CASELAW-EPO - reviews of EPO Boards of Appeal decisions

T 375/21 – Prima facie relevance for late submissions, especially for a late filed ground of opposition

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The patent relates to the use of compositions for the prevention and/or treatment of pathologies related to alpha-glucosidase and especially to the use of compositions for the prevention and/or treatment of type 2 diabetes.

Brief outline of the case

The OD admitted in the procedure the late filed ground of opposition under Art 100(b).

For the OD, the disclosure did not contain sufficient information to make it credible that the skilled person could use the AP peptide to treat or prevent diabetes with a dose other than 5 or 3000 mg.

The OD did not admit AR 1 to 3, submitted during OP.

The patent was thus revoked for lack of sufficiency

The proprietor appealed the revocation.

The board held that the late ground of opposition should not have been admitted by the OD and remitted the case to the OD for examination of IS.

The case is interesting as it deals with the admissibility of the late ground of opposition by the OD.

The opponent’s position

The new ground of opposition was submitted in response to documents D16 and D18 (in particular D16) filed by the proprietors with their response to the notice of opposition.

Document D16 reports a clinical trial of AP dipeptide and the authors indicated that for a certain dosage of AP dipeptide, no significant difference was observed compared to placebo.

Document D16 is a post-published scientific article, which cannot be easily found in a prior art search. Document D18 is an internal and confidential report dating from May 2020 and is not accessible to third parties.

Consequently, the new ground for opposition could not have been raised earlier, as the Opposition Division rightly mentions in its decision.

Reading D16 also reveals that a very relevant biological response was observed (postprandial glycaemia; see e.g. paragraph [0042] of the patent), and that the authors concluded that the “high dose” (containing 7.68 mg AP dipeptide) did not provide a significantly different therapeutic effect from placebo.

Identification of this highly relevant teaching requires only reading of D16 by a person skilled in the art; no further assumption or speculation is required to reach the conclusion that the embodiments according to the subject matter of the claim do not have the stipulated therapeutic effect – this is explicitly stated by the authors, and D16 therefore meets the “prima facie relevance” criterion.

The proprietors’ position

For a ground for opposition to be prima facie relevant, a degree of conviction beyond reasonable doubt must be applied.

However, the doubt that the opponent attempted to raise by invoking D16 is contradicted by the data in D18 which, in part 2 of the report, clearly demonstrates that a product containing 500 mg/kg of Pep2dia® has a significant effect on blood sugar levels in mice, which can easily be converted into a dosage of 8 mg for a 75 kg human.

Contrary to what the OD indicated in its decision, D18 therefore clearly shows that a dosage of 8 mg is effective in the treatment or prevention of type 2 diabetes.

Furthermore, statistically insignificant data, i.e. with inappropriate power for the high dose (7.68 mg AP), does not allow the conclusion to be drawn that there was no effect in the clinical study presented in D16.

D16 is therefore not “prima facie relevant” to the high dose and does not justify the introduction of a new ground opposition.

The OD’s position

In its decision, the OD gave several reasons for admitting the new ground:

1) The ground was not late, as it represented “a reaction to documents D16 and D18 submitted by the proprietor with its reply to the notice of opposition” [and that] “this objection could not have been raised beforehand

2) The fact that “the proprietor himself suggested the need to hear from a technical expert as part of the sufficiency of the disclosure, […] is a clear sign that this point needs to be discussed”

3) That “it must be discussed whether the disclosure of D16 and D18 casts serious doubt on the fact that a person skilled in the art could carry out the invention as defined in claims 1 to 4 by following the instructions in the patent”, shows that the late ground of opposition is relevant.

4) The proprietor has not provided […] any reasons why this ground would not be relevant. On the contrary, the proprietor’s arguments were mainly related to the substance of the sufficiency of the disclosure.

The board’s position

In its decision, the OD did not recognise the late nature of the ground for opposition under Art 100(b). The decisive factor in determining whether a new ground for opposition is late is whether the ground was mentioned in the notice of opposition or omitted from it.

In the present case, the new ground is clearly belated, as it was not presented in the notice of opposition and was raised for the first time two months before the OP.

In its decision, the OD did not indicate why the new ground was prima facie relevant. Although this criterion is mentioned at the beginning of section 4 in the decision, it is not mentioned again thereafter.

The statement that “it must be discussed whether the disclosure of documents D16 and D18 casts serious doubts seems rather to suggest that the OD considered the presence of serious doubts to be questionable, which is the opposite of the prima facie relevance principle.

Accordingly, an examination of the content of documents D16 and D18 in the contested decision and the need to interpret the results disclosed in those documents demonstrate that the OD considered a detailed analysis of document D16 to be necessary in order to assess its relevance.

The fact that the proprietors suggested “the need to hear from a technical expert as part of the sufficiency of the disclosure” represents an attempted defence under Art 113(1), which cannot be taken as an indication that the new ground was prima facie relevant.

The OD was also in error when it asked the proprietors to give reasons why the “ground would not be relevant”. According to Opinion G 10/91, it is rather for the OD to explain why, prima facie, the new ground appears to be wholly or partly opposed to the maintenance of the contested patent.

In conclusion, the board set aside the OD’s decision to admit the new ground of insufficient disclosure

The Board concluded that the new ground of opposition should not have been admitted in the proceedings. The criteria of prima facie relevance was not fulfilled.

The preparations used according to document D16 contain a mixture of peptides, in the form of milk protein hydrolysate, with 94.5% low molecular weight peptides. The evidential value of the results reported for the specific effect of the AP peptide, present in a ratio of on average 0.96 mg out of 350 mg, is therefore uncertain. D16 refers to the effects of milk peptides rather than those of the AP peptide.

The Board noted that D16 does not consider that the results demonstrate a lack of efficacy of the high dose; it only states that these results lack statistical significance.

Statistical significance (p-value) is a relative value that does not make it possible to conclude that a fact is true or false, but which gives an indication of the probability of obtaining the observed results of a test, assuming that the null hypothesis, same effect as placebo, is correct.

D18 concerns a study on rats using the same product as that used in document D16. In its reply to the statement of grounds of appeal, the opponent relies solely on document D16 for its argument regarding the lack of sufficiency.

For these reasons, the board did not consider either D16 or D18 to be prima facie relevant and found the new ground of lack of sufficiency to be inadmissible.


In admitting late submissions of the opponent, that is any submission filed after the end of the 9 months opposition period, the criterion of prima facie relevance is the key criterion.

If a late submission is not prima facie relevant it should not be admitted. An abuse of procedure can also lead to the non-admissibility before an OD.  

The present case is interesting in that it is not so frequent that a board sets aside a discretionary decision of an OD in matters of late submissions, especially in matters of grounds of opposition.

Not having been admitted in first instance, makes very difficult for a submission in appeal to be admitted. Not only, we have G 10/91, but the valid RPBA put a further obstacle for a late ground of opposition to be admitted.

For the board the OD took the wrong conclusions in matters of prima facie relevance when it came to the ground of opposition under Art 100(b).  

This went as far as to require from the proprietor to show that the late filed ground would not be relevant, contrary to G 10/91, which gives the burden to the OD to assess whether the late filed ground is relevant or not. This kind of shifting the onus of proof is not correct.

The late filed ground of lack of sufficiency was based on a document which needed a careful and pointed analysis. This is not a sign that a document is prima facie relevant and can, prima facie, support a new ground of opposition.  Moreover this document was contradicted by a further document supporting a therapeutic affect.

On the other hand, a lack of sufficiency has to be decided on the basis of the originally filed documents and not on the basis of a doubtful post-published document.

In view of the comments from the board, it is also possible to conclude that the OD had a rather cursory reading of the content of D16. D18 was actually giving a different message than D16.

It should however not be forgotten that being in a position to decide on Art 100(b) avoids any discussion on N or IS.

In view of the production pressure imposed on OD’s, the way the OD handled the case does thus not really come as a surprise.

To the defence of the OD, the board endorsed the OD’s decision to admit D26/D26t and not to admit D27 and D28 late filed by the opponent. D26/D26t was considered prima facie relevant but D27 and D28 were not.  

As the decision has been set aside, the proprietor will be in a position to file new AR.

The present decision also confirms the trend that, since the beginning of 2023, more than 50% of decisions of ODs are set aside by a board. This figure is rather worrying.


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