EPO oppositions and appeals

Our patent attorneys are proven specialists in European Patent Office oppositions and appeals

On the surface, an opposition at the European Patent Office (EPO) is a central invalidity procedure that can lead to the cancellation or restriction of a European patent in every country in which it is in force. If successful, an opposition can remove the risk of patent infringement and secure the freedom to commercialise existing or future products.

However, on closer inspection, an opposition is also a tool that can be used to great commercial and strategic benefit.

It can:

  • Provide clarity about the scope of the patent and/or force explicit clarification of the scope.
  • Provide a basis to stay any patent infringement proceedings brought before a national court.
  • Pave the way to reaching a settlement with your competitor, such as obtaining an acceptable licence under the patent.

Given the commercial stakes involved in an EPO patent opposition, it is vital to have the right opposition strategy in place from day one.

This is where we come in.

We know how to run and win opposition cases.

Our overall success rate of 72% is impressive.

When we represent the opponent, the patent is 28% more likely to be revoked than when we represent the patentee; and when we represent the patentee, the patent is three times as likely to be maintained as granted than when we represent the opponent.

These figures show why Potter Clarkson is consistently chosen ahead of other European firms to handle the most commercially important and technically complex EPO patent opposition and appeal cases. We’ve acted for some of the world’s largest and best-known companies; we’ve also helped smaller ones defeat their much larger and better-resourced competitors in situations where the viability of the entire business was at stake.

Currently, we’re handling around 370 opposition cases. Over the last ten years we have handled 759 oppositions and 372 appeals.

These cases have involved us attacking or defending some of the most valuable European patents across a wide range of technological areas and industry sectors.

In all cases, we focus on delivering the best commercial value to our clients. Sometimes this involves working with our litigators to devise a wider enforcement/defence strategy, which may involve parallel litigation in multiple jurisdictions.

Our ability to offer a fully integrated, multidisciplinary team made up of hugely experienced patent attorneys and IP solicitors adds an extra dimension to the way we can defend and enforce your patent rights in Europe and beyond.

Being able to unify your litigation and opposition strategies ensures you always have a full set of tools at your disposal, maximising your prospects of achieving the outcome you want.

Better still, because we are working with colleagues rather than external lawyers, we can act for you immediately and work together in a more efficient, cost-effective way.


Potter Clarkson’s specialist oppositions team is made up of patent attorneys with long and exceptional records of attacking and defending patents at the EPO, as well as handling the resulting appeals. Many of them have each handled more than 100 oppositions and appeals, developing their advocacy skills before the EPO Opposition Divisions and Boards of Appeal.

A successful opposition (or the successful defence of an opposed patent) requires very different skills and expertise from the prosecution of a patent application to grant, particularly when one enters the appeal phase.

Their experience means our dedicated opposition team possesses both these skills and this expertise.

Just as importantly, our attorneys have repeatedly shown their ability to devise a variety of innovative approaches to optimise our clients’ prospects of success in an opposition, whether they are the opponent or the patentee.

This creativity is often the crucial success factor in our most difficult cases. The willingness of our attorneys to shape rather than follow existing case law is shown by the fact that 17% of the appeal cases we have handled are recognised in the Case Law of the Boards of Appeal of the EPO as cases that established some notable legal principle.