European patent oppositions – a brief guide to opposing a European patent at the European Patent Office (EPO)

The Opposition procedure can be used to challenge the validity of another parties granted European patent before the European Patent Office.  The procedure is centralised which means that a successful challenge will be effective in all of the European contracting states covered by the granted patent.  The Opposition procedure is a popular tool in European patent practice.  It can filed anonymously so the true identity of the Opponent does not have to be revealed.  We have successfully attacked and defended valuable European patents for our clients. A brief outline of the opposition procedure follows below:

i. Grounds for challenging validity
A European patent can be challenged on the grounds that at least: (i) the claimed invention is not patentable (ie. it is not novel and/or inventive); (ii) the patent insufficiently describes how to perform the invention; and/or (iii) the granted patent contains new matter which extends beyond the scope of the application as filed.

ii. Preparing a Notice of Opposition
A notice of Opposition must include a written reasoned statement indicating the facts, the evidence, and arguments relied upon. An Opposition fee must also be paid. The notice of Opposition has to be filed and the fee paid within nine months of the publication of the mention of grant of the European patent. 

iii. Evidence and arguments
The likelihood of success of the Opposition will depend upon the strengths and weaknesses of the arguments that are filed in the notice of Opposition. To attack the patentability of the invention, it is necessary to submit prior art documents in order to argue that the alleged invention lacks novelty and/or inventive step. We are able to assist client’s in this regard in order to develop the strongest attacks.

iv. Examination of the Opposition
The notice of Opposition will be forwarded to the patentee for comment who may submit counter-arguments and optionally, amended claims, may be filed. The opponent will receive a copy of the patentee’s response upon which they may comment. In fact, any number of further observations from the patentee or the opponent can be filed until such time as the Opposition Division decides that they are able to reach a decision or issue a summons to oral proceedings.  At the oral proceedings, after hearing the parties arguments, a decision will be reached which will be to revoke the patent, to maintain the patent as granted, or to maintain the patent in amended form. After a few months, a written decision outlining the Opposition Division’s reasoning for their decision will be issued. This decision can be appealed to the EPO’s Board of Appeal by any of the parties adversely affected by the decision.

If you require any further information on opposing a European patent or have received a Notice of opposition filed by a third party then please contact us

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