How to Claim Patent Priority? A Comprehensive Guide

Applicable text

Although similar, the rules applicable to priority for standard European applications are those of the EPC (A87 EPC) and not those of the Paris Convention (A4 Paris Convention) (J15/80).

For Euro-PCT applications, the PCT must be applied (A150(2) EPC), which explicitly refers to the Paris Convention (A8.2.a PCT) or more precisely to its latest version (i.e., the Stockholm Act).

Claims and priority correction

To learn how to claim and correct a priority, please refer to: filing requirements.

Substantive conditions to be met

Persons who may claim priority

Any person

In principle, any person may claim priority, whether or not that person is domiciled in a member state.

Limitation

However, this does not mean that there are no conditions for claiming priority.

The only persons who may claim priority are (A87(1) EPC):

the applicant of the earlier application;
their successor in title.

It is worth noting that for a long time, the EPO required additional conditions such as a written assignment, identity of applicants, an assignment prior to the priority claim, etc. However, the decisions of the Enlarged Board of Appeal G1/22 and G2/22 have reversed this trend: the right to claim priority is presumed to exist as soon as the formal conditions for claiming priority are met.

The presumption is rebuttable, with the burden of proof resting on the party contesting the validity of the priority, but that party must submit serious factual evidence.

Special case of a priority assignment

Principle

It may happen that a person assigns the initial application along with its priority right (e.g., filing of a US provisional application by inventors, T407/15).

Law applicable to the assignment

To assess the validity of the assignment, reference must be made to the national law applicable to the assignment (and not the law of the country of filing of the initial application) (T0517/14): however, the EPO case law has not established the rule for determining this applicable law (good luck with that).

In particular, there is no reason for A72 EPC (which prescribes a written assignment for a patent application) to apply to an assignment of the priority right (T0517/14): the assignment may well be oral if the national law permits it.

Thus, the specific case must be analyzed to determine the applicable law. For example, this may be:

the law of the employment contract for an assignment between an employee and an employer;
the law chosen by the parties at the time of signing the assignment agreement.

Even more specific case: a partial assignment of the right of priority

It appears entirely possible to assign only part of the right of priority (T969/14).

Thus, if an application contains two inventions (i.e., A and B), it is possible to assign A while retaining the benefit of B for oneself.

If, unfortunately, the assignee files a patent application covering A and a portion of B, they will indeed have the priority date for A but only the filing date for B (T969/14).

Applications allowing a priority claim

Nature of applications

The A87(1) EPC specifies that the application may be:

a patent application,
a utility model application, or
a utility certificate application.

Industrial design applications (Geschmacksmuster) are excluded from this right (G3/93, J15/80, Guidelines A-III 6.1).

Origins of applications

The priority application must have been filed:

in a State party to the Paris Convention (A87(1)(a) EPC);
in a WTO member (A87(1)(a) EPC, since December 13, 2007, noting that a WTO member is not necessarily a State);
before the EPO (« in or for, » A87(1) EPC) and A87(2) EPC, since the EPC is a bilateral agreement (Guidelines A-III 6.2).

Although it is possible to provide for certain agreements with countries not complying with these rules to extend this right (A87(5) EPC), no communication has been made to date (Guidelines A-III 6.2).

Here is a table of member states with their accession date: