CABINET CHAILLOT

T2716/19 - Admissibility of late filed documents

Admissibility of late filed documents - Article 12 RPBA - Inventive step

The appeals lodged by opponents lie from the interlocutory decision of the opposition division, according to which European patent No. 2 682 397 (the patent) as amended in the form of auxiliary request 6 meets the requirements of the EPC.
Claim 1 of auxiliary request 6 found allowable by the opposition division reads as follows:
"1. A method for the manufacture of 9-[2-(phosphonomethoxy)propyl]adenine (PMPA) comprising reacting 9-(2-hydroxypropyl)adenine (HPA), magnesium t-butyl or isopropyl oxide, and protected p-toluenesulfonyloxymethylphosphonate."
However, for the then auxiliary request 6, now the main request, the opposition division was convinced that a technical effect over the same closest prior art had been credibly shown to derive from the specific use of magnesium t-butyl oxide as the base. Therefore, this technical effect could be acknowledged for the subject-matter of claim 1 of the then auxiliary request 6 in view of the restriction of the base used in the method to magnesium t-butyl or isopropyl oxide.
The respondent filed D24 about two weeks in advance of the oral proceedings before the opposition division. It argued that this document represented a reaction to new objections raised by the appellant in the letter dated 18 April 2019, i.e. two months before the oral proceedings, which were based on document D21 filed with the same letter.
The opposition division concluded that the objections raised by the appellant in the letter dated 18 April 2019 had already been raised at least by opponent 1 in its notice of opposition. Therefore, the respondent could have filed D24 with its reply to the oppositions. Thus, D24 was late filed. In addition, the opposition division considered D24 not prima facie relevant for the inventive step of claim 1 of the then main request. Thus, the opposition division decided not to admit D24 into the proceedings. In its decision, the opposition division did not deal with whether D24 was prima facie relevant for any of the auxiliary requests, including auxiliary request 6 that it found allowable.
In accordance with decision G 7/93, the board can overturn the non-admittance decision by the opposition division only if the latter exercised its discretion according to the wrong principles, without taking into account the right principles or in an unreasonable way.
For the sake of argument only, it is assumed that the opposition division correctly concluded that D24 could have been filed with the reply to the oppositions and thus that it was late filed. Under this assumption, the opposition division correctly assessed whether D24 was prima facie relevant for maintaining the then main request when deciding on the admittance of this document.
However, the assessment of the prima facie relevance of D24 should not have been limited to the subject-matter of claim 1 of the then main request. It should have extended to the subject-matter of the auxiliary requests on file, especially the subject-matter of claim 1 of the then auxiliary request 6 (now the main request).
Therefore, the opposition division, when deciding on the admittance of D24, while using the correct criterion of prima facie relevance, did use it in an unreasonable way because it limited its assessment to the subject-matter of the then main request.
Since the respondent referred to D24 in its reply to the grounds of appeal, i.e. at the earliest possible stage of the appeal proceedings, and based its inventive-step case on it, the board concludes that D24 should be part of the appeal proceedings.
The subject-matter of claim 1 of the main request differs from the disclosures only in that magnesium t-butyl oxide or magnesium isopropyl oxide is used in lieu of lithium t-butoxide.
The respondent argued the application demonstrated an improvement in the yield in the reaction of HPA to PMPA when magnesium t-butyl oxide or magnesium isopropyl oxide was used as the base instead of lithium butoxide. This improvement was confirmed by each of the post-published documents D18 to D21 and D24. The respondent formulated the objective technical problem as the provision of an improved process, in particular providing an improved yield of PMPA.
The appellant argued that the application as filed did not make the above-mentioned technical effect brought forward by the respondent plausible. Accordingly, in the absence of plausibility based either on the application as filed or common general knowledge, the opposition division was incorrect to allow the respondent to rely on post-published evidence.
The improvement of the PMPA yield in a reaction starting from HPA by using the alkoxides defined in the current main request relied on by the respondent was encompassed by the technical teaching and embodied by the invention originally disclosed in the application as filed. In line with decision G 2/21, this technical effect can thus be relied on by the respondent, and post-published evidence confirming this technical effect cannot be disregarded.
The board holds that the objective technical problem should at least be seen as the provision of a method achieving an improved yield of PMPA.
The appellant did not indicate any document disclosing or suggesting that replacing lithium-t-butoxide with either magnesium t-butyl oxide or magnesium isopropyl oxide improved the yield of PMPA. Nor did it rely on common general knowledge.
Therefore, the skilled person facing the above-mentioned objective technical problem would not have been prompted by any available document or common general knowledge to replace the lithium-t-butoxide used in the method of the closest prior art with either magnesium t-butyl oxide or magnesium isopropyl oxide as required by claim 1 of the main request.
For these reasons, the board concludes that the subject-matter of claim 1 of the main request involves an inventive step within the meaning of Article 56 EPC. Therefore, the main request is allowable.
The appeal is dismissed.

 

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