1.4. Examination of clarity post-grant

Art. 84 EPC is not a ground for opposition. However, when substantive amendments are made to a patent during an opposition, consideration has to be given to whether the amendments introduce any contravention of any requirement of the EPC, including Art. 84 EPC (T 301/87, OJ 1990, 335). In G 3/14 the Enlarged Board analysed whether, and if so to what extent, the requirements of Art. 84 EPC may be examined in opposition and opposition appeal proceedings, in particular if the amended claim is a mere combination of a granted independent claim and granted dependent claims or elements thereof. The Enlarged Board approved T 301/87 and held that, for the purposes of Art. 101(3) EPC, the claims may be examined for compliance with Art. 84 EPC only when, and then only to the extent that the amendment introduces non-compliance with Art. 84 EPC. G 3/14 has been applied in e.g. T 1977/13, T 1905/13, T 565/11, T 248/13, T 1287/14, T 2311/15, T 2321/15, T 1221/19 (clarity of adapted description). See also chapter IV.C.5.2.2 "Extent of power to examine amended claims for compliance with Article 84 EPC".

In G 2/19 (OJ 2020, A87), the Enlarged Board of Appeal held as follows:

Where, although a clarity objection based on Art. 84, second sentence, EPC is not a valid ground for opposition (Art. 100 EPC), a third party within the meaning of Art. 115 EPC chooses to file an "appeal" in order to have this objection nevertheless heard at a higher instance, this amounts to an attempt to circumvent the rules and is thus a clearly inadmissible means of redress.

In T 1661/16 the board found that independent claim 7 lacked clarity: the last feature, added during the opposition procedure and objected to by the appellant (opponent), left it unclear to the skilled person what further structural or functional limitation to the claimed arrangement could be implied by this feature. Rejecting different arguments from the patent proprietor, the board emphasised that the clarity requirement of Art. 84 EPC for an amendment was a substantive one, and that the subjective component in the task of interpretation was eliminated by taking the position of the skilled person. Thus it could objectively be concluded that the claim as amended was not clear. The meaning, in terms of the limiting effect, of features introduced into a claim must be clear in order that the claim as a whole was clear.