23 February 2017

G1/15: Partial Priority at the European Patent Office

The Enlarged Board of Appeal of the European Patent Office has issued its written decision in case G1/15 relating to the issue of partial priority. In this decision the Enlarged Board held that a generic claim encompassing alternative subject matter may not be refused partial priority, provided the alternative subject matter has been directly, at least implicitly, and unambiguously disclosed in the priority document.

‘Partial priority’ refers to a situation in which only part of the subject matter encompassed by a claim is entitled to the priority date. Such a situation can occur for example by the broadening of a chemical formula, of a range of values or of chemical compositions relative to the disclosure of the priority document.

In a previous decision (G2/98), the Enlarged Board had held that partial priority was allowed for a generic term or formula in a claim ‘provided that it gives rise to the claiming of a limited number of clearly defined alternative subject matters’. Following on from this decision two diverging lines of case law had arisen with some decisions taking a generous approach to partial priority and others applying a much stricter approach. 

One illustrative example of the strict approach is that of a priority document disclosing a range of ‘0.94 to 0.99’ which had been broadened to ‘0.930 to 0.990’ in the claims of the application. In this case it was held that the claimed range represented a continuum of a numerical range of values which did not correspond to distinctive alternative embodiments. The board did not acknowledge the presence of partial priority.     

On the other hand a number of other decisions had acknowledged partial priority in comparable circumstances.

The Enlarged Board was asked to decide between these two approaches and was asked to answer the following question:

“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 Enlarged Board answered this question in the negative, stating “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 limitations apply in this respect.”

The decision also sets out a two-step test for assessing whether subject-matter in a generic “OR” – claim may benefit from partial priority:

  1. determine the subject-matter disclosed in the priority document that is relevant in respect of the prior art disclosed in the priority interval; and
  2. examine whether this subject-matter is encompassed by the claim of the application or patent claiming said priority. 

If the outcome of the second step is that the subject-matter is encompassed, then the claim is conceptually divided into two parts. The encompassed subject-matter is entitled to partial priority. The remaining subject-matter is not entitled to priority but itself gives rise to the right of priority. 

In favouring the more generous approach, G1/15 should make it much easier for a claim to benefit from partial priority and therefore reduces the risk of self-collision via so-called ‘poisonous priority’ and ‘toxic divisionals’.