Full Opinion

United States Court of Appeals For the Eighth Circuit ___________________________ No. 25-2288 ___________________________ United States of America Plaintiff - Appellee v. Justin Dequize Preston Defendant - Appellant ____________ Appeal from United States District Court for the Eastern District of Arkansas - Central ____________ Submitted: September 21, 2026 Filed: October 28, 2026 [Unpublished] ____________ Before GRUENDER, KELLY, and KOBES, Circuit Judges. ____________ PER CURIAM. Justin Preston pleaded guilty to one count of possession of a stolen firearm, in violation of 18 U.S.C. §§ 922(j) and 924(a)(2). In the plea agreement, Preston and the United States jointly recommended a 120-month sentence. The plea agreement also specified that in exchange for the United States’ dismissal of the remaining counts in the indictment, Preston would waive the right to appeal all non- jurisdictional issues except for claims of prosecutorial misconduct. The district court 1 accepted the plea agreement and imposed the sentence jointly recommended by the parties. Preston appeals, arguing (i) that his trial counsel was ineffective and (ii) that the United States engaged in prosecutorial misconduct by introducing testimony at a suppression hearing that prosecutors knew, or should have known, was false. The United States moved to dismiss the appeal, arguing that it runs afoul of the plea agreement’s appeal waiver. Preston cannot prevail on either of the arguments he advances. First, we have explained that “ordinarily, we do not address claims of ineffective assistance of counsel on direct appeal because such claims usually involve facts outside of the existing record and are therefore best addressed in postconviction proceedings under 28 U.S.C. § 2255.” United States v. Adkins, 636 F.3d 432, 434 (8th Cir. 2011). In keeping with that norm, Preston’s plea agreement specifically leaves open his ability to pursue an ineffective-assistance claim in post-conviction proceedings under § 2255. Accordingly, we decline to consider Preston’s ineffective-assistance arguments in this posture. Second, Preston’s prosecutorial-misconduct argument is too cursory to survive. Federal Rule of Appellate Procedure 28(a)(8)(A) requires that an appellant’s argument contain “contentions and the reasons for them, with citations to the authorities and parts of the record on which the appellant relies.” But Preston cites neither the record nor legal authorities in his one-paragraph prosecutorial- misconduct argument. And “we regularly decline to consider cursory or summary arguments unsupported by facts or legal authorities.” United States v. Sigillito, 759 F.3d 913, 933 (8th Cir. 2014) (citation modified). Accordingly, because Preston “has failed to go beyond a cursory assertion of this argument,” he is entitled to no 1 The Honorable Kristine G. Baker, Chief Judge, United States District Court for the Eastern District of Arkansas. -2- consideration of the merits of the prosecutorial-misconduct issue. United States v. Warren, 788 F.3d 805, 813-14 (8th Cir. 2015). For the foregoing reasons, we affirm.2 ______________________________ 2 We correspondingly dismiss as moot the United States’ motion to dismiss the appeal based on the appeal waiver. Cf. United States v. Harrison, 37 F.4th 495, 502 (8th Cir. 2022) (resolving appeal on the merits, then denying as moot the United States’ motion to dismiss based on an appeal waiver). -3-