When harmless-error review of Erlinger error requires consideration by appellate judges of facts neither intrinsic to nor relevant to the finding of guilt for the simple § 922(g)(1) offense, is Erlinger error structural?

The Armed Career Criminal Act [“ACCA”] enhances the statutory penalty for a firearms offense under 18 U.S.C. § 922(g)(1) when the offender has three predicate convictions for offenses that were “committed on occasions different from one another.” 18 U.S.C. § 924(e)(1). In Erlinger v. United States, 602 U.S. 821 (2024), this Court held that the fact must be alleged in the indictment and proven to a jury beyond a reasonable doubt before the ACCA-enhanced penalty may be imposed—thereby establishing that the ACCA creates a separate, aggravated offense. In 2022, before this Court decided Erlinger, Petitioner Mark Sain was charged with and pleaded guilty to the simple § 922(g) offense. At sentencing, over Mr. Sain’s objection, the sentencing judge found the fact by a preponderance of the evidence and based on information outside the record of the plea proceeding, including Shepard documents. While his appeal was pending, this Court decided Erlinger, establishing that the ACCA sentence violated the Fifth and Sixth Amendments. The questions presented are: I. When harmless-error review of Erlinger error requires consideration by appellate judges of facts neither intrinsic to nor relevant to the finding of guilt for the simple § 922(g)(1) offense, is Erlinger error structural? II. If a preserved claim of Erlinger error is instead amenable to harmlesserror review, what is the proper test and corresponding scope of review when the defendant has pleaded guilty only to the lesser offense under § 922(g)(1)?