for certification for immediate appeal pursuant to 28 U. S. C. § 1292(b), Lauro Lines sought to appeal the District Court’s orders. The Court of Appeals for the Second Circuit dismissed petitioner’s appeal on the ground that the District Court’s orders denying petitioner’s motions to dismiss were interlocutory and not appealable under § 1291. The court held that the orders did not fall within the exception to the rule of nonappealability carved out for collateral final orders in Cohen v. Beneficial Industrial Loan Corp., 337 U. S. 541 (1949). 844 F. 2d 50 (1988). We granted certiorari to resolve a disagreement among the Courts of Appeals. 488 U. S. 887 (1988). Compare, e. g., 844 F. 2d 50 (1988) (case below); Rohrer, Hibler & Replogle, Inc. v. Perkins, 728 F. 2d 860, 862-863 (CA7) (<HOLDING>), cert. denied, 469 U. S. 890 (1984), with
holding that a motion to dismiss based on a forumselection clause should be treated as a rule 12b3 motion to dismiss for improper venue holding that the denial of a motion to remand is interlocutory and not immediately appealable holding prejudgment denial of motion to dismiss on basis of forumselection clause not to be immediately appealable under  1291 holding that a district court order denying a motion to stay or dismiss because of the pendency of similar litigation in state court is not immediately appealable under section 1291 or section 1292a1 holding that a forumselection clause may be enforced under rule 12b3 as a motion to dismiss on the basis of improper venue