Oil States Energy Services, LLC (Oil States) (plaintiff) was an oilfield service company that obtained a patent related to hydraulic fracturing. Oil States sued Greene’s Energy Group, LLC (Greene’s) (defendant) in federal court for infringing that patent. Greene’s responded by challenging the patent’s validity. Greene’s also petitioned the Patent Trial and Appeal Board (the board) to institute inter partes review. Greene’s argued that the patent’s claims were unpatentable because they were anticipated by prior art not mentioned by Oil State in its original patent application. The federal court issued an order foreclosing the arguments Greene’s made about the prior art. The board, however, later issued a final decision concluding that the claims were unpatentable. The board acknowledged the federal court’s contrary decision, but concluded that the claims were anticipated by the prior art. Oil States appealed to the United States Court of Appeals for the Federal Circuit. Oil States challenged the constitutionality of inter partes review. Oil States argued that actions to revoke a patent must be tried in an Article III court before a jury. While Oil States’s case was pending, the Federal Circuit rejected the same constitutional argument in another case and affirmed the board’s decision in Oil States’s case. The Supreme Court granted cert.