Priority Pitfalls to Avoid at the EPO The recent consolidated referral to the Enlarged Board of Appeal at the European Patent Office (EPO) (G1/22 and G2/22) will mean another close look at the rules that must be followed for a patent priority claim to be considered valid in Europe. A brief report on the subject of that referral can be found here, but it is likely to be some time before the Enlarged Board’s answers to the referred questions are published. In the meantime, the case is a reminder of how strict the EPO can be when assessing a priority claim, and how easy it can be to inadvertently lose the benefit of priority. The following provides some important points to consider, and errors to avoid, when the intention is, or may be, to rely on a priority claim in a patent or application at the EPO.
Fixed at the filing date Article 4A(1) of the Paris Convention is enacted as Article 87(1) in the European Patent Convention (EPC), and provides some bare bones requirements for a valid priority claim. It is important to remember that these more formal requirements are generally assessed as of the filing date of the subsequent (i.e. priority claiming) European application. If it is found during prosecution or opposition proceedings at the EPO, for example, that the priority claim was not validly made because the applicant was not the same as, nor the successor in title to, the applicant for the priority application on the filing date of the European application (see below), then there is often very little, if anything, that can be done to rectify the situation and recover the priority claim. It is therefore vital to make a correct priority claim on the filing date. Particular pitfalls can arise when the European application or patent is derived from an International application. In such cases, the International application might be filed by an applicant or attorney from a jurisdiction other than Europe, who might be balancing many other concerns and so have given only
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minimal thought to the possible resultant European application. However, if the requirements for priority are not met when filing the International application, it could be fatal to the eventual European application or patent. To rectify this, it might be possible to request a correction of the original application documents, but the requirements for a correction can be arduous. A correction is generally required rather than an amendment, because a correction is considered to have effect from the date on which the error was made (“ex tunc”), i.e. the date on which the subsequent application was filed, whereas an amendment is considered to have effect from the date on which the request for the amendment was accepted (“ex nunc”).
Check the applicant details The priority right to an earlier patent application may only be enjoyed by the applicant of the earlier application or their successor in title. This is one of the strict priority requirements at the EPO. If the applicant of the subsequent European, priority claiming, application is not the same as the applicant for the priority application, then the applicant of the subsequent application must be ready to explain how they have become successor in title for the priority rights. In such cases, the transfer of the priority right can have occurred by any legal means, according to the relevant local law applicable to the priority rights, but if the priority claim is challenged then the onus will
be on the owner of the subsequent application or patent to show that the transfer had occurred before the subsequent application was filed. In addition, if there is more than one applicant for the priority application, then the priority rights of all the applicants must be accounted for. In other words, either all the same applicants must be listed on the subsequent application as on the priority application when the subsequent application is filed, or the owners of the subsequent application or patent must be able to show how the priority rights of any applicants “missing” from the subsequent application were transferred to an applicant that was listed on the subsequent application. This can be a particular pitfall when emphasis is placed on indicating correct (or, at least, intended) ownership of the invention rather than the priority rights. For example, there may have been a reassessment of the inventors for the invention, or a parent company may have decided that a different subsidiary company should have ownership of the invention, such that it is felt that different applicants have ownership of the invention in the subsequent application. However, it must be remembered that priority right is a completely separate and severable right to ownership of the invention described in the patent. A priority right may be obtained simply by being listed as an applicant on an application, whereas assessment of the ownership of the invention defined in the priority (and subsequent) application will be determined by inventor contributions
