In T 998/99 (OJ 2005, 229) the board held that Art. 87(1) EPC 1973 made no provision for multiple filings in the same country within the priority period for the same subject-matter and hence the same invention in conjunction with the same priority document. As derogations had to be interpreted strictly, only the first filing could validly claim priority. Neither Art. 4.G(1) of the Paris Convention nor its equivalent in the EPC 1973 (Art. 76(1), second sentence, EPC 1973) allowed a divisional application to give rise to a right of priority with effects going back to the date of filing of the initial application.
However, in T 15/01 (OJ 2006, 153) the board pointed out that, with respect to the issue of exhaustion of priority, the wording of Art. 87(1) EPC 1973 appeared to be open to different interpretations. Since the EPC constituted a special agreement within the meaning of Art. 19 of the Paris Convention, this provision was not intended to contravene the basic priority principles of this Convention. The Paris Convention in its present version explicitly recognised the possibility of claiming multiple and partial priorities and guaranteed the right to divide patent applications while preserving the benefit of the right of priority for the divisional application as well (principles also recognised in Art. 76(1), second sentence, EPC 1973 and Art. 88(2) and (3) EPC 1973). The board considered that the priority provisions of the Paris Convention had to be construed in a manner which ensured that the general purpose they served, namely to assist the applicant in obtaining international protection for his invention, was fulfilled as far as possible. The board also examined the circumstances under which the issue of exhaustion might arise (splitting up of the subject-matter of the priority application to avoid non-unity objections; filing of a deficient subsequent application and remedying it by means of a second filing; combination of the originally disclosed subject-matter with further improvements and additional embodiments developed during the priority period) and analysed the interests involved. It concluded that the same priority right might be validly claimed in more than one European patent application; there was no exhaustion of priority rights. In T 5/05 the board again confirmed that neither the Convention nor the Paris Convention contained any indication that the right of priority constituted an exception which therefore had to be interpreted narrowly and thus allowed the right of priority to be exercised only once for one contracting state. These decisions were followed in T 1562/06.