The European patent as granted or as amended in opposition proceedings determines retroactively the protection conferred by the European patent application, insofar as such protection is not thereby extended.

Opposition proceedings will frequently give rise to amendments to the claims, following from grounds for opposition raised under Art. 100. Reasoned requests filed independently by the proprietor of the patent for an amendment to the claims, e.g. for limitation of the patent in view of an aspect of the state of the art which has come to his knowledge, may also result in amendments to the claims after examination by the Opposition Division.

In such cases the claims of the European patent may not be amended in such a way as to extend the protection conferred by the patent.

The extent of protection conferred by a European patent is determined by the claims. Nevertheless, the description and drawings are to be used to interpret the claims.

The Protocol on the Interpretation of Art. 69, which is, pursuant to Art. 164(1), an integral part of the EPC, specifies how Art. 69 is to be interpreted.

Since, pursuant to Art. 69(1), amendments to the description and drawings will also influence the interpretation of the claims, and may therefore extend the protection conferred, any such amendments extending protection in this way are not allowable (see G 1/93, OJ 8/1994, 541).