b) Case law around G 1/99 

According to T 809/99 a non-appealing patent proprietor is primarily restricted on appeal to defending the claims as maintained by the opposition division. If these claims are not allowable, the principle of prohibition of reformatio in peius applies, i.e. an amended claim which would put the opponent and sole appellant in a worse situation than if it had not appealed must be rejected. The board went on to say that the only exception to this principle as set out in G 1/99 requires consideration of a particular sequence of possibilities for overcoming the deficiency presented by the claim(s). The first solution for overcoming the deficiency to be considered (an amendment introducing one or more originally disclosed limiting features which would not put the opponent (appellant) in a worse situation than it was in before it appealed) in fact concerns a limitation of the scope of the claim. Such limitation can also be achieved by deleting the alternative embodiment in the claim, which led to the deficiency. The proprietor's argument that the limitation to only one of the two alternatives would render the scope of protection too narrow for it to be commercially interesting is not a valid reason for dismissing this solution and proceeding to the next possible solution indicated in G 1/99.

The respondent (patent proprietor) in T 1194/06 conceded that a limitation according to the first route mentioned in the decision G 1/99 (OJ 2001,381) was possible but argued that this would result in a substantial restriction of the scope of the claims. The board was aware of the fact that the respondent would lose part of the protection afforded by the patent as maintained by the opposition division. It was, however, clear from G 1/99 that the principle of reformatio in peius had to be respected by the boards of appeal and that an exception to this principle should be construed narrowly. There was no reason to assume that the Enlarged Board of Appeal in G 1/99 considered even a substantial limitation of the scope of protection unacceptable.

The board in T 1033/08 made it clear that G 1/99 did not supersede G 9/92 date: 1994-07-14 and G 4/93, but was complementary thereto in that it gave directions for allowing an exception to the principle of prohibition of reformatio in peius as defined in these decisions. Certain conditions had to be fulfilled. A limiting feature introduced during the opposition procedure had to be deleted. The necessity for its deletion had to be caused by the appeal. This meant that the deletion was necessary and appropriate because it was related to a ground of opposition and caused by new facts, evidence or arguments put forward by the appellant, or because of a different evaluation of the situation by the board of appeal. Without the deletion, the patent would have to be revoked. It was not possible to overcome the objection by introducing new features which limit the scope of the patent as maintained. Only if these preconditions were fulfilled, might an objection be overcome by introducing new features which extended the scope of the patent as maintained, but within the limits of Art. 123(3) EPC according to the second option of G 1/99.

In T 2129/14 the inadmissible amendment concerned four elements of the claimed system and some relationships between them. Compared with claim 1 of the request found allowable by the opposition division, in claim 1 of the second auxiliary request three features were deleted. As a result, the protection was extended compared to the request on the basis of which the patent would have been maintained if the opponent and sole appellant had not appealed. Under such circumstances the opponent and sole appellant was in a worse situation than if it had not appealed. The Enlarged Board laid down the conditions under which the exception may be made. The board noted that the three conditions laid down by G 1/99 are sequential. Further, the board noted that in claim 1 of the second auxiliary request features had been added which also involved some relationships between the four elements of the system. In the board's opinion, each of the requirements lost by deleting the inadmissible amendment had to be considered together with the added features, in the light of the conditions established in G 1/99. The board came to the conclusion that the amendments fell within the conditions for an allowable exception under G 1/99, allowing the deletion of the former inadmissible amendments, and were therefore allowable.