Amendments under the European Patent Convention

Article 123 of the European Patent Convention (EPC) relates to the amendments under the EPC, i.e. the amendments to a European patent application or patent, and notably the conditions under which they are allowable. In particular, Article 123(2) EPC prohibits adding subject-matter beyond the content of the application as filed, while Article 123(3) EPC prohibits an extension of the scope of protection by amendment after grant.

Article 123(1) EPC provides the right for an applicant, in proceedings before the European Patent Office (EPO), to amend its European patent application and for a patent proprietor (during opposition proceedings) the right to amend its European patent. This must however be done in accordance with the Implementing Regulations, considering that the applicant is given "at least one opportunity to amend the application of his own volition." According to the Implementing Regulations, amendments before receiving the (extended) European search report are generally not allowed, amendments are allowed in response to the extended European search report (i.e., in response to the communication under Rule 70a(1) or (2) EPC), and amendments are also allowed shortly after entry into European phase of a PCT application (namely, in response to the communication under Rule 161(1) EPC), but formally any further amendment is subject to the consent of the Examining Division.

Article 123(2) EPC provides that a European patent application, or European patent, may not be amended (during prosecution for an application, and after grant for a patent) in such a way that it contains subject-matter which extends beyond the content of the application as filed. In other words, an amendment cannot go beyond the original disclosure of the application. The amended subject-matter must be directly and unambiguously derivable (i.e., clearly and unambiguously derivable) from the content of the application as filed. "The underlying idea of Art. 123(2) EPC is that an applicant should not be allowed to improve his position by adding subject-matter not disclosed in the application as filed, which would give him an unwarranted advantage and could be damaging to the legal security of third parties relying on the content of the original application (...)." This legal provision illustrates the importance accorded by the Convention to the content of a European patent application as filed –i.e. on the filing date– in respect of its legal effects.

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