2.1. Purpose of Article 123(3) EPC

Article 123(3) EPC is examined in post-grant proceedings, i.e. opposition and limitation proceedings (Art. 105a EPC); as regards nullity proceedings before national courts, see Art. 138(1)(d) EPC (corresponding to Art. 123(3) EPC).

Article 123(3) EPC is directly aimed at protecting the interests of third parties by prohibiting any broadening of the claims of a granted patent, even if there should be a basis for such broadening in the application as filed (G 1/93, OJ 1994, 541) (T 2461/17). In accordance with the general intention of Art. 123(3) EPC, there should be legal certainty for the activities of third parties trusting that the protection conferred by a patent can only be restricted, but not extended (T 1149/97, T 2450/22).

The object of Art. 123(3) EPC is to prevent any procedural situation where an act which does not infringe the patent as granted becomes an infringing act as a result of an amendment after grant (see T 1149/97, T 1898/07 referring to T 59/87 date: 1988-04-26, OJ 1988, 347 and T 604/01).