Posted on 30/1/2024

Ink marks the spot: Signature standards in patent assignments

A recent decision of the EPO Boards of Appeal calls into question whether even qualified electronic signatures are suitable for use in assignment documents.

We previously reported, here, on a Notice of the European Patent Office (EPO) issued on 22 October 2021, which highlighted that the EPO would accept either wet ink signatures or qualified electronic signatures on assignment documents supporting the request for the transfer of a European patent application.

The requirements of qualified electronic signatures are stringent and most commonly available signature software programs are unable to generate them. Despite this, the willingness of the EPO to accept such electronic signatures was considered a positive step towards more digital working.

However, a recent decision of the EPO Boards of Appeal (BoA) (J 0005/23) now calls into question whether even qualified electronic signatures are suitable for use in assignment documents.


The appeal in question was filed by the applicant of a European patent application against a decision of the EPO Legal Division, which rejected the applicant’s request to record the transfer of the application to another party on the European Patent Register.

The applicant’s request was based on an electronic copy of an assignment agreement, which contained “text string signatures” for both the assignor and the assignee. A “text string signature” is defined as a “string of characters, preceded and followed by a forward slash (/), selected by the signatory to prove their identity and intent to sign”.

The Legal Division deemed these “text string signatures” non-compliant with the EPO’s October 2021 Notice, emphasising the requirement for an assignment document to be signed using wet ink or a qualified electronic signature.

In the applicant’s appeal to the BoA, it referenced a decision of the President of the EPO dated 14 May 2021 regarding electronic document filing, to argue that “text string signatures” should be allowable in assignment documents.

Board of Appeal’s Decision

In its decision, the BoA referred to Article 72 of the European Patent Convention (EPC), which reads:

“an assignment of a European patent application shall be made in writing and shall require the signature of the parties to the contract”.

The BoA’s decision centered on the interpretation of the term “signature” in Article 72 EPC, considering the Vienna Convention on the Law of Treaties. The Board concluded that a signature in an assignment contract must create an objectively verifiable link between the signature and the signatory. The Board stated that considering any type of text in electronic form which refers to the name of a person as a “signature” within the meaning of Article 72 EPC would be at odds with this rationale.

The BoA also stated that the decision of the President of the EPO referred to by the applicant only related to the manner in which documents may be filed in proceedings before the EPO, and not to the requirements for a valid assignment contract, meaning that the Decision was not applicable to the case at hand.

The BoA then turned its attention to the EPO’s Notice of 22 October 2021, which had deemed qualified electronic signatures acceptable in assignment documents. The Board commented that the Notice was not a legal instrument by a competent legislative body and so could not be relied on when interpreting the term “signature” in Article 72 EPC. The Board went on to state that without a different definition in the Implementing Regulations, “signature” in Article 72 EPC refers strictly to a handwritten depiction on the assignment contract. The Board thus dismissed the appeal, maintaining that, at present, electronic signatures, including qualified electronic signatures, do not comply with the formal requirements of Article 72 EPC for assignment agreements.


This case signals a departure from the EPO’s October 2021 Notice, emphasising that, at least for now, only wet ink signatures are deemed acceptable on assignment agreements for them to be recordable on the European Patent Register.

Nevertheless, the Board clarified that Article 72 EPC does not explicitly prohibit introduction of a definition for the term “signature” in the Implementing Regulations, which encompasses electronic signatures – and so, such signature forms may become allowable in future.

Until a concrete change in the law takes place, however, we strongly recommend that wet ink signatures be used on assignment documents if their recordal on the European Patent Register is intended.

If you have any questions about protecting your intellectual property get in touch to speak to one of our attorneys.

Wilson Gunn