  A technical board of appeal of the EPO has recently referred questions concerning partial priority to the Enlarged Board of Appeal as case G1/15.I. Context of the referral Decision G2/98, relating to the interpretation of the notion of “same invention” in Article 87(1) EPC, mentioned that the use of a generic term or formula in a claim for which multiple priorities are claimed in accordance with Article 88(2), second sentence, EPC is acceptable under Articles 87(1) and 88(3) EPC, provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters.However, the criterion of “giving rise to the claiming of a limited number of clearly defined alternative subject-matters” spelt out by G2/98 has not been interpreted uniformly by the Boards of Appeal of the European Patent Office.Indeed, in some decisions (see e.g. T184/06, T 2311/09 or T476/09), it was considered that a generic claim directed to subject-matter defined by one or more generic expressions, such as a chemical formula, a continuous range of numerical values or a functional definition, which encompassed, without spelling them out, alternative subject-matters having all the features of claim 1, could not benefit from the partial priority of a prior application disclosing only specific embodiments falling within the scope of claim 1, as the claim did not expressly identify separate alternatives. For these reasons, priority was denied to claim 1 as a whole.On the contrary, in other decisions (see e.g. T1222/11 or T571/10), it was considered that, even if a generic claim did not explicitly identify separate alternatives, it could be intellectually decomposed into two alternatives, the first one being the subject-matter disclosed in the priority document and the second one corresponding to the remaining subject-matter of claim 1. In this case, the first alternative would enjoy the priority while the second one would not.   II. Questions referred to the Enlarged Board of Appeal In view of this situation, in its decision T0557/13, the competent Board of Appeal referred the following questions to the Enlarged Board of Appeal:1. Where a claim of a European patent application or patent encompasses alternative subject-matters by virtue of one or more generic expressions or otherwise (generic "OR"-claim), may entitlement to partial priority be refused under the EPC for that claim in respect of alternative subject-matter disclosed (in an enabling manner) for the first time, directly, or at least implicitly, and unambiguously, in the priority document?2. If the answer is yes, subject to certain conditions, is the proviso "provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters" in point 6.7 of G 2/98 to be taken as the legal test for assessing entitlement to partial priority for a generic "OR" claim?3. If the answer to question 2 is yes, how are the criteria "limited number" and "clearly defined alternative subject-matters" to be interpreted and applied?4. If the answer to question 2 is no, how is entitlement to partial priority to be assessed for a generic "OR"-claim?   5. If an affirmative answer is given to question 1, may subject-matter disclosed in a parent or divisional application of a European patent application be cited as state of the art under Article 54(3) EPC against subject-matter disclosed in the priority document and encompassed as an alternative in a generic "OR"-claim of the said European patent application or of the patent granted thereon?In this context, a “generic ‘OR’-claim” is to be understood as a claim directed to subject-matter defined by one or more generic expressions, such as a chemical formula, a continuous range of numerical values or a functional definition. Such a claim encompasses, without spelling them out, alternative subject-matters having all the features of claim 1.III. The question of partial priority has a high relevance in practice In particular, if the claims of a subsequent application are broader than the disclosure of the priority application, it is important to know whether the subsequent application might benefit at least partially from the priority of the priority application or whether the priority application might be novelty-destroying for the subsequent application and should therefore be withdrawn before publication.Furthermore, the EPO recently rendered several decisions in which a divisional application was considered novelty-destroying against its own parent application due to the fact that the parent application contained generic claims for which partial priority was not recognised, while the divisional application disclosed specific examples falling within the recited range and benefiting from the priority of the prior application. It would be important, for reasons of legal certainty, that such cases are ruled in the same manner by all Boards of Appeal.We will keep you informed about any developments regarding this case.If you have any questions concerning this newsletter, please contact Anne Francastel. 