United States v. Faulkner, 950 F.3d 670

Defendant Jared Faulkner was convicted in federal court of being a felon in possession of a firearm (18 U.S.C. § 922(g)).
His Presentence Investigation Report counted a prior Oklahoma conviction for "endeavoring to manufacture methamphetamine" (Okla. Stat. tit. 63, § 2-408) as a "controlled substance offense," raising his Guidelines base offense level to 20 (total offense level 22) and producing an 84–105 month advisory range; the district court adopted the PSR and sentenced him to 96 months.
Faulkner did not object in district court and appealed under plain-error review (Fed. R. Crim. P. 52(b)), arguing his prior Oklahoma conviction does not qualify as a "controlled substance offense" under U.S.S.G. § 4B1.2(b).
The Circuit applied the categorical/modified categorical approach, assumed (without deciding) the Oklahoma statute was divisible, and compared Oklahoma "endeavoring" to the generic definition of "attempt."
The Tenth Circuit concluded Oklahoma "endeavoring" sweeps more broadly than generic "attempt" (so treating the conviction as a controlled-substance predicate was error), but the court held the error was not "plain" under Rule 52(b) and therefore affirmed the sentence.

Issue	Faulkner's Argument	Government's Argument	Held
Whether Faulkner's prior Oklahoma conviction for "endeavoring to manufacture" qualifies as a "controlled substance offense" under U.S.S.G. § 4B1.2(b)	"Endeavoring" encompasses "any effort" and can criminalize mere preparation, so it is broader than generic "attempt" and does not match § 4B1.2(b)	"Endeavoring" is equivalent to or includes attempt or aligns with listed federal possession-with-intent offenses, so it qualifies	The conviction is not a categorical match with the Guidelines' definition (district court erred in treating it as a predicate), but the error was not plain on appeal; sentence affirmed.
Whether the district court's error was "plain" under plain-error review (Rule 52(b))	Prior Tenth Circuit and Supreme Court precedent make it obvious that a non-matching prior conviction cannot be used as a § 4B1.2(b) predicate	Government conceded that if error was plain, prongs 3 and 4 of plain-error review are satisfied; argued error was not obvious given lack of controlling precedent	Court: Error was not "clear or obvious" under well-settled law; no controlling precedent made the precise issue plain, so plain-error relief denied.

United States v. McKibbon, 878 F.3d 967 (10th Cir. 2017) (applied categorical approach and held certain "offer" statutes do not qualify as controlled-substance predicates; discussed plain-error analysis)
United States v. Madkins, 866 F.3d 1136 (10th Cir. 2017) (held a Kansas "offer"/possession-with-intent formulation can be broader than an attempt-based predicate)
Tidmore v. State, 95 P.3d 176 (Okla. Crim. App. 2004) (OCCA: Oklahoma "endeavoring" is distinct from attempt and does not require an overt/perpetrating act)
Mathis v. United States, 136 S. Ct. 2243 (2016) (controls divisibility inquiry: elements vs. means under the categorical/modified categorical approach)
United States v. Mendez, 924 F.3d 1122 (10th Cir. 2019) (framework for defining generic offenses and applying the categorical approach)