Ex Parte Reexamination

May 15, 2017

Ex Parte Reexamination may be requested by either a patent owner or a third party in order to challenge the novelty or non-obviousness of one or more claims in a patent. The scope of prior art submitted in support of the challenge is limited to printed publications and patents, while other types of prior art (such as product prior art) are inadmissible.

A request for Ex Parte Reexamination can be filed at any time after a patent is granted and up to six years after it expires (a case-by-case determination may result in longer or shorter applicable time periods). A third party’s involvement ceases after the party files the request. Upon review, the central reexamination unit of the US Patent and Trademark Office (USPTO) will decide whether submitted prior art raises a substantial new question of patentability. Although Ex Parte Reexaminations may take several years to conclude, there is no statutory time limit for the proceedings.

Ex Parte Reexamination provides several benefits for a third-party challenger compared to other proceedings used to invalidate a patent:

  • Ex Parte Reexamination is a cost-effective alternative to litigation.
  • The request can be submitted anonymously, e.g., the challenger may engage a third party for filing the request, thereby avoiding attention from the patent owner.
  • The patentability threshold is lower than in court proceedings, increasing the likelihood of invalidating the challenged patent.
  • Claims of the challenged patent are often narrowed, effectively removing an infringing article from the scope of the reexamined patent claims (amendment also has negative implications).
  • Ex Parte Reexamination proceedings do not create legal estoppel.

Ex Parte Reexamination is not only available to challenge a patent; patent owners also may use the proceeding to test an issued patent, e.g., with prior art that was not considered during the original examination. A patent owner looking to assert its patent, and therefore anticipating an invalidity challenge, may choose to initiate an Ex Parte Reexamination before any litigation to resolve any anticipation or obviousness concerns about the patent. Having survived an Ex Parte Reexamination, the patent then becomes more difficult to invalidate in a court proceeding on similar challenges.