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Prohibition on Double Patenting at the EPO Confirmed by Enlarged Board of Appeal in Decision G4/19

By Michael Ford, Partner

The Enlarged Board of Appeal has confirmed in decision G4/19 that there is a general prohibition on double patenting at the EPO. This means that a European patent application can be rejected if it claims the same subject-matter as a European patent which has been granted to the same applicant and does not form part of the state of the art. The prohibition applies irrespective of whether the application concerned

a) was filed on the same date as, or

b) is an earlier application or a divisional application in respect of, or

c) claims the same priority as,

the European patent application which led to the granted European patent.

In reaching its decision, the Enlarged Board assessed the possible legal basis for a prohibition on double patenting at the EPO, which had been contested by the appellants in referring case T 318/14. The European Patent Convention does not contain any explicit references to double patenting, but the EPO has thus far operated on the understanding that such a prohibition does exist. The Enlarged Board has now confirmed that Article 125 EPC, which enables the EPO to take into account the principles of procedural law generally recognised in the EPC Contracting States, provides a legal basis for the prohibition when interpreted in line with the intentions of the various Contracting States when setting up the EPC.

The decision of the Enlarged Board was not unexpected, particularly as regards situations (a) and (b) where two European patent applications were filed on the same day or where one application is an earlier or divisional application of the other. The Enlarged Board has previously accepted that an applicant has no legitimate interest in the grant of a second patent for the same subject-matter if a patent has already been granted to the same applicant for that subject-matter.

However, some applicants may be disappointed by the decision as regards situation (c), i.e. when one European patent application claims priority from another. When a second, later-filed European patent application claims priority from a first, earlier-filed European patent application, the second application is treated as having been filed on the same date (known as the ‘priority date’) as the first application for the purpose of assessing patentability (e.g. novelty and inventive step). However, the maximum term of a patent is calculated based on its individual filing date and not the claimed priority date. There was therefore an argument that an applicant could have a legitimate interest in obtaining a second patent with a later filing date (but the same priority date) to achieve longer-lasting protection for the same invention. The Enlarged Board of Appeal, however, considers that the prohibition on double patenting was intended to be general in nature and therefore outweighs any interest in obtaining longer protection.

Positively, the decision confirms that the scope of the double patenting prohibition in Europe is narrow; it only applies where the two patents have the same applicants and claim the same subject-matter. The EPO does not raise double patenting objections where the claim scope is merely partially overlapping, including where the claims of one patent fully encompass those of another.

The prohibition also only applies to conflicting European patents. The EPO will not refuse an application simply because it claims the same subject-matter as a priority-establishing patent application filed at a national intellectual property office.

This is for general information only and does not constitute legal advice. Should you require advice on this or any other topic then please contact or your usual Haseltine Lake Kempner advisor.