Matthew John Hylton v. U.S. Attorney General, 992 F.3d 1154

Matthew Hylton was admitted from Jamaica (1993), naturalized on Sept. 16, 2008, and falsely affirmed no unarrested crimes at his ceremony.
Six days before naturalization he robbed a bank; he later pleaded guilty to armed bank robbery and unlawful transfer of a firearm, crimes qualifying as aggravated felonies.
In 2011 a jury convicted Hylton of obtaining citizenship by fraud and a district court revoked his U.S. citizenship (denaturalization).
In 2018 DHS charged Hylton removable under 8 U.S.C. § 1227(a)(2)(A)(iii) (aggravated-felony ground: "any alien who is convicted of an aggravated felony at any time after admission").
The IJ and a single-member Board decision sustained removal, relying on BIA precedent that denaturalized persons may be removed for convictions entered while they were citizens.
Hylton petitioned for review, arguing Costello v. INS barred applying the aggravated-felon removal ground to convictions entered while he was a citizen; the Eleventh Circuit granted relief.

Issue	Hylton's Argument	Government/Board's Argument	Held
Whether § 1227(a)(2)(A)(iii) applies to a denaturalized person whose predicate convictions occurred while he was a U.S. citizen	Costello bars application; statute should be read to exclude persons who were citizens at time of conviction	The statute’s plain words cover "any alien... convicted... after admission," so a denaturalized person is removable once citizenship is voided	Court held the provision does not apply to persons who were citizens at time of conviction; Costello controls
Whether denaturalization operates retroactively (ab initio) for removal, making the person an alien at time of conviction	Denaturalization should not be treated as retroactive for removal; Costello rejected retroactive effect in removal context	Denaturalization (8 U.S.C. § 1451(e)) relates back to the date of conviction, so one can be treated as an alien then	Court held denaturalization cannot be treated retroactively for removal; Costello forecloses that argument

Costello v. Immigration & Naturalization Serv., 376 U.S. 120 (1964) (held deportation ground with similar language did not apply to convictions incurred while petitioner was a citizen)
Nat'l Cable & Telecomms. Ass'n v. Brand X Internet Servs., 545 U.S. 967 (2005) (limits on agency deference when a court has already resolved statutory meaning)
United States v. Home Concrete & Supply, LLC, 566 U.S. 478 (2012) (pre-Chevron recognition of ambiguity does not necessarily establish Chevron ambiguity)
Epic Sys. Corp. v. Lewis, 138 S. Ct. 1612 (2018) (when canons supply an answer, Chevron step two need not apply)
Okpala v. Whitaker, 908 F.3d 965 (5th Cir. 2018) (discussed aggravated-felony removability in related context)