On 16 October 2013, Squire Sanders (US) LLP co-hosted a webinar with ZBM Patents & Trademarks regarding strategic considerations for claiming priority rights and filing divisional applications in Europe, called “Poisonous Priorities and Toxic Divisional Patent Applications in Europe.”  Cristina Lopes Margarido, patent examiner at the European Patent Office, and Mathieu de Rooij, partner at ZBM, gave an interesting presentation on claiming priority rights for European patent applications and how priority applications or divisional applications can come back to bite the applicant.

European patent law recognizes three transferable patent rights with regard to patent applications: (1) the right to be granted a patent, (2) the right to file a patent application and (3) the right to claim priority to a patent application. The basic rule in Europe is the Applicant for patent listed on a European patent application, or PCT international patent application designating Europe, must hold the right to file and the right to claim priority at the time the patent application is filed. If the Applicant for patent does not hold these rights at the time of filing, the priority claim may be improper and any intervening prior art, including the Applicant’s own disclosures, becomes available to invalidate the claims of the European application or granted patent. The best practice for US patent practitioners is to make sure assignments of the patent rights to the Applicant are in place before the European patent, or PCT international patent application designating Europe, is filed.

Mr. Rooij continued the webinar with a discussion of how, under certain circumstances, later published European divisional patent applications can become prior art to, and invalidate, their parent European patent applications. According to Mr. Rooij, the scenario most often arises when the claims of the divisional application have an earlier priority date than the claims of the parent application.  A toxic divisional can then arise when the claims in the parent application are broad and the claims in the divisional application are narrow. As the issues involved in assessing the potential for a poisonous divisional application are complex, best practice for US patent practitioners is to carefully consider the ramifications of filing a divisional application in Europe in close consultation with European counsel.

This webinar is part of an on-going series giving participants direct access to European patent examiners and European patent counsel.  A recording of the Poisonous Priorities and Toxic Divisionals webinar is available on the Squire Sanders website.