Proceedings before the TTAB are in many ways “similar to a civil action in a federal district court.” They are governed by the Federal Rules of Civil Procedure and Evidence. The TTAB also allows discovery and depositions. The primary way in which TTAB proceedings differ from ordinary civil litigation is that “proceedings before the Board are conducted in writing, and the Board’s actions in a particular case are based upon the written record therein.” In other words, there is no live testimony. Even so, the TTAB allows parties to submit transcribed testimony, taken under oath and subject to cross-examination, and to request oral argument. B&B (P) and Hargis (D) both manufacture metal fasteners. P for the aerospace industry, and D for use in the construction trade. In 1993, P registered SEALTIGHT for “threaded or unthreaded metal fasteners and other related hardware; namely, self-sealing nuts, bolts, screws, rivets and washers, all having a captive O-ring, for use in the aerospace industry.” In 1996, D sought to register SEALTITE for “self-piercing and self-drilling metal screws for use in the manufacture of metal and post-frame buildings.” P opposed D's registration because, although the two companies sell different products, it believes that SEALTITE is confusingly similar to SEALTIGHT. In 2002, when the PTO published SEALTITE in the Official Gazette, this prompted opposition proceedings before the TTAB, complete with discovery, including depositions. P argued that SEALTITE could not be registered because it is confusingly similar to SEALTIGHT. TTAB sided with P. Despite a right to do so, D did not seek judicial review in either the Federal Circuit or District Court. All the while, P had sued D for infringement. Before the District Court ruled on likelihood of confusion, TTAB announced its decision. P argued to the District Court that D could not contest likelihood of confusion because of the preclusive effect of the TTAB decision. The District Court disagreed in that the TTAB is not an Article III court. The jury returned a verdict for D, finding no likelihood of confusion. P appealed to the Eighth Circuit and lost. The Supreme Court granted certiorari.