Priority a Priority for the EPO EBA this Week – G1/15

June 2016

This week the EPO Enlarged Board of Appeal (EBA) will hear the case G 1/15, a referral under Art 112(1)(a) EPC by the Technical Board of Appeal T 0557/13 regarding patent number EP0921183 known as the “Partial priority” case.  “Partial Priority” is a controversial  subject – almost 40 amicus curiae briefs  giving view points on the case submitted by a variety of IP firms, IP bodies and industry have been filed on the case.  

A number of older, but more common EPO decisions, as well as at least two judgments of the English courts, have followed a strict interpretation of “clearly defined alternative subject matters”.  However, more recent decisions have supported a broader interpretation. Due to these diverging conclusions on the same question of how to interpret the condition referred to in historic EPO case law (G2/98), the matter has now been referred to the EPO EBA.  For patentees, and practitioners, who can experience little uniformity in the approach of the EPO’s Technical Boards of Appeal with regard to the issue of partial priorities the decision is eagerly awaited.  It seems unlikely the EBA will give their decision straight away but we will keep you posted as news arises.


 The specific questions to be addressed by the EBA (see the decision in T0557/13) are:

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?

The present controversy arises from divergent interpretations of the meaning of “clearly defined alternative subject-matters,” in EPO decision G 2/98.

Under the EPC, a claim in a European patent application may be allowed multiple priority dates. A feature in a claim is only entitled to an earlier priority date if both the priority document and the later application relate to “the same invention”.  As a simple example, suppose a first application 1 is filed and discloses and claims feature A. A subsequent application 2 is then filed, claiming priority from application 1. Application 2 discloses and claims new feature B, as an alternative to feature A. In that scenario, where features “A” and “B” are clearly individualised in the claim, it is relatively straight forward to identify which portion of the claim is entitled to which priority date.

However, consider now that instead of claiming “A or B”, application (2) claims “C”, where C is a generic group within which both A and B might fall. In that case, it is not so straightforward to identify which parts of the claims are entitled to the priority date of the first application. In G2/98, it was decided that a generic claim like this could be entitled to multiple priorities “provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters.”

A first, strict interpretation of “clearly defined alternative subject matters” essentially requires that the “clearly defined alternative subject-matters” must be separately identified in the claim.  So in the first example above, claims to “C” would not be entitled to the priority date of the first application claiming A, since A is not separately identified from B. Consequently, application 1 may therefore count as prior art against application 2. This is an example of “poisonous priority”, because the priority application 1 discloses subject matter A, which is a special case of generic subject matter C, and therefore anticipates subject matter C.

A second, broader interpretation instead argues that it is sufficient that the “alternative subject-matters” be identified implicitly without needing to be specified as such within the claim.  So, reusing the A/B/C subject matter example from above, application 2 would be entitled to the priority claim of application 1 in respect of matter A, and “poisonous priority” would not be an issue because application 1 only discloses matter A.