Appealing the Judgment in a Criminal Case following a remand for resentencing, Daniel Munoz raises arguments challenging the constitutionality of 21 U.S.C. §§ 841 and 851 that he concedes are foreclosed by the law of the case doctrine and by Almendarez-Torres v. United States, 523 U.S. 224, 235, 118 S.Ct. 1219, 140 L.Ed.2d 350 (1998). See United States v. Mata, 491 F.3d 237, 245 (5th Cir. 2007) (holding that constitutional challenges to §§ 841 and 851 are foreclosed by Almen- darez-Tmres); United States v. Matthews, 312 F.3d 652, 657 (5th Cir. 2002) (holding that under the law of the case doctrine, an issue of fact or law decided on appeal may not be reexamined by the appellate court on a subsequent appeal). The Government’s motion for summary af-firmance is GRANTED, and the judgment of the district court is AFFIRMED.