Dr. Hans Weickmann

Guideline for Validly Claiming Priorities


Losing priority may cause the loss of a protective right. In the following, we provide guidelines to prevent priority being lost for mere formal reasons.

by Dr. Hans Weickmann, Weickmann & Weickmann

According to Article 87 EPC, any person who has duly filed an application for patent, or his successor in title, shall enjoy, for the purpose of filing a European patent application in respect of the same invention, a right of priority during a period of twelve months from the date of filing of the first application.

There are four requirements to fulfil: 

a)         period of 12 months

b)         same applicant

c)         first application

d)         same invention

The right of priority has the effect that the date of priority shall count as the date of filing of the European patent application for assessing the relevant prior art (Article 89 EPC).

As a general rule, the division at the EPO does not make any investigation as to the validity of a right to priority. However, the priority right assumes importance if prior art has to be taken into account which has been made available to the public on or after the priority date claimed and before the date of filing (“intermediate document”).

Valuable patent applications and patents have been lost because some formal aspects relating to the “same applicant” (b) have not been met. 

For a claimed priority to be valid, the applicant of a subsequent application claiming priority from an earlier application (priority application) who is not the person who filed the priority application must, when the subsequent application is filed, be that person's successor in title in respect of the priority application or of the right to claim priority. A succession in title that occurs after the filing date of the subsequent application is not sufficient to comply with the requirements of Article 87(1) EPC (T577/11).

Clearly, the succession in title has to be proven by the party claiming a right to priority (see J19/87). T62/05 required that the succession is proven in written form and has to be confirmed by signatures by or on behalf of both parties to the transaction. However, more recent decisions state that a formal transfer is not necessarily required, but the determination of the requirements of transfer of the priority right is a matter of national law (T517/14). Which national law is applicable is discussed in T1201/14.

In case of two or more applicants, it is to be observed that the priority right belongs simultaneously and jointly to all applicants who thus constitute a legal unity, unless one of them decides to transfer to the other applicant, who then becomes his successor in title (T788/05). As discussed above, such succession has to take place before the filing of the subsequent application. 

In sum, there are two possibilities to fulfil the “same applicant” requirement b):

i). assure that all rights to priority have been validly transferred to at least one of the applicants of
    the subsequent application before filing the same. Ideally, the transfer of priority right is in
    written form, being signed by assignor and assignee,

      ii). if i) cannot be guaranteed before filing a subsequent application within the respective time
          limit a), a subsequent application shall be filed in the (identical) name of each and every
          applicant of the priority application(s). The applicantship of the subsequent application may be
          regulated after filing the same – however, without the risk of losing the priority right for mere
          formal reasons.


Observing some simple rules as to the “same applicant” requirement helps to increase the chances of a valid priority right. Rest assured that the other requirements c) and d) are much harder to fulfil! 



Dr. Hans Weickmann, Dipl. -Chem., Dr. rer. nat., Patent Attorney, Partner
Weickmann & Weickmann, Patent- und Rechtsanwälte PartmbB, Munich
Tel.: +49 (89) 455630 | E-Mail: hweickmann@weickmann.de



<- Back to: News