T 1976/19 11-05-2021

1. Clarity

1.1 Article 84 in combination with Rule 43(1) EPC stipulates that the claims shall be clear and define the subject-matter for which protection is sought in terms of the technical features of the invention. Those requirements serve the purpose of ensuring that the public is not left in any doubt as to which subject-matter is covered by a particular claim and which is not. From this principle of legal certainty it follows that a claim cannot be considered clear in the sense of Article 84 EPC if it does not unambiguously allow this distinction to be made (see also decision T 728/98, headnote and point 3 of the reasons).

1.2 Claim 1 as granted defines in feature [1.6] that the shape [of the bare stent] is a periodically changing shape to define proximal apices (32) having given radii of curvature (beta) and distal apices (34) having radii of curvature (alpha) smaller than said given radii of curvature (beta) of the proximal apices.

In the present main request as well as in auxiliary requests 1-9, this feature has been amended by introducing the term "significantly" before "smaller":

"[...] distal apices (34) having radii of curvature (alpha) significantly smaller than said given radii of curvature (beta) of the proximal apices"

Since the amendment derives from the description, it is to be examined under Article 84 EPC (G 3/14).

1.3 The introduced term "significantly" is a relative term, for which the appellant has not demonstrated that an unequivocal generally accepted meaning exists in the relevant art and which is not defined in the patent. In the context of claim 1, the objected term leaves it open as to how much smaller the radii of curvature of the distal apices have to be as compared to the radii of curvature of the proximal apices. As a consequence, it remains unclear which subject-matter is covered by the claim and which is not. The objected term, therefore, is not allowable under Article 84 EPC.

1.4 The appellant argued that the objected term was considered clear by the Opposition Division. In its decision, the Opposition Division found that "significantly" signifies that an observable difference between the two features being compared has to be present (point 16.5.2 of the reasons).

However, as correctly stressed by the respondent, whether something is "observable" is dependent on the manner in which the observation is made. Neither in the relevant art nor in the patent is there an indication as to whether "observable" means observable by the naked eye, or whether it means observable with measuring instruments and, if so, how precise those instruments need to be. The Opposition Division's construction of the term "substantially", therefore, is just as unclear as the objected term itself.

1.5 The appellant further argued that according to the case law of the Boards of Appeal, 9th edition 2019, chapter II.A.3.6, the use of a relative term in a claim may be accepted where the skilled person is able to understand the meaning of this term in a given context.

1.5.1 The appellant referred to page 18, lines 21-25, of the description as filed and argued that the objected term is linked to the effect of substantially preventing perforation of the blood vessel by the proximal apices, or, at a minimum, making it much less likely for the bare stent to perforate the vessel because of the less-sharp curvature of the proximal apices. According to the appellant, this effect could easily be verified by the skilled person, e.g. by simulations.

However, this effect is not part of the claim, so that it cannot be used to define its scope.

1.5.2 The appellant further referred to page 14, lines 13-15 and page 17, lines 20-23, and argued that in contrast to these passages, which recite (substantially) equal radii, the objected term denotes a difference which is "beyond substantially equal" or, in other words, "noticeable".

In the Board's view, the expression "beyond substantially equal" suffers from the same indefinite­ness as the objected expression "significantly smaller". Again, it is left open as to how large the difference of the compared radii has to be in order to be considered substantial.

Regarding the term "noticeable", the above observations with respect to the term "observable" apply (see point 1.4 above).

1.5.3 Consequently, even accepting the appellant's definition it remains unclear which subject-matter is covered by the claim and which is not.

1.6 For these reasons, the main request as well as auxiliary requests 1-9 are rejected under Article 84 EPC.

2. Auxiliary requests 10-19 - admission into proceedings

2.1 Auxiliary requests 10-19 were filed during oral proceedings and, hence, after notification of the summons to oral proceedings dated 14 May 2020. According to Article 13(2) RPBA 2020 they therefore shall, in principle, not be taken into account unless there are exceptional circumstances, which have been justified with cogent reasons by the party concerned.

2.2 The appellant argued that it was surprised by the Board's finding that the term "significantly" is unclear. The term had been considered clear by the Opposition Division and had not been objected to in the appeal proceedings before, at least not by the Board.

However, the respondent in its reply to the appeal (see point B.1. on pages 5 and 6) had argued in detail why the term "significantly" in its view is unclear. Also the Board in its communication of 21 August 2020 (see point 3.3.1 on page 6) had indicated that it needs to be discussed whether the relative term "significantly smaller" can clearly define the subject-matter for which protection is sought. The appellant, therefore, could not be taken by surprise that during oral proceedings the Board comes to the conclusion that the objected term is indeed unclear.

2.3 The appellant further argued that auxiliary requests 10-19 contain only simple amendments which clearly overcome the Article 84 EPC objection and which do not lead to any new objections such as under Article 123(2) EPC.

In the Board's view, this is not the case at least for the deletion of the term "significantly". This term had been introduced by the appellant in order to address the finding of the Opposition Division that claim 1 as granted contravenes Article 123(2) EPC (see point 14.2.2, item 3 of the reasons of the decision under appeal; see also point II.2.1 of the grounds of appeal). Deleting the term from claim 1, therefore, would again raise this issue, so that said amendment cannot be considered as clearly allowable.

2.4 For these reasons, auxiliary requests 10-19 are not admitted into the proceedings.