European Patent Office (EPO)’s Board of Appeal issues decision G1/15 on partial priorities, defusing concerns over ‘poisonous’ and ‘toxic’ European Patent (EP) divisionals.

The Enlarged Board’s decision clarifies that a partial priority for a claim may not be refused on the grounds that the claim includes subject matter that has been directly (or implicitly) disclosed in the priority application. This is good news for applicants filing a European Patent application as it should allow them to broaden disclosure in the priority application without worrying about the possibility of poisonous divisionals.

‘Poisonous’ divisionals are said to occur where the claim of a parent application is open to being challenged for lack of novelty due to subject matter described in its own divisional application. In other words, the system risked invalidating one or more of an applicant’s cases because of subject matter contained in their other cases. Applicants were faced with tough and complex decisions as a result (e.g. not filing a divisional application in case it invalidated the parent application). The outcome of G1/15 very much looks like those fears can now be laid to rest.

The Board explained: Under the [European Patent Convention], 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.”