The collateral order exception to the final judgment rule authorizes interlocutory appeals from a small category of orders: those that conclusively determine disputed questions, resolve important issues completely separate from the merits of the action, and are effectively unreviewable on appeal from a final judgment. The question presented in this case was whether a district court decision denying a motion to dismiss based on the so-called Parker state-action defense to antitrust liability is among this small category. Public Citizen submitted an amicus brief to explain why the collateral order doctrine does not authorize interlocutory appellate jurisdiction over district court decisions denying motions to dismiss based on a defendant’s failure to satisfy the “state-action” defense to antitrust liability that this Court announced in Parker v. Brown, 317 U.S. 341 (1943). The brief explained that a contrary holding would risk expanding the collateral order doctrine beyond the small class of interlocutory orders currently authorized for immediate appellate review. Shortly before the Court heard argument, the parties settled the case and stipulated to dismissal.