In the US, there are at least two USPTO proceedings that can be filed by third parties against invalid or unduly broad patents (e.g., in light of prior art not considered during prosecution):

  1. Ex Parte Re-Examination
  2. Post-grant review (up to 9 mo after grant) / Inter-partes review (starting 9 mo after grant)

However, the EPO appears to have limited options for post-grant challenges (see wikipedia article):

  1. "Limitation" proceedings (analogous to US re-exam), which can only be initiated by the patentee.
  2. "Opposition" proceedings, which are only available up to 9 months after grant (analogous to US PGR).

I am not aware of the upcoming UPC changes affecting these options. So is this the extent of options for patent challenges at the EPO -- i.e. no options after 9 months?

I have some very strong (102/novelty) prior art that was not considered during examination, and I will miss the 9 month window. However, bringing this up in litigation requires legal standing (which seems to essentially require infringement for savvy patentees who avoid triggering standing), which could push the patentee to counterclaim infringement, which could result in an even longer/pricier process, esp. if the court is DE (mandatory bifurcation) or UPC (discretionary bifurcation). The only other out is if the patentee decides not to litigate due to the EPO "loser pays" fee shifting in light of the strength of the prior art.

  • 1
    Well if you mention limitation proceedings, technically there's also revocation proceedings, which is basically the same just limiting the patent to no patent. But I've never understood why anybody would initiate those on their own patent anyways.
    – user18033
    May 20, 2018 at 11:48

1 Answer 1


So is this the extent of options for patent challenges at the EPO -- i.e. no options after 9 months?


Once the 9 month opposition period finishes, the only way to revoke another person's patent is to commence a revocation action in each country. For example, if a European patent was validated in the UK, France, and Germany, this would require three separate revocation actions: one in each country. It is consequently possible for a patent to be found invalid in some and valid in others. Similarly, standing and costs will be determined separately in each action. This makes revocation a high stakes course.

This will fundamentally change for the UPC, which will centrally determine validity for all UPC states in a single action. This makes revocation easier in some ways.

As a practical matter, it would be much more common to hold on to invalidating prior art until you're threatened with infringement, for exactly the reasons you mention. When the first shot is fired, it can trigger a litigation war, and that benefits no one. Much better to keep your powder dry, so to speak.

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