EPO just published an important decision regarding priority right. According to this decision, the European Patent Office is competent to assess whether a party is entitled to claim priority under Article 87(1) EPC: there is a rebuttable presumption under the autonomous law of the EPC that the applicant claiming priority is entitled to claim priority. The rebuttable presumption also applies in situations where the European patent application derives from a PCT application and/or where the priority applicant(s) are not identical with the subsequent applicant(s).
In a situation where a PCT application is jointly filed by parties A and B, (i) designating party A for one or more designated States and party B for one or more other designated States, and (ii) claiming priority from an earlier patent application designating party A as the applicant, the joint filing implies an agreement between parties A and B allowing party B to rely on the priority, unless there are substantial factual indications to the contrary.
This decision changes the practice of the EPO and decrease the burden on applicants to claim priority when applicants of the priority application an EP application are not the same. It is however still advised to keep in the file an assignment of priority right when applicants of the priority application an EP application are different.