Art. 123(3) EPC is worded as follows: "The European patent may not be amended in such a way as to extend the protection it confers." This refers to the patent as a whole; Art. 123(3) EPC thus contains a substantive clarification. This principle is applicable in all proceedings before the EPO.
Art. 123(3) EPC provides that during opposition proceedings the claims of the European patent may not be amended in such a way as to extend the protection conferred upon grant. 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. In accordance with the established case law of the boards of appeal, the legal notion "protection conferred" in Art. 123(3) EPC refers to the totality of protection established by the claims as granted and not necessarily to the scope of protection within the wording of each single claim as granted. Under Art. 123(3) EPC, the patentee is generally allowed to redraft, amend or delete the features of some or all claims and is not bound to specific terms used in the claims as granted as long as the new wording of the claims does not extend the scope of protection conferred as a whole by the patent as granted (and does not violate the requirements under Art. 123(2) EPC). Thus, in order to assess any amendment under Art. 123(3) EPC after grant, it is necessary to decide whether or not the totality of the claims before amendment in comparison with the totality of the claims after amendment extends the protection conferred (cited from T 1898/07).