T 0809/99 of 22.10.2002

On appeal the non-appealing patent proprietor is primarily restricted 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 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 (reasons 2.4).