R. 137(5) EPC as in force from 1 April 2010 (OJ 2009, 299) (former R. 137(4) EPC and R. 86 (4) EPC 1973) relates to amendments made during the grant procedure which are under the control of the examining division. It stipulates that amended claims may not relate to unsearched subject-matter which does not combine with the originally claimed invention or group of inventions to form a single general inventive concept. Nor may they relate to subject-matter not searched in accordance with R. 62a or R. 63 EPC.

In T 2459/12 what was at issue was whether the invention is "unsearched" within the meaning of R. 137(5) EPC, which limits the choice of subject-matter which may be put forward by way of amendment for examination in the European procedure. The board stated that it was clear that the only interpretation of R. 137(5) EPC was that, within the meaning of R. 137(5) EPC, "unsearched" means "unsearched by the EPO". It was consequently the view of the board that where, following the drawing up of a supplementary European search report by the EPO, an applicant files amended claims seeking protection for subject-matter not covered by the supplementary European search as a result of the application of R. 164(1) EPC as then in force, an objection under R. 137(5) EPC should be raised.