At any time after the grant of patent but before the expiry of nine months from the date of publication of grant of patent in European Patent Bulletin, any person except Patent Proprietor may oppose the grant of patent after the payment of prescribed fee on the following grounds:
- that the subject-matter of the patent is not patentable within the terms of Articles 52-57 of EPC;
- that the invention is not disclosed clearly and completely enough for a person skilled in the art to carry it out;
- that the patent’s subject-matter extends beyond the content of the application as filed.
There are three possible consequences at the end of the proceedings:
- the opposition is rejected and the patent is maintained as granted;
- the patent is maintained in an amended form, in which case a new patent specification is published;
- the patent is revoked.
The opposition applies to all states designated in the European patent. The decision/order of the opposition divisions in respect of the opposition can be appealed within two months from the date of notification of the decision.