Where a European application does not derive from an earlier international application, the applicant may not amend the claims before receiving the European search report (Rule 137(1)). Consequently, in these cases, the search is directed to the claims as originally filed, in the European application, or to the set of claims filed according to Rule 57(c) or 58.

However, where a European application derives from an earlier international application, the applicant may have amended the international application in the international phase, either after receipt of the international search report (Art. 19(1) PCT) or during international preliminary examination (Art. 34(2)(b) PCT). The applicant may then specify that he wishes to enter the European phase with these or otherwise amended application documents (including claims) according to Rule 159(1)(b). Furthermore, the applicant is given the opportunity by the EPO to amend the application documents (including the claims) within a set time limit (Rule 161). The application as amended serves as the basis for any supplementary European search which has to be performed pursuant to Art. 153(7) (see II, 4.3 and XII, 2).