Post-grant review

U.S. patent law
Post-grant review is a

"proceeding [that] allows anyone who is not the patent owner to request a review of an issued patent that challenges at least one of the claims' patentability in more circumstances than inter partes review &mdash; such as the invention not being useful &mdash; and not solely based on prior art. This proceeding is available for patents issued from patent applications with a filing date of March 16, 2013, or later and requests must be filed within 9 months of the patent's issuance."