5 Jul 2017 | Patents and Utility Models

G1 / 15 – the antidote against “poisonous priority”

In its latest decision, G1 / 15, the enlarged Board of Appeal of the European Patent Office ended the possibility of “poisonous priority”. According to this decision, under the EPC, entitlement to partial priority may not be refused for a claim encompassing alternative subject-matter by virtue of one or more generic expressions or otherwise (generic “OR”-claim), provided that said alternative subject-matter has been disclosed for the first time, directly, or at least implicitly, unambiguously and in an enabling manner in the priority document. No other substantive conditions or limitation apply in this respect.

According to the European Patent Convention (EPC), the applicant of a European patent application may claim priority of a former application disclosing the same invention (Art. 87 EPC). In addition, Art. 88(2) EPC stipulates that multiple priorities may be claimed for any one claim. Furthermore, it is laid down in Art. 88(3) EPC that if one or more priorities are claimed in respect of a European patent application, the right of priority shall cover only those elements of the European patent application which are included in the application(s) whose priority is / are claimed. That is, Art. 88(3) EPC confirms that a claim of a European patent application may cover subject matter going beyond what was disclosed in a priority application, and may then only be partially entitled to priority. Such a claim may thus in principle be split according to subject-matter having different effective dates.

These rules did not cause any major problems as long as different domains have explicitly been mentioned as alternatives (for example by a wording such as “device characterized by having element 1 or element 2”). However, some technical Boards of Appeal denied the validity of the partial priority when the subject-matters forming partial priority domains were not addressed explicitly in the claim, but were only conceptually identifiable within the scope of a generic claim term by reference to a narrower disclosure found in the priority application and merely encompassed within the scope of a broader generic claim term employed in the later filing that claims priority. A very typical example for such a situation is the broadening of a chemical formula or of a numerical range. Such a generic “or“-claim encompasses, without spelling them out, alternative subject-matters having all the features of the claim.

In the decision underlying the present case, T 557 / 13, granted claim 1 encompassed a generalization of a more specific disclosure of the priority application. Although the patent met the requirements as to original disclosure, it did not enjoy the priority date of the parent application, which thus, was prior art under Art. 54(3) EPC. Consequently, the subject-matter of claim 1 as granted lacked novelty (under Art. 54(3) EPC) in view of the very specific embodiment of one of the examples disclosed identically in the parent application and in the priority document. The embodiment described in the parent application was held to be “entitled to the claimed priority date”, whereas granted claim 1 (of the divisional application) was held to be “only entitled to the filing date of the parent application”. Similar decisions have been made in the past in comparable situations (see, for example, T 1127 / 00, T 2311 / 09, T 184 / 06 or T 1443 / 05). With the present decision, G1 / 15 a respective danger is now adverted for the future.


Partial priority may no longer be refused for a claim encompassing alternative subject-matter by virtue of generic expressions if the priority document discloses part of the subject-matter in a way that could be novelty destroying. In such a case, the claim is conceptually divided into two parts, the first corresponding to the subject-matter directly and unambiguously disclosed in the priority document (for which partial priority is validly claimed), and the remainder not enjoying this priority.