The provision of Art. 115(1) EPC, second sentence, that a third party shall not be "a party to proceedings before the European Patent Office" assumed that proceedings were pending before the EPO.
In T 580/89 (OJ 1993, 218), observations submitted by a third party were not added to the file until after the decision had been taken and therefore not considered.
In T 690/98 the question arose of whether observations filed by a third party could give rise to a reassessment by the Office of its own motion, under Art. 114(1) EPC 1973, of the patentability of the subject-matter of the contested patent, even if the appeal proved to be inadmissible. In the board's view, the answer was no, since the admissibility of an appeal, according to Art. 110(1) EPC 1973, was a prerequisite for examination of the appeal. The substance of the contested decision could only be examined when admissibility was established. Therefore, objections by third parties lodged at the appeal stage were not to be examined by the Office of its own motion as there no appeal proceedings were pending.