News & Resources


An End to Poisonous Divisionals at the EPO

EPO: Enlarged Board of Appeal Decision G1/15

The Enlarged Board of Appeal (EBA) released its full decision on G1/15 on 1 February 2017, which can be found here: This decision should end the possibility of a parent application being found not to be entitled to priority and hence to lack novelty over a divisional application.


There have been diverging decisions regarding whether partial priority should be allowed for a European application that claims an invention more broadly than that disclosed by a priority application.

A strict test was provided in G2/98, when the EBA set out the proviso that partial priority is allowed under art. 88(2) EPC only if the use of a generic term “gives rise to the claiming of a limited number of clearly defined alternative subject-matters”.

However, over the past few years, there have been diverging decisions regarding the interpretation of the G2/98 test. Some cases took the G2/98 literally, leading to refusal of partial priority (see section 2.2 of the G1/15 Decision in the link above). As a consequence, some applications have been refused priority and have subsequently found to lack novelty over subsequently filed divisional applications, which have been found to be entitled to the priority claim.

Other cases interpreted the G2/98 test more loosely to acknowledge partial priority by “conceptually” dividing the claim into the “limited number of clearly defined alternatives” (see section 2.4 of the G1/15 Decision in the link above).

The EBA has now decided what the correct interpretation of the law should be.


The first question referred to the EBA in G1/15 was phrased as follows:

“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?”

The EBA’s answer to this question was ‘no’, stating that there was no need for the substantive conditions or limitations laid out by G2/98.

The decision of the EBA outlines the reasons for its answer. Since the respondent in the case had contested the validity of partial priority (see part VII of the Summary of Facts and Submissions), the decision discusses basis for partial priority in the EPC, stating in section 5.1.2 that support for partial priority is provided in art. 88(3) EPC:

“If a claim in the later application is broader than an element disclosed in the priority document, then priority may be claimed for such element but not for all other embodiments encompassed by the claim…It is of no relevance whether one claim for which partial priority is claimed encompasses only one element disclosed in a priority document”.

In section 5.2 of the decision, the EBA emphasises that priority may not be refused “on the ground that an application claiming one or more priorities contains one or more elements that were not included” in the priority application provided there is unity of invention.

The decision goes on to state that G2/98 “cannot be construed as implying a further limitation of the right of priority”, thereby overruling G2/98’s proviso of clearly defining a limited number of alternative subject-matters”.

The Decision lays out a simple test (see section 6.4 of the Decision) for assessing whether subject-matter within a generic “OR” claim can enjoy partial priority:

  1. determine the subject matter disclosed in the priority document relevant for overcoming prior art using the EPO’s “direct and unambiguous” standard; and
  2. examine whether this subject matter is encompassed by the claim of the application or patent claiming priority.

It is hoped that G1/15 will put an end to the practice of poisonous divisionals, in which a divisional can be cited as art. 54(3) prior art against its own parent when the parent has lost its right to priority.

If you have any questions on this topic, please contact Andy Cloughley at


Article written by Emily Crizzle

Share this page:
In this section