European Patent Office opposition proceedings

Patenthuis specializes in European patent opposition procedures. We will be happy to represent you at the EPO as an opponent against a granted European patent proprietors.

Anybody who believes a European patent was granted incorrectly may file an oppositionin order to obtain a revocation. 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, requiring a European patent attorney to handle opposition proceedings.

Did somebody oppose your patent and you need to defend yourself? Do you wish to file an opposition in order to get a revocation of a European patent? 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 revovation by EPO opposition proceedings


If you want to obtain the revocation of a European patent, 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 significant 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. This 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 the opponent has a stronger case. The opposite is, however, not the true: After a patent revocation in opposition, the owner can not use the national court systems to obtain a grant anyway.

Opponents and representation

Anyone may file an opposition against a granted European patent. An opponent does not need to demonstrate an interest.

However, parties not having a residence in the EPC member states need a European Patent Attorney to represent them. 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, we very strongly recommend also 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.

The opponent needs to present his arguments within this deadline as well. Often there is a lot of preparatory work before arguments are ready for filing. Therefore, please contact Patenthuis as 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 access 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, the opposition division reaches and announces their decision.

The result of an opposition is the revocation or the maintenance of the patent. A partial revocation is also possible and is actually quite common. This means that the outcome of the opposition is the revocation of at least one of the original claims but not of the entire patent.

Opposition Appeal

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

Grounds of opposition

The invention is not novel or inventive

This is a very common and useful ground. It means that the invention is the same as, or follows in an obvious manner from the prior art. The prior art includes everything that was available publicly before the filing date of the patent. If this is the case, this ground can often be invoked successfully.

During pre-grant examination, the examiner thoroughly investigates novelty and inventiveness. Of course there may be publications that the examiner did not find or did not use. Such publications are useful during the opposition procedure to argue that the claimed invention does not meet the basis requirements for patentability.

Often the opponent, being active in the exact technical field of the patent, has better knowledge than the examiner of which information was public, and has access to different documents than the examiner. Typically this concerns brochures, trade magazines, symposium proceedings, exhibitions etc. The examiners at EPO rarely use those types of disclosures spontaneously.

If the opponent does not have evidence of such public disclosures, Patenthuis can perform a specific prior art search.

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, this is a ground for revocation of the patent in opposition. During examination the examiners usually do not investigated this aspect in depth. The applicant often gets the benefit of the doubt. This ground of opposition, if presented well, offers good prospects of success to an opponent in some cases.

Extension of subject matter

If the application as filed did not disclose the features as claimed, this is a major ground for revocation. This happens quite regularly, especially if the claims as granted differ from 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 counter it 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

Exclusion from patentability means that by its nature the law excludes the invention from patentability. For instance because it is not industrially applicable, not technical or concerns a medical treatment. This ground is uncommon in opposition.