European Patent Office (EPO) Opposition Procedure

How and when can a European patent be opposed?

The period within which an opposition may be filed is fixed at nine months from the date of grant of the patent. Outside of the opposition period, the validity of a European patent may only be challenged on a country-by-country basis, for example by filing separate revocation actions in each of the countries covered by the patent.

Filing an opposition requires completion of the following acts:

1. Payment of an opposition filing fee;
2. Filing a notice of opposition; and
3. Filing facts and arguments in support of the notice of opposition.

The opposition must set out the basic case against the patent and provide references to any prior art or other evidence relied on. The notice of opposition may request complete or partial revocation of the patent. It is important to set out reasons why the patent should be revoked or amended in as much detail as possible at the outset; any supplementary evidence relied upon should be notified to the EPO and the other parties to proceedings as soon as practicable after filing the notice of opposition.

On what grounds can a European patent be opposed?

A European patent may be opposed on one or more of the following grounds only:

1. The claimed invention is not patentable, i.e. the subject matter of the patent is excluded from patentability, or because it lacks novelty or an inventive step;
2. The specification of the patent does not disclose the invention sufficiently clearly and completely for it to be carried out by a person skilled in the art (“sufficiency”); and
3. The subject matter of the European patent extends beyond the content of the European application as originally filed (“added subject matter”).

What happens after an opposition has been filed?

Following receipt of an opposition the patent proprietor is given an opportunity to provide counter-arguments and/or amendments in response to the grounds of opposition. It is possible for there to be one or two additional rounds of correspondence between the parties during this phase of the opposition proceedings.

Although opposition proceedings are primarily a written procedure, it is usual for the proceedings to culminate in an oral hearing at the EPO where all parties to the proceedings are invited to present their case. The hearing takes place before an Opposition Division which consists of a panel of three EPO examiners.

At the end of the hearing (which usually lasts up to one day), the Opposition Division typically announces its decision to maintain (as granted or in amended form) or to revoke the opposed patent. The reasons for the decision are communicated to the parties in writing at a later date and this written decision initiates the opportunity for filing an appeal.

Can a decision of the EPO Opposition Division be appealed?

Any party to the opposition proceedings that is adversely affected by the decision of the Opposition Division may file an appeal. A notice of appeal and appeal fee must be paid within two months of notification of the decision from the Opposition Division. Within four months of notification of the decision, a detailed statement setting out the grounds of the appeal must also be filed.

Is it possible to oppose a European patent application?

It is not possible to oppose a pending European patent application. However, in proceedings before the EPO, following publication of the European application, any third party may file observations (anonymously if desired) concerning the patentability of the invention to which the application relates. The third party is not made a party to proceedings and is therefore not notified of any decisions in the procedure. Third party observations may also be filed during opposition and appeal proceedings.

My European patent has been opposed. What should I do?

For advice in relation to a specific situation please contact your usual D Young & Co advisor.