An International Guide to
Patent Case Management for Judges

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11.2.2 Opposition proceedings

The opposition procedure before the EPO is a contentious administrative procedure following the grant procedure. The relief sought by the opponent is not, as in pre-grant opposition, the refusal of the patent application but rather the revocation of the patent with retroactive effect in all designated Contracting States.13 Opposition proceedings thus allow, during a limited period, a request for the revocation of the entire European patent (i.e., encompassing all national parts) to be brought before and decided by the EPO in a centralized procedure.

Within nine months after publication of the mention that a European patent has been granted, anyone may give the EPO a notice of opposition.14 Opposition may only be filed on certain grounds – namely that:

  • the patent’s subject matter is not patentable (e.g., because the claimed subject matter is not novel, does not involve an inventive step or is excluded from patentability);

  • the patent does not disclose the invention clearly and completely enough for it to be carried out by a person skilled in the art; or

  • the patent’s subject matter extends beyond the content of the (earlier) application as filed.15

In opposition proceedings, the Opposition Division examines whether the grounds for opposition prejudice the maintenance of the European patent.16 If necessary, the Opposition Division will invite the parties to file written observations.17 The patent proprietor may file a description, claims and drawings in amended form.18 Proposals for amendment to the patent – in practice, these proposals are filed as (auxiliary) claim requests – might not be considered if they are late-filed.19 Oral proceedings before the Opposition Division must be arranged if requested by a party.20 As a rule, oral proceedings in opposition proceedings are held by videoconference.21

At the conclusion of opposition proceedings, the Opposition Division may decide:

  • to reject the opposition and maintain the patent as granted;

  • maintain the patent in amended form; or

  • revoke the patent.22

Any party adversely affected by the Opposition Division’s decision may lodge an appeal with the Boards of Appeal. Such an appeal has suspensive effect.23