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Opposition proceedings: what are they and how do you win? | EP&C


www.epc.nlhubfs2023-01_EPC_Blog_Oppositieprocedure_Blog_2_Kolom_356x301I recently had another great day at work: my client's opposition proceedings were heard. Following intensive preparations I finally stood face to face with the opponent. After a long day full of arguments and counterarguments, we finally got a decision: my client had won the case and the patent was upheld. Time to explain what opposition proceedings are all about and how to increase your chances of winning them.

What exactly are opposition proceedings?

In opposition proceedings one party tries to get the other party's patent declared invalid. They are different from infringement proceedings where it is claimed that someone is counterfeiting a patented innovation and therefore infringing a patent.

In the case of opposition proceedings the aim is to have all or part of the patent declared invalid. For example, by claiming that it is not novel or inventive. So it is important to have a strong patent to start off with.

The challenging party is in a fairly comfortable position. It simply puts forward all the arguments it can come up with. For a patent owner the situation is often more stressful. This is because it has something to lose and has to prove that the patent was rightly granted and meets all the conditions.

The proceedings start in writing but almost always end with a hearing in which both parties are heard and can respond to each other's arguments.

EP&C conducts many of these proceedings and has a high success rate in them. Good preparations are half the battle in this case, both when you are being "attacked" and when you are trying to get a patent declared invalid yourself.

Grounds for opposition

So the opposing party or opponent is the one who wants to have the patent declared invalid and starts the opposition. This can, among other things, be done on the following grounds:

  • Novelty; the invention must be novel.
  • Inventive step: the invention must be non-obvious.
  • Replicability: the invention must be replicable based on the patent.
  • Addition: you may not claim something you did not originally file.


The aim of opposition proceedings is to establish whether the patent was wrongly granted based on one or more of these grounds. If this does indeed turn out to be the case, the patent owner may have to amend the claims. In the worst case scenario he will lose the patent. The opponent can then enter the market with the product. So you can imagine that the hearing is quite an important moment. This is where the final decision is made.

Written part of the opposition proceedings

The proceedings start with the opponent submitting the relevant documents. These contain information on what they want to challenge and on what grounds. The opponent will also submit arguments and documentary evidence to which the patent owner can respond in writing. The European Patent Office will then issue a preliminary opinion.

Hearing day

The day of the hearing is preceded by extensive preparations. The hearing is a formal affair. The European Patent Office will appoint a chairman and a primary and secondary examiner. They hear both parties who may also respond to each other. This can easily take a whole day or several days and is quite intensive.

There are many documents from which quotes will be made and sometimes there are experts to be heard. So a hearing day requires a lot of concentration and, above all, a lot of substantive knowledge of the patent with the details of all the claims. Foresight is better than hindsight, so for whatever the opposing party might bring up you have to have a good counter argument. This means it is crucial to surprise the opposing party and keep coming up with different angles.

Once everyone has been heard and has responded to each other, the decision will be made. This is when you will hear whether you will be able to keep your patent in its current form. After this you will only be able to dispute the outcome in an appeal.

Role of the patent attorney

As you have read, the stakes in opposition proceedings are high. You may end up losing your patent. And so we come to the answer to the question in the heading: how do you increase your chances of winning opposition proceedings? First of all, make sure you have a good patent to start with. You can arrange this under the expert guidance of patent attorneys.

It is also important during the proceedings that you are assisted by an experienced patent attorney. He or she will speak on your behalf and ensure that there is a proper response to every argument put forward by the opposing party.

EP&C has extensive experience in conducting opposition proceedings with a high success rate in both defending and challenging patents. Please contact us for more information. We will be happy to help you.