of the Administrative Procedure Act (“APA”). 5 U.S.C. § 706(2)(A); Gilmore v. Lujan, 947 F.2d 1409, 1411 (9th Cir.1991). Because estoppel is an equitable concept that is invoked by the court in its discretion, we review the district court’s rejection of appellants’ equitable estoppel argument under the abuse of discretion standard. See United States v. Ruby Co., 588 F.2d 697, 706 (9th Cir.1978) (Ely, J. dissenting) (“As my Brothers appropriately say, courts remain free to reject the application of estoppel to the Government, even though the required elements are present, when, in the exercise of their equitable discretion, they find that countervailing reasons of public policy so require.”); see also Scholle Corp. v. Blackhawk Molding Co., Inc., 133 F.3d 1469, 1471 (Fed.Cir.1998) (<HOLDING>). II. Appellants contend that under the Quiet
recognizing the abuse of discretion standard and the requirement of evidentiary support for a finding of estoppel holding that a district courtsfinding of equitable estoppel is reviewed under an abuse of discretion standard holding that the imposition of sanctions is reviewed for abuse of discretion recognizing that a district courts dismissal of an independent action under rule 60b is reviewed for abuse of discretion holding that the appropriate standard of review is abuse of discretion