The Enlarged Board of Appeal held in G 1/03 and G 2/03 (OJ 2004, 413 and 448) concerning undisclosed disclaimers that an amendment to a claim by the introduction of a disclaimer may not be refused under Art. 123(2) EPC 1973 for the sole reason that neither the disclaimer nor the subject-matter excluded by it from the scope of the claim have a basis in the application as filed. It considered that the following criteria were to be applied for assessing the allowability of a disclaimer which was not disclosed in the application as filed:

A disclaimer may be allowable in order to:

- restore novelty by delimiting a claim against state of the art under Art. 54(3) and (4) EPC 1973;

- restore novelty by delimiting a claim against an accidental anticipation under Art. 54(2) EPC 1973; an anticipation is accidental if it is so unrelated to and remote from the claimed invention that the person skilled in the art would never have taken it into consideration when making the invention; and

- disclaim subject-matter which, under Art. 52 to 57 EPC 1973, is excluded from patentability for non-technical reasons.

In addition, a disclaimer should not remove more than is necessary either to restore novelty or to disclaim subject-matter excluded from patentability for non-technical reasons. On the other hand, a disclaimer which is or becomes relevant for the assessment of inventive step or sufficiency of disclosure adds subject-matter contrary to Art. 123(2) EPC 1973. And a claim containing a disclaimer must meet the requirements of clarity and conciseness of Art. 84 EPC 1973.

In G 1/03 (and G 2/03), the Enlarged Board, having regard to the law established by it in relation to disclaimers, expressly identified those board decisions which should no longer be applied. Thus, the Enlarged Board stated that the isolated decisions T 170/87 and T 313/86 were not to be followed, whilst also criticising T 323/97 in the light of the new law applicable.