United States v. Casiano-Santana, 1 F.4th 100

Police observed Julio Casiano-Santana engage in a drug transaction and arrested him at the scene.
Officers recovered a loaded pistol and three bags of crack cocaine during the arrest.
Casiano was charged under 18 U.S.C. § 924(c)(1)(A)(i), 21 U.S.C. § 841(a)(1)/(b)(1)(C) (two counts), and 18 U.S.C. § 922(g)(1).
He moved to suppress the drugs, the firearm, and post-arrest statements; the district court denied the suppression motion.
Casiano pleaded guilty pursuant to a plea agreement to possession of a firearm in furtherance of drug trafficking and possession with intent to distribute; two other counts were dropped; he was sentenced to 103 months.
On appeal Casiano argued his plea was invalid because he did not know the plea waived his right to challenge the suppression denial; the issue was reviewed for plain error.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether Casiano’s guilty plea was invalid for failing to inform him that the plea waived his right to appeal the denial of his suppression motion	United States: Rule 11 and the plea colloquy satisfied the requirement; no plain error	Casiano: He misunderstood the plea’s consequences and did not know he waived the right to challenge the suppression ruling	Court affirmed—no clear or obvious Rule 11 error; defendant affirmed understanding during colloquy; even if error existed it wasn’t clearly established

United States v. Vonn, 535 U.S. 55 (plain-error review applies to unpreserved Rule 11 claims)
United States v. Díaz-Concepción, 860 F.3d 32 (1st Cir. 2017) (plain-error test articulation)
United States v. Smith, 511 F.3d 77 (1st Cir. 2007) (Rule 11 requires colloquy to ensure plea is knowing and voluntary)
Class v. United States, 138 S. Ct. 798 (2018) (unconditional guilty plea waives nonjurisdictional pre-plea constitutional claims)
United States v. Goodman, 971 F.3d 16 (1st Cir. 2020) (appeal waiver does not bar challenging the validity of the plea itself)