In a decision on a question of law referred to it by the President of the EPO, the Enlarged Board of Appeals has decided that, notwithstanding Article 4B of the Paris Convention, publication, after the filing of the priority-founding application, of the technical content of what was contained in that application may be cited against any claim (or presumably, in view of Article 88(2) of the European Patent Convention, which permits multiple priority dates in a single claim, part of a claim) contained in the European Patent application that is not entitled to the priority date of the priority-founding application.

Thus, for example, if the European application claims an invention more broadly than is supported by the priority application or additional features are claimed in the European application which have no support in the priority application, any publication of the subject matter of that priority application that occurs before filing the European application may be used as the basis of an obviousness attack on the claims of the European application that are broader than are supported by the priority application or which are directed to specific features not disclosed in the priority application. In this context it will be recalled that, as discussed previously in our Information Letter N.S 180, the EPO's rules on whether a claim is entitled to a priority date are reasonably liberal. Even so, in cases where development work is continuing after the filing of an application that may be used to claim priority in a European application, care should be taken to ensure that no disclosure of the content of the application occurs before filing in Europe. This should avoid the risk that publication of that disclosure may be used to invalidate any claims in the European application that go beyond what is supported by the original priority-founding application.