district court must order appellants to file their arbitration in Tennessee. The decision of the district court is reversed in part and the ease is remanded for action consistent with this opinion. Reversed in part and Remanded. 1 . Although we acknowledge the precedential validity of the principle last presented in Young v. Leventhal, 389 F.3d 1 (1st Cir.2004) (the applicability of a forum selection clause in an arbitration agreement is a matter of procedure to be decided by the arbitrator), and its probable applicability to the present circumstances, this issue was not argued by the parties before either the bankruptcy or district courts, nor briefed or argued before us, and is thus deemed waived. See, e.g., Garcia-Ayala v. Lederle Patentarals, Inc., 212 F.3d 638, 645 (1st Cir.2000) (<HOLDING>) (internal citations omitted); Sprague v. Dir.,
holding that failure to raise issue in brief constitutes waiver of appeal of the issue holding that the failure to oppose a basis for summary judgment constitutes waiver of that argument on appeal holding that the failure to object to an instruction constitutes a waiver of error holding that the failure to identify or argue an issue in an opening brief constitutes waiver of that argument on appeal holding that failure to brief an argument constitutes waiver