You are here: Home > News > Taking the sting out of poisonous divisionals

Taking the sting out of poisonous divisionals

30 November 2016

The Enlarged Board of Appeal (EBoA) of the European Patent Office (EPO) has today indicated in case G1/15 that the so-called issue of “poisonous divisionals” has been put to rest.  The background context to this is that there had been concerns that it might be legally possible for a divisional patent application to be held to anticipate its parent application and consequently render it invalid.

This case follows on from the well documented case of Nestec SA v Dualit Ltd in the UK, various decisions of the EPO Technical Boards of Appeal and the prominent EBoA case of G2/98.

Although the full decision of the EBoA has not yet been issued, its order states that:

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 language of the order is not entirely transparent, but it certainly appears to suggest that the previously feared scenario of being prevented patent protection by one’s own disclosure(s) within the same patent family are no more.

This will come as welcome news to Applicants, since it seemingly removes the possibility of inadvertently prejudicing oneself from patent protection due to actions taken during the application process.

Further clarification can be expected when the full decision is issued in due course.


If you require further information on anything covered in this briefing, please contact Jon Elsworth (; +44 207 940 3600) or your usual contact at the firm. This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Withers & Rogers LLP, November 2016