The recent case law of the European Patent Office (EPO) on the circumstances in which it is possible for a European application to claim a partial priority from an earlier application, e.g. when the subject-matter claimed in the later European application partly differs from, in that it partly extends beyond, the one disclosed in the earlier application, has been quite divided. In fact, certain EPO decisions allowed for such partial priority to be claimed in view of the partially overlapping subject-matter, while other decisions denied the possibility of claiming any priority in view of the subject-matter claimed in the European application but not disclosed in any part of the priority application.

Of course, a situation in which the claims of a European application also relate to subject-matter not already disclosed in the priority application is quite common. In fact, during the priority year it is quite common that inventors will continue their research and thus also achieve results, e.g. in the form of embodiments, not already identified at the time of filing of the priority application, so that the claims of the European application will also relate to such additional embodiments.

One of the EPO Boards of Appeal has now acknowledged the existence of such divergent case law and has thus referred certain questions to the EPO’s highest instance, i.e. the Enlarged Board of Appeal. The decision to refer the questions to the EPO is dated July 17, 2015. It is now pending at the Enlarged Board of Appeal as referral number G 1/15.

The following are the questions referred to the EPO Enlarged Board of Appeal for decision:

“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 … 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?”

Thus, the referral turns around the main question whether, where a European claim encompasses alternative subject-matters by virtue of one or more generic expressions or otherwise, entitlement to to partial priority may be refused by the EPO in respect of that part of the subject-matter which is already disclosed in the priority document.

It will be essential to closely monitor the development of this referral, as the Enlarged Board of Appeal’s answers to the referred will surely have a great impact on many cases pending before the EPO, be they pending European applications or opposed European patents.


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