How to Invent and Protect Your Invention: A Guide to Patents for Scientists and Engineers

6.8 CHALLENGES AND CHANGES TO ISSUED PATENTS

Even after a patent is granted, patent holders cannot be certain that the claims will not be invalidated. According to Section 321 of the Patent Law, two proceedings—post-grant review and inter partes review—allow others to challenge the validity of a patent that has been granted by the PTO. These proceedings are similar, but not identical. The PTO has also begun using a new proceeding called supplemental examination through which patent holders can disclose information to strengthen their patent or correct inaccuracies. We provide a brief summary of similarities and differences.

6.8.1 Post-Grant Review

Post-grant review proceedings can be initiated by anyone within nine months of the grant of a patent, except for someone who has already initiated a civil lawsuit challenging the patent's validity. In a post-grant review proceeding, a challenger can seek to invalidate a patent for such reason as lack of novelty in light of the prior art, insufficient written description, or failure to enable those skilled in the art to reproduce the invention. An exception is that a patent cannot be challenged for failure to satisfy the best mode requirement.

While anyone can file for post-grant review, the Patent Trial and Appeal Board (PTAB) will only initiate a post-grant review if the challenger shows that it is more likely than not that at least one claim should have been unpatentable. The patentee can refute the challenge by filing a written argument ...