12 ABBOTT v. PEREZ Opinion of the Court districting plans now in effect to conduct this year’s elections. A The Judiciary Act of 1789, 1 Stat. 73, “established the general principle that only final decisions of the federal district courts would be reviewable on appeal.” Carson v. American Brands, Inc., 450 U. S. 79, 83 (1981) (emphasis deleted). But because “rigid application of this principle was found to create undue hardship in some cases,” Congress created exceptions. Ibid. Two are relevant here. We have jurisdiction under 28 U. S. C. §1253 to hear an appeal from an order of a three-judge district court “granting or denying . . . an interlocutory or permanent injunction.” Similarly, §1292(a)(1) gives the courts of appeals jurisdiction over “[i]nterlocutory orders of the district courts” “granting, continuing, modifying, refusing or dissolving injunctions,” “except where a direct review may be had in the Supreme Court.” The orders in these cases fall within §1253. To be sure, the District Court did not call its orders “injunctions”—in fact, it disclaimed the term, App. 134a–136a—but the label attached to an order is not dispositive. We have previously made clear that where an order has the “practical effect” of granting or denying an injunction, it should be treated as such for purposes of appellate jurisdiction. Carson, supra, at 83; see also Gulfstream Aerospace Corp. v. Mayacamas Corp., 485 U. S. 271, 287–288 (1988). We applied this test in Carson, holding that an order that declined to enter a consent decree prohibiting certain conduct could be appealed under §1292(a)(1) because it was the practical equivalent of an order denying an injunction and threatened serious and perhaps irreparable harm if not immediately reviewed. 450 U. S., at 83–84, 86–90. This “practical effect” rule serves a valuable purpose. If