EPO opposition proceedings at the European Patent Office

Patenthuis specializes in EPO opposition, in other words: European patent opposition procedures. We represent patent proprietors as well as opponents.

Anybody who believes a European patent was granted incorrectly may file an opposition. The opposition period is nine months following the grant. This is a strict deadline which can’t be extended.

In opposition, the patentability of the claims is re-evaluated. The arguments submitted by the opponent or opponents are then considered.

An opposition is a legal procedure having strict procedural requirements, often requiring a European patent attorney to handle opposition proceedings.

Did somebody oppose your patent and you need to defend yourself? You wish to file an opposition against a patent that you would like to be revoked? Patenthuis can conduct the procedure for you!

Irrespective of whether you want to oppose a European patent or whether you need to defend your European patent against an attack by somebody else, Patenthuis is at your service.

Advantages of centralized EPO opposition proceedings


If you want to have a European patent revoked, you have two choices: A centralized EPO opposition or country-by-country national patent revocation. This last option requires legal proceedings at the national courts of the various countries in Europe.

There are serious advantages to an EPO opposition. These are mainly: reduced cost and complexity. This is the case because there is only a single, centralized procedure.

Unfortunately, this procedure is only available for a period of nine months after grant.

Instead, if you want a European patent revoked after the nine-month opposition period, you will need to start legal procedures country by country. It will be clear that is more expensive and more complex.

There is a further advantage to EPO oppositions, at least for the opponent. If opposition is unsuccessful, the opponent still has the possibility to try to obtain patent revocation in the various national courts. This allows, for instance, to search harder, for stronger prior art, so that a stronger case can be presented. The opposite is not the case: if a patent is revoked in opposition, the owner can not use the national court systems to obtain a grant anyway.

Opponents and representation

Anyone an file an opposition against a granted European patent. No interest needs to be demonstrated.

However, parties not having a residence in the EPC member states need to be represented by a European Patent Attorney. There is no such requirement for parties having a residence in one of those member states. Due to the complexity of the opposition at EPO it is, however, it is very strongly recommended also for those parties to use a European Patent Attorney.

An opposition is an inter-partes procedure. This means in essence that the patent proprietor and the opponent(s) are parties to the proceedings, and an Opposition Division (OD) of the EPO acts as impartial arbiter. Whereas during examination the examiners may be forthcoming to the applicant and make suggestion to expediate grant, the people in the OD need to be strictly impartial.

Timing of opposition

Opposition needs to be filed within nine months from the date of grant of a European patent. This is a very strict, non-extendible deadline.

All the arguments need to be presented as well within this deadline. Often there is a lot of preparatory work to be done. Therefore, please contact Patenthuis soon as you are considering filing an opposition, preferably at least 2-3 months before the nine-month deadline.

EPO opposition proceedings take place at the EPO offices in The Hague (Netherlands) or Munich (Germany). We can easily drive to either location.

An opposition procedure usually involves two rounds of written arguments and usually ends with oral proceedings. Immediately at the end of the oral proceedings a decision is taken and announced.

The result of an opposition can be that the patent is revoked or upheld.

A partial revocation is also possible and is actually quite common. This means that one of the original claims was revoked, but that another, more limited claim, was upheld.

Opposition Appeal

The losing party may appeal the outcome of the opposition. An appeal needs to be filed within 2 months. Patenthuis will also be happy to represent you during the appeal proceedings.

Grounds of opposition

An opposition may in practice be based on one or more of the following grounds:

The invention is not novel or inventive

This ground is the most commonly used ground. It means that the invention is the same as, or follows in an obvious manner from, a product or method that was available publicly before the filing date of the patent. If this is the case, this ground can often be invoked successfully.

Novelty and inventiveness are thoroughly investigated during pre-grant examination. Of course there may be publications that the examiner did not find or did not use. Such publications can often be used during the opposition procedure to argue that the claimed invention did not meet the basis requirements for patentability.

Often the opponent, being active in the exact technical field of the patent, has better knowledge of what was made public and has access to different documents than the examiner. Typically this concerns brochures, trade magazines, symposium proceedings, exhibitions and standardization committees. The examiners at EPO rarely use those kinds of disclosures spontaneously because they are not so easy to find.

If the opponent does not have evidence of such public disclosures, a specific prior art search is strongly advised. Patenthuis can perform this for you.

The invention is not sufficiently disclosed

If a skilled person in the particular technical field can’t reproduce the invention without undue burden, based on his knowledge and the disclosure in the patent, the patent can be revoked in opposition. During pre-grant examination this aspect is usually not investigated in depth by the examiners, and the benefit of the doubt is often given to the applicant. This ground of opposition, if presented well, offers good prospects of success to an opponent in some cases.

Extension of subject matter

If the features as claimed were not disclosed in the application as filed a patent may not be granted. This happens quite regularly, especially if the claims as granted are amended compared to the application as filed. This argument is particularly usable in opposition.

This argument is especially attractive because it is usually impossible for the patent proprietor to rescue part of his patent by making amendments.

Often, if an error, even a small error, occurred in making amendments during pre-grant examination, such an error is fatal to the patent.

Exclusion from patentability

This means that by its nature the invention is not patentable. For instance because it is not industrially applicable, not technical or concerns a medical treatment. This ground is not used very often in opposition.