According to G 1/03 (OJ 2004, 413), a disclaimer which makes a technical contribution, in particular which is or becomes relevant for the assessment of inventive step or sufficiency of disclosure, adds subject-matter contrary to Art. 123(2) EPC (point 2.3 of the Order; point 2.6 of the Reasons). In G 1/16 the Enlarged Board endorsed the concept that the undisclosed disclaimer may not be related to the teaching of the invention and provided the following clarifications: Introducing any disclaimer into a claim necessarily changes the technical information. The question to be asked in this context is not whether an undisclosed disclaimer quantitatively reduces the original technical teaching – this is inevitably the case – but rather whether it qualitatively changes it in the sense that the applicant's or patent proprietor's position with regard to other requirements for patentability is improved. If that is the case, then the original technical teaching has been changed by the introduction of the disclaimer in an unallowable way.

In T 788/05 the undisclosed disclaimer was introduced by the appellant during the examination procedure with the purpose of establishing the novelty of the claimed subject-matter with respect to D1, which was then considered as a prior art document relevant under Art. 54(3) EPC 1973. In the case at issue, the relevant prior art was represented by documents D1 and D5. To be allowable the disclaimer had to fulfil the conditions in relation to both documents. As far as D1 was concerned, the disclaimer appeared to be appropriate. D5 represented the state of the art under Art. 54(2) EPC 1973. As D5 was not state of the art under Art. 54(3) and (4) EPC 1973 and was not an accidental disclosure, the disclaimer would only be allowable if it did not add subject-matter within the meaning of Art. 123(2) EPC 1973, i.e. if the disclaimer did not become relevant for the assessment of inventive step. Going into details, the board concluded that the subject-matter of claim 1 of the main and the first auxiliary requests was not acceptable under Art. 123(2) EPC 1973 (see also T 761/08).

In T 660/14 claim 1 of auxiliary request 4 contained two additional features according to which the operating and control members of the claimed bicycle control device were pivotable about non-common offset axes and were not pivotable commonly about either of the offset axes. The board, applying the criterion of G 1/03 as interpreted by G 1/16, considered that the disclaimers provided a technical contribution to the subject-matter disclosed. Claims 7 and 8 as filed addressed the operating member and the control member being arranged to be pivotable about parallel and/or offset axes. As indicated in the description, this may be seen as providing ergonomic advantages. The board concluded from this that the disclaimers introduced a technical difference to the amended claim when compared to the content of the original application. The pivotable arrangement of the operating and control members about the axes was of a technical nature, not least through the disclosure of the ergonomic benefits; the board concluded the disclaiming of this arrangement would have to be as well. The board held that this finding was furthermore confirmed by considering whether merely a quantitative change to the original technical teaching had occurred or indeed whether a qualitative change had resulted from the introduction of the undisclosed disclaimers (G 1/16). By disclaiming both common offset axes and common pivoting about either of the offset axes, the ergonomic considerations identified in the application as filed had been modified, resulting in a qualitative change to the originally disclosed technical teaching in the sense that the proprietor's position with regard to inventive step would be changed. See also T 2000/14, in which the board also found that the disclaimer lead to a qualitative change to the originally disclosed technical teaching.