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New Procedure For Accelerating EPO Oppositions Provides Early Legal Certainty When There Is Ongoing Parallel UPC or National Litigation

Mar 8, 2024

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    Michael Nielsen

    I work as a European & UK patent attorney at Berggren, helping clients to secure and protect the rights for their inventions across Europe. I enjoy taking the complicated field of European patent law and turning it into concrete, relevant advice for our clients and their businesses.


    The European Patent Office (EPO) offers a post-grant procedure for challenging the validity of a European patent, known as opposition. An opposition can be filed by any person within nine months from the publication of the grant of the patent. The opposition proceedings are conducted by an opposition division, which consists of three technically qualified examiners. The opposition division may revoke the patent, maintain it in amended form, or reject the opposition.

    Parallel litigation

    Sometimes, a European patent may also be involved in a parallel litigation before the Unified Patent Court or a national court of a contracting state. This may happen, for example, if the patent owner sues an alleged infringer for patent infringement, or if a third party seeks a declaration of non-infringement or invalidity of the patent. In such cases, the outcome of the opposition proceedings may have a significant impact on the litigation, as the validity of the patent is a central issue in both proceedings.

    Acceleration of opposition proceedings

    EPO opposition proceedings may take several years to reach a decision, depending on the complexity of the case and the workload of the opposition division. However, in cases where there is a parallel litigation, the parties may request acceleration of the opposition proceedings, in order to avoid unnecessary costs and delays.

    Following a notice issued late in 2023, the EPO recently issued guidance on accelerated processing of oppositions, which sets out the process and timeline for accelerated oppositions. The key points are:

    • The EPO will accelerate processing of opposition proceedings if it is informed by the Unified Patent Court or a national court (or other competent authority) that an infringement or revocation action relating to a European patent has been filed.
    • Alternatively, a party to the parallel opposition proceedings may request accelerated processing at any time.
    • Where opposition proceedings are accelerated, the EPO will “make every effort” to issue the next procedural action within three months of receipt of notice of the parallel action.
    • A summons to oral proceedings will be issued within two months of receipt of the notice of the parallel action or the proprietor's reply to the statement of opposition, whichever comes later. The date of the oral proceedings will be as early as possible.

    This accelerated procedure is effective immediately and also applies to oppositions that have already been filed.


    In cases where an opposition is not accelerated, the EPO’s target is for a decision to be reached in opposition proceedings within 15 months of the notice of opposition being filed. In practice, the median processing time is around 19 months. Given the 9-month period for oppositions to be filed, this means that more than half of EPO oppositions remain undecided two years after the grant of a European patent.

    This new acceleration of EPO opposition proceedings is a welcome change in the EPO’s practice, especially in the context of litigation in the Unified Patent Court, which has a target to reach a final decision on the merits of a case within 12 months. Aggressive acceleration from the EPO ensures that earlier legal certainty can be provided and serves the interests of all parties involved in the proceedings.

    Furthermore, rapidly concluded EPO opposition proceedings may have a Markman-like effect on UPC proceedings, solidifying a particular claim interpretation before the UPC. Given that the European Patent Convention is the relevant law for validity in both EPO opposition proceedings and UPC revocation proceedings, it would be undesirable if the UPC were to regularly diverge from an interpretation of claims confirmed by the EPO.

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