Priority Date Assessment under EPC (Part 1)

Nearly ten years ago, an eminent member of an Appeal Board in the EPO opened a particular issue at oral proceedings with the words “The problem the EPO has with priority…”. It was certainly a taxing issue then, and it is still a taxing issue now.

One of the two tests for attribution of priority in G0002/98 is the same as that which controls added matter, and as time has passed it has grown closer to those legal origins in its implementation. The other test, less well-formed, has been implemented differently by different EPO tribunals – but creating a semi-consensus amoungst the majority of appeal boards; that is now challenged by an alternative approach which, if adopted, will change many future outcomes, and probably for the better, but only after a period of uncertainty.

And priority in Europe is not just taxing, but also very relevant to commercial outcomes. There is one context which makes it especially so: a large proportion of EPC patent applications originate in the PCT environment and, created by practitioners outside Europe whose grasp of the above picture is necessarily limited, follow strategies which can lock in attributes which fit poorly with the EPC priority system. That’s an issue made worse, although by no means created, by recently emerging IP risks such as Poisonous Divisions and Poisonous Priority Documents. Hopefully, this paper will catalyse debate and aid communication in a way that ameliorates that issue.

0.     Introduction and overview

0.1    Priority entitlement is at the core of best patent practise, capable of determining “life and death” decisions in private patent validity disputes as well as in the more extreme of patent prosecution contexts. Whilst there is literature highlighting individual EPO Appeal Board decisions within this overall theatre, less than might be expected has been written on priority date assessment in the round using Enlarged Board of Appeal Decision G0002/98 as the starting point.

0.2    Priority is seldom a straightforward matter for patent proprietors where the technology concerned, or perhaps the proprietor’s understanding of it, grows within the priority year after first filing and leads to specification changes which threaten the originally established priority date.

0.3    Priority is equally a tough issue for tribunals and, as this paper will show, appellate decisions of the EPO have been an imperfect source of guidance for patent applicants and patentees. Indeed, a definitive position on multiple priorities is still lacking 15 years after the presidential referral that led to the landmark Enlarged Board of Appeal Decision G0002/98. As one of a handful of concepts that are absolutely fundamental to the patent system, it is remarkable that any significant aspect of priority should still await
final resolution after such a lengthy gestation period.

View the document here
Back to Publications