b) Correction of errors 

In T 2450/17 the patent specification contained an incorrect reference to the prior art as a result of an amendment during the grant proceedings. At the oral proceedings before the board, the appellant submitted an amended paragraph from which the inaccurate information had been deleted. As to whether the contested amendments were admissible under R. 80 EPC, the board pointed out that the case law had recognised that references to relevant prior art as defined in R. 42(1)(b) EPC could be added at a later stage without this necessarily being deemed an inadmissible extension of the subject-matter of the application. However, such references designed to delimit the relevant prior art should not be incorrect or misleading, otherwise they could indeed alter the subject-matter of the patent. Remedying inaccuracies of this kind thus did not contravene Art. 123(2) EPC; on the contrary, doing so was appropriate and necessary for ensuring compliance with that provision. Deleting incorrect information about the prior art from which the patent specification was to be distinguished was thus appropriate for addressing the ground for opposition under Art. 100(c) EPC. The board also concluded that it was wrong to say that any amendment to an incorrect reference to the prior art permitted under R. 80 EPC (as it was occasioned by Art. 100(c) EPC) automatically constituted a breach of Art. 123(3) EPC. It noted that R. 80 EPC was satisfied if the patent documents were amended to overcome a potentially relevant ground for opposition and that, in the case in hand, the scope of protection had not been extended.

In T 2444/18 the board held that the fact that there was an error in certain amended claim requests could not be used to prevent the patent proprietors from stating the back-references correctly in another claim request. R. 80 EPC did not apply to such a situation as it concerned amendment(s) of a European patent, i.e. a comparison of an amended version to the granted version rather than a comparison between different amended versions. A different understanding of the legal framework would create a legal asymmetry. On the one hand, any amended text would have to comply with all the requirements of the EPC. On the other hand, any subsequent amendments of that text could be allowed only if they were prompted by a ground for opposition.