(3) = Me, R**(4) = Cl, R**(5) = i-Pr) acts synergistically against Plutella xylostella when both insecticides are used at a weight ratio of 1:1.

12.4.2 Thus, the question to be answered is whether test examples 2 and 5 of the patent in suit provide a valid proof that the claimed subject-matter results in a synergistic effect at least against Spodoptera litura and Plutella xylostella. If this is the case, the objective technical problem could be formulated as the provision of an insecticide composition which acts synergistically against Spodoptera litura and Plutella xylostella.

12.4.3 The appellant did not challenge these results of the patent in suit. However, it referred to its tests described in D23. As stated above, D23 serves to show that the combination of thiamethoxam and chlorantraniliprole, i.e. a compound which falls under formula Ia of claim 1 but which is different from those used in test examples 2 and 5, does not act synergistically against Spodoptera littoralis and Plutella xylostella at certain weight ratios.

12.4.4 The respondent argued that in view of the differences between D23 and the test examples of the patent in suit, the results in D23 had no bearing on the relevance of these test examples. The board does not agree with this argument.

The two relevant examples of D23 are examples 5 and 6. The species used in example 6 of D23 (Plutella xylostella) is the same as that used in test example 5 of the patent in suit. The species used in example 5 of D23 (Spodoptera littoralis) is different from test example 2 of the patent in suit (Spodoptera litura). However, the appellant stated that Spodoptera littoralis was closely related to Spodoptera litura and that therefore the same results had to be expected when the insecticide combinations of example 5 of D23 were used against Spodoptera litura. This was not disputed by the respondent, and the board sees no reason to doubt the appellant's statement.

Furthermore, as argued by the appellant, the general procedure used in D23 was essentially analogous to that described in the patent in suit. The insects were exposed to plant parts treated with an insecticide or a combination of insecticides. After a certain exposure time, the activity of the insecticide(s) (i.e. the death rate) was determined.

This procedure had to be modified in the experiments with Spodoptera littoralis in that further untreated plant parts were added after the treated plant parts had been completely consumed by the insects. However, this only served to prevent the premature death of the insects through starvation and thus a falsification of the results, which otherwise would have been due not only to the insecticides but also to a lack of food.

Lastly, in the test compositions of D23, the appellant used a spreading agent different from the ones used in test examples 2 and 5 of the patent in suit. However, the composition of claim 1 is not limited in this respect and essentially allows any spreading agent to be contained in it.

Contrary to the respondent's arguments, the appellant's modifications of the method of the patent in suit cannot therefore call into question the validity of the experiments in D23.

12.4.5 In D23, dose-response experiments were first carried out to determine suitable concentration ranges of thiamethoxam and chlorantraniliprole for the actual synergy experiments. As set out above, the actual synergy experiments are described in examples 5 and 6 of D23. In these synergy experiments, the activities of the two insecticides thiamethoxam and chlorantraniliprole were initially determined individually again. It may be that, as argued by the respondent, some of the individual activities determined for thiamethoxam or chlorantraniliprole in the dose-response experiments are different from those determined in examples 5 and 6. However, in the board's view, this cannot call into question the validity of the results described in examples 5 and 6 since (i) experiments with living organisms are naturally subject to fluctuations and deviations between different series of experiments are therefore not unusual and (ii) the activities described for the individual insecticides in examples 5 and 6 follow a clear trend, namely towards lower activity with a decreasing amount of insecticide. Because the respondent's defence relating to this alleged lack of reliability was not convincing, there was no need at the oral proceedings to decide on the appellant's request that it not be admitted into the proceedings. In summary, the board considers the results described in examples 5 and 6 of D23 valid.

12.4.6 In example 5 of D23, the effect of the combination of thiamethoxam and chlorantraniliprole against Spodoptera littoralis was determined at 25 different weight ratios in a range from 3840:1 to 15:1 (thiamethoxam:chlor-antraniliprole). In example 6, the effect of the same combination was determined against Plutella xylostella, at 25 different weight ratios, in a range from 16000:1 to 62.5:1.

As can be seen from the tables in examples 5 and 6 of D23, in both cases thiamethoxam and chlorantraniliprole do not act synergistically at all weight ratios, on the contrary, they even clearly act antagonistically at some weight ratios. For example, while the expected death rate in experiment 6 at a weight ratio of 100:0.0125 (thiamethoxam:chlor-antraniliprole) was 62%, the observed death rate was only 14%. For the two specific species, it is not possible to make out a clear tendency towards synergy over the tested range of weight ratios.

Since claim 1 is not limited to compounds I-1 and I-4 used in test examples 2 and 5 and/or their weight ratios to thiamethoxam, the combinations of insecticides with their weight ratios tested in D23 also fall within the subject matter of claim 1. Therefore, it can be concluded that the synergistic effect described in the patent in suit for Plutella xylostella and Spodoptera litura is not achieved over the entire breadth of claim 1.

12.4.7 Thus, given only the experimental data in the patent in suit and in light of D23, the objective technical problem would have to be formulated less ambitiously as the provision of an alternative insecticide composition.

12.4.8 D4 discloses the insecticidal activity of both thiamethoxam and compounds according to formula Ia in claim 1. Moreover, the patent in suit itself acknowledges that their insecticidal activities were known before the priority date of the patent in suit (see above). However, arbitrarily combining compounds known to have insecticidal activity to achieve an alternative insecticide composition does not require an inventive step.

12.4.9 Thus, without D21, i.e. solely in view of the experimental data in the patent in suit and in light of D23, the main request would not be allowable.

12.5 Problem-solution approach with D21

Whether this conclusion changes when D21 is taken into consideration is examined below.

12.5.1 The respondent referred to D21, example 4. This example deals with a different species from that used in test examples 2 and 5 of the patent in suit or in D23. Example 4 shows that thiamethoxam and compound I-1, i.e. a compound according to formula Ia of claim 1, at a weight ratio of 1:8, act synergistically against the insect species Chilo suppressalis. It was a matter of dispute between the parties whether in view of this the objective technical problem could be formulated as the provision of an insecticide composition that acts synergistically against Chilo suppressalis.

The result in example 4 of D21 in itself was not challenged by the appellant, which also did not present any counter-evidence regarding this species in D9, D10 or D23 that could call the result into question.

However, the appellant argued that this isolated example of D21 was not a valid proof of a synergistic effect against Chilo suppressalis for all insecticide compositions covered by claim 1. That was because, according to the appellant's conservative calculations in Annex 1, formula Ia covered over 10 million compounds.

The board does not agree. In view of the data in D21 and in the absence of any counter-evidence from the appellant, the board sees no reason not to acknowledge this synergistic effect against Chilo suppressalis also for other insecticide compositions covered by claim 1, i.e. insecticide compositions comprising thiamethoxam and a compound of formula Ia different from compound I-1.

This position is further supported by the fact that the variability of formula Ia is quite limited in chemical terms. All compounds are based on the same characteristic core structure, namely an anthranilic acid amide part acylated with a (pyridin-2-yl)-1H-pyrazole-5-carboxylic acid. Groups R1 to R5 allow for different substituents, in particular alkyl and haloalkyl groups. According to the appellant's calculations in Annex 1, the number of compounds covered by formula Ia is very high precisely because of these alkyl and haloalkyl groups. However, the compounds of formula Ia and in particular the compounds of formula Ia with different alkyl or haloalkyl groups are, at least in the board's view, not so chemically different that a different behaviour would necessarily be expected in combination with thiamethoxam.

Therefore, the synergistic effect observed in example 4 of D21 against the insect species Chilo suppressalis can be acknowledged to be achieved over the entire breadth of claim 1 provided D21 can be taken into account.

12.5.2 Given the post-published data in D21 and in line with the respondent's arguments, the objective technical problem would have to be formulated as the provision of an insecticide composition in which the insecticides act synergistically against Chilo suppressalis. As explained during the oral proceedings, the board does not take issue with the formulation of this more specific objective technical problem which also includes a specific insect species. This is because it would be technically nonsensical to require synergism against each and every insect species (for a similar view, albeit with regard to sufficiency, see T 1326/08, point 4.2.2 of the Reasons). The respondent did also not object to the formulation of this objective technical problem.

12.5.3 The appellant only ever argued that the objective technical problem lay in providing an alternative insecticide composition. It never addressed obviousness on the basis of the above more ambitious objective technical problem. In fact, the skilled person confronted with the above more ambitious technical problem would not have found any suggestion in the prior art to arrive at the claimed subject-matter. For that reason alone, an inventive step would have to be acknowledged, provided D21 can be taken into account.

12.6 In summary, the main request would not be allowable if only the data in the patent in suit and D23 could be taken into account. If the post-published data in D21 could also be taken into account, the main request would be allowable. Therefore, the allowability of the main request crucially depends on the question of whether the post-published data in D21, which are the only proof of a synergistic effect against Chilo suppressalis, can be taken into account.

13. Need for the referral questions

13.1 As set out below, whether post-published evidence, such as D21, can be taken into account is a fundamental question of law for which diverging lines of case law exist.

13.2 For the assessment of inventive step, the problem-solution approach is regularly applied by the departments of the EPO (Case Law of the Boards of Appeal of the European Patent Office, 9th edition, 2019 (CLBA), I.D.2). This approach requires, inter alia, that:

- the closest prior art be identified (which may not necessarily be the one mentioned in the patent in suit or envisaged by the patent proprietor)

- a comparison be made between the subject-matter of the claim at issue and the disclosure of the closest prior art and that the difference(s) between both be identified

- the technical effect(s), linked to the difference(s), be determined

- the objective technical problem be formulated, i.e. the problem which can be seen to have actually been solved in light of the closest prior art

In this analysis, it is often necessary, like in this case, to provide post-published evidence (i.e. evidence that was not public before the filing date of the patent in suit and was filed after that date) as proof that the problem has been solved (i.e. that the alleged technical effect is actually achieved). This applies in particular when the objective technical problem has to be reformulated, e.g. with regard to a closest prior-art document previously unknown to the patent proprietor.

Where the proof that a problem has been solved (in this case, the provision of an insecticide composition in which the insecticides act synergistically against Chilo suppressalis) rests on such post-published evidence (in this case, D21), there are, in the board's view, three diverging lines of case law from the boards regarding the circumstances under which the evidence can or cannot be taken into account. The subsequent discussion identifies these different lines of case law.

13.3 Before starting this discussion, the board would like to make the following remarks.

13.3.1 Whether D21 can be taken into account arose in the case at hand in the context of inventive step because the synergistic effect is part of the problem to be solved. In other cases, the same issue, namely whether post-published evidence can be taken into account, arose under the heading of sufficiency of disclosure because the effect was expressed in the claim at issue. While the fact that an effect is part of the problem to be solved or expressed in the claim at issue dictates which provision of the EPC is applicable (G 1/03 (OJ EPO 2004, 413), point 2.5.2 of the Reasons), it does not - at least not in the board's view - have an impact on the considerations applying to the above issue. Therefore, not only decisions dealing with this issue under Article(s) 100(a) and/or 56 EPC but also those dealing with this issue under Article(s) 100(b) and/or 83 EPC are mentioned below.

13.3.2 The following discussion is directed at the question of whether post-published evidence can be taken into account on substantive grounds, depending on the plausibility of the technical effect based on the evidence submitted as proof. This discussion should not be confused with whether post-published evidence can be taken into account on procedural grounds in particular in view of Articles 12 and 13 RPBA. The following discussion is based on the assumption that the post-published evidence in question does form part of the appeal proceedings.

13.4 Ab initio plausibility

In accordance with a first line of case law, post-published evidence can be taken into account only if, given the application as filed and the common general knowledge at the filing date, the skilled person would have had reason to assume the purported technical effect to be achieved. In this line of case law, experimental data or a scientific explanation in the application as filed commonly serve as reasons which justify this assumption. This line of case law applies a standard which is referred to in the following as the "ab initio plausibility" standard. The line of case law applying this standard is denoted in the following as the "ab initio plausibility line of case law".

13.4.1 For example, in T 1329/04, the underlying application as filed related to a new polypeptide (denoted growth differentiation factor-9 (GDF-9)), and stated it to be a new member of the transforming growth factor-beta (TGF-beta) superfamily. One alternative in the claim at issue related to GDF-9. In view of the closest prior art, the problem to be solved was defined as isolating a further member of the TGF-beta superfamily. The board in question noted that GDF-9 did not have the structural features generally accepted for members of the TGF-beta superfamily and that the application as filed did not contain any evidence as to whether the mode of action of GDF-9 permitted assignment to the TGF-beta superfamily. Thus, although the application as filed explicitly set out GDF-9 to be a member of the TGF-beta superfamily, the board concluded (point 11 of the Reasons; emphasis added by the current board):

"that the application does not sufficiently identify this factor as a member of this family i.e. that there is not enough evidence in the application to make at least plausible that a solution was found to the problem which was purportedly solved."

Post-published evidence establishing that GDF-9 was indeed a growth differentiation factor was not taken into account, and the presence of an inventive step was ultimately denied. The board based its conclusion on the following consideration, which was later on applied in several other decisions applying the ab initio plausibility standard (point 10 of the Reasons; emphases in bold and annotation in squared brackets by the current board):

"Hence, it is particularly important [in a first-to-file system] that the application allows to conclude that the invention had been made, i.e. that a problem had indeed been solved, not merely put forward at the filing date of the application. Therefore, the issue here is rather how much weight can be given to speculations in the application in the framework of assessing inventive step ..."

Thus, it seems to have been of crucial importance for the board in T 1329/04 (and the other decisions applying the ab initio plausibility standard) to be able to 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.

13.4.2 This decision was in line with the earlier decision

T 609/02, in which the board in the context of sufficiency of disclosure reasoned (points 5 to 9 of the Reasons; emphasis added by the current board) that:

"The patent specification provides no evidence at all relating to the invention in claim 6 ... The appellant provided post-published evidence showing that steroid hormones such as needed to carry out the use according to claim 6 were later structurally identified and that they, indeed, have an effect on AP-1 stimulated transcription. ... On the basis of the disclosures of these post-published documents, it was argued by the appellant that by carrying out the claimed invention, one would necessarily obtain pharmaceutical compositions since it was by following the teachings of the patent in suit that the post-published results had been obtained. Consequently, in the appellant's opinion, sufficiency of disclosure had to be acknowledged. The board cannot share this opinion. Sufficiency of disclosure must be satisfied at the effective date of the patent, ie on the basis of the information in the patent application together with the common general knowledge then available to the skilled person. Acknowledging sufficiency of disclosure on the basis of relevant technical information produced only after this date would lead to granting a patent for a technical teaching which was achieved, and, thus, for an invention which was made, at a date later than the effective date of the patent. The general principle that the extent of monopoly conferred by a patent should correspond to, and be justified by, the technical contribution to the art, has to be kept in mind ... It is required that the patent provides some information in the form of, for example, experimental tests, to the avail that the claimed compound has a direct effect on a metabolic mechanism specifically involved in the disease, this mechanism being either known from the prior art or demonstrated in the patent per se. ... Once this evidence is available from the patent application, then post-published (so-called) expert evidence (if any) may be taken into account, but only to back-up the findings in the patent application in relation to the use of the ingredient as a pharmaceutical, and not to establish sufficiency of disclosure on their own."

13.4.3 The ab initio plausibility standard was adopted for example in T 488/16 that reads (point 4.2, 4.5 and 4.19 of the Reasons; emphases added by the current board):

"It is established jurisprudence of the boards of appeal that the assessment of inventive step is to be made at the effective date of the patent on the basis of the information in the patent together with the common general knowledge then available to the skilled person. Post-published evidence in support that the claimed subject-matter solves the technical problem the patent in suit purports to solve may be taken into consideration, if it is already plausible from the disclosure of the patent that the problem is indeed solved (see Case Law of the Boards of Appeal, 8th edition, I.D.4.6; T 1329/04, point 12 of the Reasons; T 1043/10, point 12 or [sic] the Reasons). Thus, for post-published evidence to be taken into account, it is necessary to establish whether or not the asserted activity has been made sufficiently plausible for dasatinib at the effective date of the patent in suit. Basis for this assessment is the application as filed and the common general knowledge of the person skilled in the art at the filing date."

"In the board's judgement, a mere verbal statement that "compounds have been found active" in the absence of any verifiable technical evidence is not sufficient to render it credible that the technical problem the application purports to solve, namely providing PTK inhibitors to treat disorders or diseases associated therewith, is indeed solved ..."

"... the board concurs with the opposition division and the respondents that the post-published documents (9) and (10) are the first disclosure showing that ... the purported technical problem has actually been solved. In accordance with established case law, these documents are therefore not taken into consideration in the assessment of inventive step."

13.4.4 Other decisions in line with the three mentioned above include T 415/11 (points 45 to 55 of the Reasons), T 1791/11 (points 3.2.5 to 3.2.7 of the Reasons) and T 895/13 (points 15 to 17). In the decisions cited in section 13.4, which all apply the ab initio plausibility standard, plausibility was ultimately denied.

13.5 Ab initio implausibility

In accordance with a second line of case law, post-published evidence can only be disregarded if the skilled person would have had legitimate reasons to doubt that the purported technical effect would have been achieved on the filing date of the patent in suit. Such doubts may arise, for example, from the fact that either the application as filed or the common general knowledge on the filing date of the patent in suit give an indication that the purported technical effect can in fact not be achieved. In other words, post-published evidence must always be taken into account if the purported technical effect is not implausible. This line of case law applies a standard referred to in the following as the "ab initio implausibility" standard. The line of case law applying this standard is denoted in the following as the "ab initio implausibility line of case law".

13.5.1 An example of a decision that applies the ab initio implausibility standard is T 919/15, which concerned the use of herbicide combinations for controlling harmful plants ("weeds") in soybean crops, the combination having an active content of two different herbicides (A) and (B). While the application as filed contained experimental proof of a synergistic interaction for some combinations of herbicides falling under the definitions for (A) and (B), the proof of other combinations was submitted only after the filing date. The opponent argued that the synergistic interaction of herbicides was inherently unpredictable and that the application as filed did not make the synergistic effect plausible for the combinations for which only post-published evidence had been submitted. Therefore, the post-published data had to be disregarded for the assessment of inventive step.

The board in question did not agree. It reasoned (point 5.6 of the Reasons; translation provided and emphasis added by the current board):

"Thus, in the absence of evidence to the contrary in the common general knowledge for herbicide combinations containing herbicide (A), it cannot simply be assumed that a synergistic interaction would be per se implausible for the combinations not tested in the application as filed. This conclusion is in line with decision T 863/12, in which the plausibility of an effect was also confirmed on the basis of, inter alia, the fact that the common general knowledge did not contain any indications that could question this plausibility ..."

13.5.2 A further noteworthy example in this context is decision T 578/06. Here, claim 1 of the main request read as follows (emphasis added by the current board):

"[u]se of somatostatin ... in the formulation of a pharmaceutical ... preparation for the treatment of a human patient in receipt of transplanted isolated pancreatic islet cells, wherein the pharmaceutical composition is administered ..., whereby the functional life of the isolated transplanted pancreatic islet cells is extended relative to untreated transplanted isolated pancreatic islet cells."

In the appealed decision, the examining division had come to the conclusion that it was not plausible that the effect of extending the functional life of transplanted pancreatic islet cells could be obtained with the claimed subject-matter. The board, in overturning this decision and acknowledging plausibility of the effect, noted the following (points 13 and 15 of the Reasons; emphases added by the current board):

"The board notes that the EPC requires no experimental proof for patentability and considers that the disclosure of experimental data or results in the application as filed and/or post-published evidence is not always required to establish that the claimed subject-matter solves the objective technical problem. This is in particular true in the absence of any formulated substantiated doubt as is the case here."

"The board re-emphasises in this context however that this case law considers the establishment of plausibility only relevant when examining inventive step if the case at hand allows the substantiation of doubts about the suitability of the claimed invention to solve the technical problem addressed and when it is thus far from straightforward that the claimed invention solves the formulated problem."

After plausibility had been acknowledged, the board took the post-published evidence into account (point 17 of the Reasons).

13.5.3 Further decisions in line with the two above are T 536/07 (point 11 of the Reasons), T 1437/07 (point 38.1 of the Reasons), T 266/10 (point 37 of the Reasons), T 863/12 (point 7.3.3 of the Reasons), T 184/16 (points 2.4 to 2.7 of the Reasons) and T 2015/20 (point 2.7 of the Reasons). In all the decisions cited in section 13.5 applying the ab initio implausibility standard, plausibility was ultimately acknowledged.

13.5.4 The current board acknowledges that some of the decisions discussed above that apply the ab initio implausibility standard contain statements according to which they do not contradict T 1329/04, i.e. a decision considered by the current board to apply the ab initio plausibility standard. This would appear to imply that there is no divergence between the lines of case law applying the ab initio plausibility and the ab initio implausibility standard, respectively. However, close reading reveals that despite these statements, these decisions considered it decisive that there were no indications of doubt or reasons for implausibility on the filing date of the patent in suit (ab initio implausibility standard).

Furthermore, irrespective of whether a divergence is considered to exist, in this board's view at least, it is a fundamental question of law whether the ab initio plausibility or ab initio implausibility standard is to be applied.

13.5.5 The difference between the two lines of case law referred to above cannot be better illustrated than by the judgment of the UK Supreme Court of 14 November 2018, Generics (UK) (trading as Mylan) v. Warner-Lambert Company Ltd ("the UK Supreme Court decision") and the follow-up on this judgment by C. Floyd, "Plausibility: where from and where to", GRUR, 2021, 185. In the case underlying the UK Supreme Court decision, claim 3 at issue referred to the use of pregabalin for the preparation of a pharmaceutical composition for treating neuropathic pain. A central question to be answered was whether it was plausible at the priority date that the therapeutic effect of treating neuropathic pain could be achieved and whether, in view of this, the post-published evidence could be taken into account.

The majority opinion answered this question in the negative. It was held that the experimental data in the application as filed were predictive of efficacy for the treatment of inflammatory pain. But the application as filed did not claim that the experimental data presented made it plausible that pregabalin was effective for the treatment of any kind of neuropathic pain (point 42 of the decision). According to point 52 of the decision, it could:

"... not ... be enough to justify a monopoly that it is "possible" a priori that a drug which was effective for inflammatory pain would also be effective for neuropathic pain, in the absence of any reason to suppose that the possibility had some scientific basis or that it was more than speculative. Everything is possible that is not impossible, but "not impossible" is very far from being an acceptable test for sufficiency. Plausibility may be easy to demonstrate, but it calls for more than that."

So the majority in the UK Supreme Court decision seems to have applied what this board has termed the ab initio plausibility standard.

The minority opinion answered the above question in the positive. According to this opinion, the patent proprietor was not required to demonstrate within its patent a prima facie case of therapeutic efficacy (point 180 of the decision). Furthermore, according to point 181 of the decision (emphasis added by the board), recent decisions of the boards:

"... do not require that the patent discloses experimental evidence to demonstrate that plausibility unless there is an allegation, supported by sufficient evidence, that the invention does not work, ..."

It was also added (point 195 of the decision, emphasis added by the board) that:

"Only if a person skilled in the art would have significant doubts about the workability of the invention would it, in such a case, fail for insufficiency of disclosure."

Hence, the minority in the UK Supreme Court decision seems to have applied what the board has termed the ab initio implausibility standard.

13.6 No plausibility

A third line of case law seems to reject the concept of plausibility altogether. This third line of case law is referred to in the following as applying the "no plausibility" standard. The line of case law applying this standard is denoted in the following as the "no plausibility line of case law".

13.6.1 In T 31/18, the underlying application as filed related to pharmaceutical tablets comprising imatinib or pharmaceutically acceptable salts of it. The claim at issue was essentially directed to a tablet comprising imatinib and cross-linked polyvinylpyrrolidone in certain amounts. In view of the closest prior art, the patent proprietor formulated the problem essentially as the provision of imatinib tablets having a disintegration time of 20 minutes or less, and it also filed experimental evidence to prove that this problem had been solved. According to one of the opponents, this experimental evidence was not to be taken into account as it related to an effect which had not been plausibly shown to be achieved by the claimed tablets in the application as filed. The board held (point 2.5.2 of the Reasons) that:

"This line of argumentation appears to be incompatible with the assessment of inventive step according to the problem solution approach ... 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."

The board took the experimental evidence into account but held that it could not support the alleged effect of a low disintegration time vis-à-vis the closest prior art.

13.6.2 A similar decision was taken in T 2371/13. The claim at issue essentially concerned the use of a combination of two particular cationic direct dyes. In view of the closest prior art, the patent proprietor formulated the problem essentially as the provision of dye compositions having improved colour homogeneity. It also filed experimental evidence showing that this effect was achieved for the compositions tested. One of the opponents argued that the effect of an improved homogeneity had not been rendered plausible by the application as filed because the latter did not contain any experimental data in this respect. The effect was speculative and at the date of filing, no invention had been made. The board held (point 6.1.2 of the Reasons and catchword of the decision; translation provided by the current board) that:

"This line of argument is incompatible with the assessment of inventive step according to the problem-solution approach which requires that the state of the art closest to the invention be identified and that a technical problem in relation to that state of the art be formulated which problem is solved by the claimed subject matter. It is usual to invoke a technical effect for inventive step which is not explicitly mentioned in the application as filed."

"A lack of plausibility of an effect based on the absence of evidence in the patent application is not a sufficient reason to disregard comparative tests filed later to prove that effect. Dismissing them for this reason is inconsistent with the problem-solution approach which requires defining a technical problem from the closest prior art document, which is not necessarily the one cited in the patent application - see point 6.1 of the reasons."

The board took the patent proprietor's post-published data into account but considered it as not supportive of the effect over the entire breadth of the claim at issue.

13.7 Further considerations

13.7.1 The three lines of case law discussed above contain two extreme positions, one being a strict application of the ab initio plausibility standard and the other one applying the no plausibility standard. These two extremes illustrate that different results are obtained depending on which plausibility standard is applied. On the one hand, by applying the ab initio plausibility standard strictly, the ultimate result would be that patent applicants receive a patent only for embodiments for which experimental data or other substantiation is contained in the application as filed that makes the effect invoked for inventive step plausible for these embodiments. Hence, any extension of the claimed scope over what has been experimentally shown or otherwise substantiated in the application as filed would lead to refusal of the application. If, on the other hand, no plausibility standard were applied at all, a patent applicant could claim whatever it thinks might possibly be proven later to bring about a purported technical effect. This would give rise to what is often referred to in the case law as "speculative patenting" or "armchair inventions" where a monopoly is conferred to a patent applicant for mere speculation rather than a true invention. The ab initio implausibility standard in terms of its results appears to lie somewhere between these two extreme lines of case law.

13.7.2 On the other hand, requiring plausibility or at least the absence of implausibility to access post-published evidence can be particularly problematic in cases where an effect needs to be established vis-à-vis a prior-art document that has not been, and perhaps could not have been, considered by the patent proprietor/applicant. For instance, if a patent proprietor is confronted with a new closest prior document which makes a reformulation of the objective technical problem necessary, in particular under the ab initio plausibility line of case law, the patent proprietor would be barred from providing any evidence in support of the reformulated technical problem. This would mean a basically insurmountable hurdle for patentability once an opponent invokes a new closest prior-art document in opposition proceedings. Furthermore, such an approach would go against decades of case law which has allowed the reformulation of the technical problem in view of new closest prior-art documents and the reliance on post-published evidence in support of the newly formulated problem. In fact, the only hurdle applied in this case law has been that the newly formulated problem must be within the spirit of the invention as originally disclosed. See, for instance, T 1397/08, where it is stated in the catchword (translation provided and emphasis added by the current board; see also T 184/82 (point 5 of the Reasons)) that:

"According to the problem-solution approach for assessing inventive step in the field of chemistry, the technical problem can be reformulated, and in certain circumstances must even be reformulated, since for the objective determination of the problem, only the result actually achieved in relation to the closest state of the art counts. Nothing prevents, even at the appeal stage, the modification of the problem initially posed, provided that the spirit of the original statement of the invention is preserved ..."

The same follows from decision T 1422/12. In the case underlying that decision, a certain compound, namely crystalline tigecycline, was claimed. The effect relied upon was based on an improved stability with respect to epimerisation. This effect was not even mentioned in the application as filed. The board stated (point 2.3.2 of the Reasons, insertion in squared brackets by the current board) that:

"In this connection [i.e. well-established case law], any effects may be taken into account, so long as they concern the same field of use and do not change the character of the invention."

On this basis, the board took post-published evidence into account, concluded that the effect of improved stability was credibly shown and acknowledged inventive step.

13.7.3 An additional tension exists between the ab initio plausibility and ab initio implausibility standards on the one hand and the principle of free evaluation of evidence on the other hand (see G 3/97 (OJ EPO 1999, 245), point 5 of the Reasons and G 1/12 (OJ EPO 2014, A114), point 31 of the Reasons). It is not immediately clear what could be the legal basis for preventing the patent proprietor from relying on a particular type of evidence of a fact relevant to the outcome of the proceedings. Likewise, it is not clear on what basis a board would be prohibited from taking into account evidence it finds convincing and decisive.

13.7.4 In this respect, it should be stressed that, in accordance with Article 56 EPC, an invention must be considered as involving an inventive step if, having regard to the state of the art, it is not obvious to a person skilled in the art. There can thus be no doubt that inventive step can only be judged in relation to the prior art. The rationale developed in the ab initio plausibility line of case law is, however, that the invention had not been made on the filing date. This finding has been, and can only be, arrived at without considering any prior art. So it may be questionable whether Article 56 EPC is a proper legal basis for plausibility. Indeed, the legal basis for the requirement of plausibility has also been questioned elsewhere. In this respect, the current board would like to refer to the opinion expressed in the UK Supreme Court decision that plausibility "is a court-invented pre-condition to validity" (point 192 of the decision). In R. Jacob, "Plausibility and Policy", Bio-Science Law Review 17(6), 223, the author goes even a step further and states (page 223, first paragraph under "The Statutory Language") that:

"If one actually looks at the words of the EPC a purist would say it is straining the meaning of words beyond breaking point to get plausibility out of them - positively Humpty Dumpty-ish. I suppose it is for that reason that none of the judicial reasoning for getting the notion of plausibility out of either the definition of inventive step (obviousness) or sufficiency has much, or indeed anything, to do with the actual words in the statute. And the word plausibility itself is not in the statute - indeed is not, and never has been, in any patent statute anywhere."

Also in A. Slade, "Plausibility: a conditio sine qua non of patent law?", I.P.Q. 2020, 3, 180-203, the author considers Articles 56 and 83 EPC not to be a proper legal basis for the application of any plausibility standard. She advocates for Article 52(1) EPC as a legal basis since a speculative use of a known compound must fail the initial requirement of this article of being an invention. In this author's view, only if the requirement of Article 52(1) EPC is met can secondary requirements such as lack of inventive step be examined.

14. Conclusion

From the above, it is evident that a referral of questions to the Enlarged Board of Appeal is needed, both to ensure uniform application of the law and because points of law of fundamental importance have arisen. The three referral questions made in the order of the present decision relate to the three lines of case law discussed above, namely whether any plausibility standard can be applied at all (first referral question) and, if so, whether an ab initio plausibility standard (second referral question) or an ab initio implausibility standard (third referral question) is to be applied. The outcome of the referral is decisive for the case at issue since whether post-published evidence D21 can be taken into account depends on this outcome, and since, furthermore, as has been set out above, if taken into account, D21 is relevant to a final decision on inventive step.

15. During the oral proceedings, the board put on screen three preliminary referral questions (for details, see the minutes of the oral proceedings), to which the parties raised the following comments.

The appellant suggested that the questions should define the effective date more clearly. For example, in case of a patent claiming priority, it should be indicated whether the relevant date was the priority or the filing date.

The appellant also argued that it had to be made clear that the effect on which the respondent relied concerned the full ambit of the claim.

The respondent suggested that an additional question should address the burden of proof for (not) achieving the technical effect.

To address the appellant's first comment, the board has replaced "effective date" (which covers priority and filing dates) in the referral questions with "filing date". In the case at hand, evidence D21 was filed after the filing date of the patent in suit. Hence, the question whether evidence can be taken into account that the patent proprietor files after the priority date and before the filing date of the patent in suit does not arise in this case.

As regards the appellant's second comment, the board notes that a clarification that the effect concerns the full ambit of the claim is not deemed necessary. It is clear to the board that the respondent cannot successfully rely on an effect that only relates to a part of the claimed subject-matter (see e.g. T 939/92, points 2.4 to 2.6 of the Reasons).

The issue of the burden of proof for (not) achieving the technical effect raised by the respondent is important but is already encompassed by the current questions. Under the ab initio plausibility line of case law to which the second referral question refers, it is the patent proprietor that has to prove plausibility while in the ab initio implausibility line of case law, to which the third referral question refers, it is the opponent that has to show implausibility.

Order

For these reasons it is decided that:

The following questions are referred to the Enlarged Board of

Appeal for decision.

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)?