There has been considerably activity in the European Patent Office Boards of Appeal relating to the nature of "Grounds of Opposition" particularly with regard to their introduction in the proceedings after the Opposition has been filed.

The most important cases in this respect are the opinions handed down by the Enlarged Board of Appeal in G1/95 (Thomas de la Rue and Company Limited / GAO Gesellschaft für Automation und Organisation GmbH) and G7/95 (Ethicon, Inc. / United States Surgical Corporation). They concluded that, despite arguments that Article 100(a) EPC constituted a single ground of Opposition relating to lack of novelty, lack of inventive step and unpatentable subject matter, a ground of Opposition was an individual legal basis for objecting to the maintenance of the Patent. As such, lack of novelty, lack of inventive step and lack of patentable subject matter were individual grounds of Opposition.

In the first of the two cases (G1/95), it was held that an attempt to introduce the ground of unpatentable subject matter during Appeal proceedings, when the grounds had neither been mentioned nor substantiated in the Opposition nor introduced in the Opposition proceedings before the Opposition Division, was unallowable as an attempt to introduce a fresh ground of Opposition during the Appeal proceedings, without the agreement of the Patent proprietor.

In the second case (G7/95), the Opposition was substantiated solely on the ground of lack of inventive step and, only in Appeal proceedings, did the Opponent attempt to raise the objection of lack of novelty. The Enlarged Board of Appeal held that the ground of lack of novelty was a fresh ground of Opposition and would not be introduced into Appeal proceedings. However, in that particular case, the Enlarged Board of Appeal pointed out that, if the closest prior art document destroys the novelty of the claimed subject matter, the subject matter cannot involve an inventive step!

In T986/93 (Eton Corporation / Wabco Standard GmbH) the Technical Board of Appeal addressed the slightly different matter of introduction into Appeal proceedings of a ground of Opposition that had previously been rejected by the Opposition Division as having been introduced into the Opposition proceedings too late. In this respect, the ground of Opposition was first introduced at Oral Proceedings before the Opposition Division. Because the Enlarged Board of Appeal Decision No. G9/91 (Rohm and Haas Company / BASF Aktiengesellschaft) had held that fresh grounds of Opposition may not be introduced during Appeal proceedings without the approval of the Patentee, the Technical Board of Appeal had to decide therefore whether they could allow this late filed ground of Opposition into the Appeal proceedings. The Technical Board of Appeal concluded that the Enlarged Board of Appeal, by stating that 'fresh' grounds of Opposition may in principle not be introduced at the Appeal stage, were referring narrowly to any ground not introduced during Opposition proceedings (first instance) and were not referring to any grounds of Opposition not covered in the original Statement of Grounds. There was no reason that a ground of Opposition which was relied upon at any stage during Opposition proceedings should not be introduced into Appeal proceedings, even if the Opposition Division chose to disregard the belated submissions. In summary, it was held that a ground of Opposition introduced after the filing of the Statement of Grounds of Opposition, may be re-introduced later at Appeal proceedings.

Further refining this concept the Technical Board of Appeal in Decision No. T274/95 (Mars Incorporated / W.H. Münzprüfer Dietmar Trennar GmbH) held that a ground of Opposition, which is substantiated in the Notice of Opposition and which is not maintained during Opposition Proceedings may, subsequently, be re-introduced in the Appeal. The fact that the Opponent did not choose to continue with this ground of Opposition after the filing of the Statement of Grounds of Opposition should not prejudice the Opponent's right to rely upon such grounds during the Appeal and certainly does not make it a 'fresh' ground of Opposition.

Accordingly, it is important that an Opposition covers all possible grounds on which the Opponent may wish to rely both during Opposition and Appeal proceedings.