What is the test for granting a preliminary injunction?

We review for abuse of discretion a district court's grant of a preliminary injunction. Blum v. Schlegel, 18 F.3d 1005, 1010 (2d Cir.1994). An abuse of discretion may be demonstrated by showing that the injunction is based on an error of law. County of Seneca v. Cheney, 12 F.3d 8, 11 (2d Cir.1993). For reasons explained below, we hold that the district court committed such an error of law in granting the injunction, thereby abusing its discretion. We therefore vacate the preliminary injunction and remand.