4.1. Relationship of Rule 139 EPC with Article 123(2) and (3) EPC

In opinion G 3/89 (OJ 1993, 117) and decision G 11/91 (OJ 1993, 125) the Enlarged Board held that corrections under R. 88, second sentence, EPC 1973 (now R. 139, second sentence, EPC) were special cases of an amendment within the meaning of Art. 123 EPC and fell under the prohibition of extension laid down in Art. 123(2) EPC.

The parts of a European application or patent relating to the disclosure (description, claims and drawings) can be corrected only within the limits of what the skilled person would derive directly and unambiguously, using common knowledge and seen objectively and relative to the date of filing, from the whole of these documents as originally filed. Such a correction was of a strictly declaratory nature and thus did not infringe the prohibition of extension under Art. 123(2) EPC 1973.

For case law on these issues prior to G 3/89 and G 11/91, see the summary of facts and submissions of those decisions, and "Case Law of the Boards of Appeal", 7^th ed. 2013, II.E.4.1. For a summary of the findings in G 3/89 and G 11/91, see also G 2/95 (OJ 1996, 555, point 2 of the Reasons).

In T 1946/16 the board recalled that a correction under R. 139, second sentence, EPC was a special case of an amendment within the meaning of Art. 123 EPC and that the requested correction would have to meet the requirements of Art. 123(3) EPC. The board in T 2058/18 likewise noted that Art. 123(2) EPC applied to all amendments to the patent application or the patent; these included corrections of the description, claims or drawings under R. 139, second sentence, EPC.