Double patenting at the European Patent Office

September 2021

Double patenting at the European Patent Office

Double patenting relates to a situation where two patents are granted to the same proprietor in the same country for a single invention. There is no explicit prohibition of double patenting in the European Patent Convention (EPC). However, the EPO have taken account of principals of procedural law generally recognised in the contracting states. These principles are based on the notion that a proprietor has no legitimate interest in two patents claiming the same subject matter. Under long-standing EPO practice, this is likely only to be an issue if the claims of the two patents are identical in scope (and any overlapping designations are not withdrawn).

Double patenting considerations apply to three combinations of European applications by the same applicant:

1. Two applications filed on the same day.

2. Parent and divisional applications.

3. An application and its priority application.

The Enlarged Board of Appeal have recently considered the EPO’s approach to double patenting in G4/19. The question arose as to whether a European patent application can be refused if it claims the same subject matter as another European patent granted to the same applicant under these situations. If so, what are the conditions for such a refusal? What may represent a “legitimate interest” for double patenting?

The G4/19 Decision

The case in G4/19 relates to the specific situation where both an application and its priority application are pursued to grant. European application (EP2) was filed on 7 May 2010 and claimed priority to an earlier European application (EP1) filed on 11 May 2009. Under EPO practice, the filing date (not priority date) is relevant for calculating the maximum expiry date of the European patent. The maximum term of expiry of EP1 is May 2029. However, the maximum term of expiry of EP2 is May 2030. Does this additional year’s patent term represent a legitimate interest for double patenting?

The Enlarged Board of Appeal have recently endorsed the existing approach of the EPO [1]. The decision confirms that the prohibition of double patenting applies to applications directed to the same subject matter by the same applicant, regardless of whether they are filed on the same day, are parent and divisional or are applications claiming the same priority.

The prohibition of double patenting applies regardless of whether there is any legitimate interest in a second patent (such as an additional year’s patent term). However, the Enlarged Board confirm that the prohibition only applies where the application under examination and the patent already granted claim identical subject matter, are by the same applicant and designate the same states.

Unresolved issues

It was hoped the Enlarged Board of Appeal may provide some additional clarity in the law with respect to what is meant by the “same applicant” or what may constitute the “same subject matter” between patent claims. However, these issues were not addressed by the Enlarged Board of Appeal so will likely remain contentious in the future.

For example, it remains unclear if the prohibition on double patenting applies in situations where there are multiple applicants, but only one applicant in common between the two applications. Similarly, it remains unclear if the prohibition applies if rights are assigned to a different applicant (e.g., a subsidiary company).

In practice, it is common for an applicant to seek to quickly obtain a first patent with claims directed to a narrow embodiment and pursue the general teaching in a divisional application with a broader scope of claims. Under the current EPO Guidelines, no double patenting issues arise if the scope of claims clearly differs [2]. However, more complicated situations may arise where the language of the claims is non-identical but covers essentially the same embodiment (e.g., leading to so-called “patent thickets” of overlapping subject matter).

In such scenarios, it may still be argued by the Applicant that the double patenting prohibition does not apply because the subject matters are “non-identical”. This may continue to lead to arguments with Examiners during prosecution of European patent applications. However, the Enlarged Board of Appeal confirm in G4/19 that double patenting cannot be raised by any third party in any opposition against a granted patent.

If you would like any further information, please do not hesitate to contact us at docketing@secerna.co.uk.

[1] link to full decision

[2] https://www.epo.org/law-practice/legal-texts/html/guidelines/e/g_iv_5_4.htm

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