In G 1/93 (OJ 1994, 541) the Enlarged Board of Appeal ruled on the question of "limiting extensions" as follows:
If a European patent as granted contained subject-matter which extended beyond the content of the application as filed within the meaning of Art. 123(2) EPC 1973 and which also limited the scope of protection conferred by the patent, such patent could not be maintained in opposition proceedings unamended, because the ground for opposition under Art. 100(c) EPC 1973 prejudiced the maintenance of the patent. Nor could it be amended by deleting such limiting subject-matter from the claims, because such amendment would extend the protection conferred, which was prohibited by Art. 123(3) EPC 1973. Therefore, in principle, if the European patent as granted contained a "limiting extension", it had to be revoked. Art. 123(2) and 123(3) EPC 1973 were mutually independent of each other. In this sense, it had to be admitted that Art. 123(2) EPC 1973 in combination with Art. 123(3) EPC 1973 could operate rather harshly against an applicant, who ran the risk of being caught in an inescapable trap and losing everything by amending his application, even if the amendment was limiting the scope of protection. However, as submitted by the opponent, this hardship was not per se a sufficient justification for not applying Art. 123(2) EPC 1973 as it stood in order to duly protect the interests of the public. Nor did it, in principle, matter, that such amendment had been approved by the examining division. The ultimate responsibility for any amendment of a patent application (or a patent) always remained that of the applicant (or the patentee).
The Enlarged Board, however, also mentioned three other instances:
- If the added feature could be replaced by another feature disclosed in the application as filed without breaching Art. 123(3) EPC 1973, the patent could be maintained (in amended form). This might turn out to be a rare case in practice (see below T 166/90).
- An added undisclosed feature without any technical meaning could be deleted from a claim without violating Art. 123(3) EPC 1973.
- An added feature, which did not provide a technical contribution to the subject-matter of the claimed invention but merely limited the protection conferred by the patent as granted by excluding protection for part of the subject-matter of the claimed invention as covered by the application as filed, was not considered as subject-matter which extended beyond the content of the application as filed within the meaning of Art. 123(2) EPC 1973. In this case also the patent could be maintained.
Board of Appeal 3.4.02 noted in T 335/03 that, according to G 1/93, there was no basis in the Convention for providing a claim with a footnote to the following effect; "This feature is the subject of an inadmissible extension. No rights may be derived from this feature"; in other words, in cases of conflict between Art. 123(2) and Art. 123(3) EPC 1973 the footnote solution is inadmissible (see also T 307/05).
On the basis of decisions G 1/93 and G 1/03 dealing with Art. 123(2) and (3) EPC 1973 and with disclaimers, the board in T 1180/05 came to the conclusion that the deletion of a feature in a granted claim, which feature extended beyond the content of the application as filed, and its reintroduction in the form of a disclaimer, so that the subject matter of the claim remained the same, was not suitable to overcome the potential conflict between paragraphs 2 and 3 of Art. 123 EPC 1973. The board decided not to refer the question to the Enlarged Board of Appeal as requested by the patent proprietor. The decision of the opposition division maintaining the patent in amended form was set aside and the patent revoked.