FILED
                                                                    United States Court of Appeals
                                      PUBLISH                               Tenth Circuit

                      UNITED STATES COURT OF APPEALS                    September 11, 2020

                                                                       Christopher M. Wolpert
                            FOR THE TENTH CIRCUIT                          Clerk of Court
                        _________________________________

 UNITED STATES OF AMERICA,

       Plaintiff - Appellee,

 v.                                                         No. 19-2022
                                                  (D.C. No. 1:17-CR-01714-JCH-1)
 PATRICK CALVIN BEGAY,                                        (D. N.M.)

       Defendant - Appellant.
                      _________________________________

                     Appeal from the United States District Court
                           for the District of New Mexico
                         (D.C. No. 1:17-CR-01714-JCH-1)
                       _________________________________

Submitted on the briefs:*

Brian A. Pori, Assistant Federal Public Defender, Albuquerque, New Mexico, for
Defendant-Appellant.

John C. Anderson, United States Attorney, Albuquerque, New Mexico, for Plaintiff-
Appellee.
                       _________________________________

Before LUCERO, MURPHY, and EID, Circuit Judges.
                 _________________________________

LUCERO, Circuit Judge.
                    _________________________________


      *
        After examining the briefs and appellate record, this panel has determined
unanimously to honor the parties’ request for a decision on the briefs without oral
argument. See Fed. R. App. P. 34(f); 10th Cir. R. 34.1(G). The case is therefore
submitted without oral argument.
      This case involves disparities in the sentences received by Native Americans

in federal court for aggravated assault as compared to state-court sentences for

similar conduct. Although we are sympathetic to Begay’s argument that but for an

“an accident of history and geography,” he would have received a lighter sentence,

we conclude that our precedents foreclose the consideration of federal/state

sentencing disparities under 18 U.S.C. § 3553(a)(6). Accordingly, exercising

jurisdiction under 28 U.S.C. § 1291, we affirm the judgment of the district court.

                                           I

      Begay assaulted a man in the Navajo Nation with a baseball bat and a knife.

The crime thus occurred in Indian country, within the boundaries of the reservation.

Both Begay and the victim are enrolled members of the Navajo Nation. Begay was

indicted in federal court on two counts of assault with a dangerous weapon and one

count of assault resulting in serious bodily injury. He pled guilty to these charges.

      The Probation Office issued a Presentence Report (“PSR”) calculating Begay’s

guidelines imprisonment range to be 46 to 57 months. By analogy to Kimbrough v.

United States, 

(2007), Begay requested that the court vary from this

range because significantly higher penalties are imposed on Native Americans

convicted of assault in New Mexico federal court than in New Mexico state court.

Defense counsel requested to submit testimony regarding this asserted sentencing

disparity. The government objected, arguing that under our precedents, if the district

court “even considers this argument or this train of argument in any way whatsoever,

any sentence rendered by the [c]ourt becomes invalid.” The sentencing judge agreed,

                                           2
stating that she could not consider Begay’s sentencing-disparity argument under our

unpublished decision in United States v. Beaver, 749 F. App’x 742 (10th Cir. 2018)

(unpublished), and moreover, she would not consider this argument because the

evidence Begay offered to present lacked sufficient detail to make any comparison of

his sentence to state-court sentences meaningful.

      Begay was sentenced to 46 months’ imprisonment. He appeals, challenging

the reasonableness of his sentence.

                                           II

      We review a district court’s sentencing decision for reasonableness.

“[R]easonableness review has two aspects: procedural and substantive.” United

States v. Cookson, 

, 1091 (10th Cir. 2019). “Review for procedural

reasonableness focuses on whether the district court committed any error in

calculating or explaining the sentence.” United States v. Friedman, 

,

1307 (10th Cir. 2009). Substantive reasonableness addresses “whether the length of

the sentence is reasonable given all the circumstances of the case in light of the

factors set forth in 18 U.S.C. § 3553(a).” United States v. Verdin-Garcia, 

, 895 (10th Cir. 2008) (quotation omitted). Section 3553(a) includes an

“overarching provision instructing district courts to ‘impose a sentence sufficient, but

not greater than necessary,’ to accomplish the goals of sentencing” set forth in

§ 3553(a)(2). 

(quoting § 3553(a)). The statute

enumerates several factors that the sentencing court “shall consider.” § 3553(a). Of

particular relevance to this appeal is § 3553(a)(6), under which a sentencing court

                                           3
considers “the need to avoid unwarranted sentence disparities among defendants with

similar records who have been found guilty of similar conduct.”

      “We review sentences for reasonableness under a deferential abuse of

discretion standard.” United States v. Haley, 

, 1311 (10th Cir. 2008)

(citation omitted). Under this standard, we will reverse a sentence if it is “arbitrary,

capricious, whimsical, or manifestly unreasonable.” United States v. Muñoz-Nava,

, 1146 (10th Cir. 2008) (quotation omitted). “A district court by

definition abuses its discretion when it makes an error of law.” Koon v. United

States, 

, 100 (1996).

                                            A

      Citing Kimbrough, Begay argues that sentencing courts are not prohibited

from considering whether sentences imposed on Native Americans for aggravated

assault are unfairly harsh because Native Americans are disproportionately subject to

federal jurisdiction. In Kimbrough, the Supreme Court upheld a district court’s

decision to impose a below-guidelines sentence on a defendant who pled guilty to

charges relating to the possession and distribution of crack 

-

93. The Court began by explaining that the 100-to-1 disparity in crack and powder

offenses—treating each gram of crack cocaine as equivalent to 100 grams of powder

cocaine—originated in the Anti-Drug Abuse Act of 1986 (“ADAA”) and was based

on several false assumptions about the relative harmfulness of the two drugs.

It further explained that the Sentencing Commission, in adopting the ADAA’s

“weight-driven scheme” to set base offense levels for drug-trafficking, acted outside

                                            4
its “characteristic institutional role” to formulate sentencing standards based on

“empirical data and national experience.”

(quotation omitted). The

Court also noted that the Commission itself had determined that the disparity was

“generally unwarranted” for several reasons, including that it disproportionately

affected African Americans and thereby “foster[ed] disrespect for and lack of

confidence in the criminal justice system.”

(quotations and citations

omitted). Consistent with these conclusions, the Commission attempted several

times—in 1995, 1997, 2002, and 2007—to reduce the crack/powder disparity, with

limited success. See

      Against this background, the district court sentenced Kimbrough below the

recommended guidelines range. The court reasoned that the crack/powder cocaine

disparity in the Guidelines “drove the offense level to a point higher than is necessary

to do justice in this case.”

(alteration omitted). The Fourth Circuit

reversed, holding that “a sentence outside the guidelines range is per se unreasonable

when it is based on a disagreement with the sentencing disparity for crack and

powder cocaine offenses.”

      Reversing the Fourth Circuit, the Supreme Court began from the premise

stated in United States v. Booker, 

(2005), that the Guidelines are no

longer mandatory, and the district court is tasked with “impos[ing] a sentence

sufficient, but not greater than necessary” to accomplish the goals of sentencing

provided in § 

(quotation omitted). The Court concluded

that consistent with this directive, “the District Court properly homed in on the

                                           5
particular circumstances of Kimbrough’s case and accorded weight to the Sentencing

Commission’s consistent and emphatic position that the crack/powder disparity is at

odds with § 3553(a).”

. 
Accordingly, the Court held that the district court

did not abuse its discretion in calculating Kimbrough’s sentence, and the Fourth

Circuit erred in concluding otherwise.
 Id.

      Begay draws several 
comparisons between the crack/powder disparity

addressed by the Court in Kimbrough and the disparity in aggravated-assault

sentences imposed on Native Americans. Like the crack/powder disparity, the

aggravated-assault disparity originates in a statute: the 1885 Major Crimes Act

(“MCA”), 18 U.S.C. § 1153, which confers exclusive jurisdiction to the federal

courts over certain offenses committed by “[a]ny Indian . . . within the Indian

country.” As Begay contends, and the government does not dispute, the MCA

disproportionately affects Native Americans.

      Also like the crack/powder disparity, the aggravated-assault disparity is not the

result of empirical data or national experience. Begay avers that the Sentencing

Commission failed to collect adequate demographic data when it decided to apply the

Guidelines to the MCA. As a result, the Commission did not consider the potentially

disproportionate impact the Guidelines would have on Native Americans convicted

of crimes enumerated in the statute. Acknowledging this problem, the Commission

formed two advisory groups, the Native American Advisory Group (“NAAG”) and

the Tribal Issues Advisory Group (“TIAG”), to improve the application of the

Guidelines to Native Americans under the MCA. The advisory groups confirmed the

                                             6
disparity between federal and state sentences imposed on Native Americans—

particularly aggravated-assault sentences in New Mexico. See U.S. Sentencing

Comm’n, Report of the Native American Advisory Group i (2003); U.S. Sentencing

Comm’n, Report of the Tribal Issues Advisory Group 3, 19 (2016).



                                           B

      Before the district court, Begay argued these similarities with Kimbrough

warranted consideration in the calculation of his sentence. Relying on our

unpublished decision in Beaver, 749 F. App’x 742, the district court concluded that it

could not consider disparities in aggravated-assault sentences imposed in federal

court versus New Mexico state court. Beaver, of course, is not precedential, but it

nonetheless purports to rely on two opinions, United States v. Branson, 
463 F.3d

1110 
(10th Cir. 2006), and United States v. Wiseman, 
749 F.3d 1196 
(10th Cir.

2014), for its stated proposition. 749 F. App’x at 748. On appeal, Begay argues we

should consider federal/state sentencing disparities that disproportionately affect

Native Americans, drawing compelling parallels to the application of the

crack/powder disparity on African Americans discussed in Kimbrough.

      In Branson, we rejected the argument that a sentencing court must take

account of federal/state sentencing disparities under § 
3553(a)(6). 463 F.3d at 1112
.

That subsection provides that sentencing courts must consider “the need to avoid

unwarranted sentence disparities among defendants with similar records who have

been found guilty of similar conduct.” § 3553(a)(6). We explained in Branson that

                                           7
this directive “does not mean that a sentence calculated under the Guidelines is

unreasonable simply because it is harsher than a state-court sentence would be for a

comparable 
crime.” 463 F.3d at 1112
. Because state and federal courts exercise

concurrent jurisdiction over several criminal offenses, differences in sentences

imposed in state and federal courts are to be expected. See
 id. Thus, consistent with
the rulings of our sibling circuits, we concluded that the purpose of § 3553(a)(6) is

not to prevent disparities between state and federal sentences, but rather to prevent

disparities in sentences among federal defendants.
 

2-13 
(collecting cases).

Were the sentencing court to conform a federal sentence to a state sentence, it would

undermine this goal. See
 id. at 1112. 
Accordingly, we held that “[t]he sentence

imposed on Mr. Branson is not unreasonable simply because it is more severe than a

state-court sentence would have been.”
 

3 
(emphasis added).

      Eight years later in Wiseman, we again rejected the argument that the district

court procedurally erred by failing to consider, under § 3553(a)(6), whether the

defendant would have received a different sentence in state court for similar 
conduct.

749 F.3d at 1194
, 1196. Citing Branson, we affirmed “that § 3553(a)(6) is only

intended to apply to sentencing disparity among and between similarly situated

federal defendants.”
 Id. at 1196 
(citation omitted). We further concluded that under

Kimbrough, a “judge’s policy judgment that drug sentences in federal court are too

long when compared to state court sentences” cannot be used as the basis for a

downward variance under § 3553(a)(6).
 Id.



                                           8
      We are sympathetic to Begay’s concern that Native Americans receive harsher

sentences for aggravated assault than other groups for no reason other than Native

Americans are disproportionately subject to federal criminal jurisdiction.

Nevertheless, we acknowledge “[w]e cannot overrule the judgment of another panel of

this court. We are bound by the precedent of prior panels absent en banc reconsideration

or a superseding contrary decision by the Supreme Court.” In re Smith, 
10 F.3d 723
, 724

(10th Cir. 1993) (per curiam). Branson and Wiseman control, and they preclude

consideration of Begay’s sentencing-disparity arguments.

      These precedents deal only with § 3553(a)(6). Begay’s sentencing-disparity

arguments may be relevant to other § 3553(a) factors. See 
Kimbrough, 552 U.S. at

110-11
.1 We agree with the government, however, that Begay has failed to

sufficiently develop his arguments with respect to any § 3553(a) factor other than

§ 3553(a)(6). In his opening brief on appeal, Begay cites the provision in

§ 3553(a)(2)(A) that requires a district court to consider “the need for the sentence

imposed . . . to promote respect for the law.” But other than a citation to a dissenting



      1
        We note that in Kimbrough, the Court specifically upheld the district court’s
application of the § 3553(a) factors to the crack/powder sentencing disparity,
including its allusion to the Sentencing Commission’s reports on the 100-to-1
disparity under § 3553(a)(5), which requires consideration of policy statements
issued by the Sentencing Commission.
 Id. at 110. 
The Court also approved the
sentencing court’s “fram[ing of] its final determination in line with § 3553(a)’s
overarching instruction to impose a sentence sufficient, but not greater than
necessary, to accomplish the sentencing goals advanced in § 3553(a)(2).”
 Id. at 111
(quotation omitted); see also 
Wiseman, 749 F.3d at 1196 
(noting possibility that
sentencing disparity could warrant downward variance under § 3553(a) factors other
than § 3553(a)(6)).
                                           9
opinion from one of our sibling circuits and a citation to Kimbrough, he does not

further develop the argument that a district court may consider a federal/state

sentencing disparity under § 3553(a)(2)(A). Accordingly, we consider Begay’s

sentencing-disparity arguments under only § 3553(a)(6).

      So limited, Begay’s arguments are foreclosed by Branson and Wiseman. Both

cases squarely hold that a district court may not consider a federal/state sentencing

disparity under § 3553(a)(6), reasoning that consideration of such a disparity would

undermine the statute’s goal of achieving uniformity in sentences among similarly

situated federal defendants. 
Branson, 463 F.3d at 1112-13
; 
Wiseman, 749 F.3d at

1196
. Wiseman, moreover, holds that “the Kimbrough line of cases do not . . .

conflict with Branson” and do not contradict our interpretation of § 
3553(a)(6). 749

F.3d at 1195
. Instead, Kimbrough recognizes “that the guidelines are advisory and

that district courts have the authority to deviate from guideline sentences based on

policy considerations, including disagreements with the guidelines.”
 Id. Begay

attempts to 
distinguish Branson and Wiseman on the basis that they did not involve a

Native American defendant. But the disproportionate effect of a sentencing disparity

on Native Americans, though perhaps relevant to other § 3553(a) factors, does not

permit us to review federal/state disparities under § 3553(a)(6).2


      2
         Begay also argues that his sentence is substantively unreasonable because the
district court “failed to recognize [that] federal/state sentencing disparities warranted
a place in its sentencing deliberation.” His argument for substantive
unreasonableness is substantially identical to his arguments for procedural
unreasonableness. Because he contends the district court failed to consider his
sentencing-disparity arguments under the § 3553(a) sentencing factors, Begay’s
                                           10
                                           III

      AFFIRMED.




substantive-unreasonableness argument is properly addressed as a challenge to the
procedural reasonableness of his sentence. See United States v. Sanchez-Leon, 
764
F.3d 1248
, 1268 n.15 (10th Cir. 2014) (“[P]rocedural error is the failure to consider
all the relevant factors, whereas substantive error is when the district court imposes a
sentence that does not fairly reflect those factors.” (alterations and quotations
omitted)). Accordingly, we reject his substantive-unreasonableness challenge.
        Additionally, Begay argues in a footnote that “the issue raised in this case is
tantamount to an equal protection violation as it raises . . . concerns of injustice based
on immutable characteristics.” He provides no further explanation in support of this
assertion. Because this argument is insufficiently developed, we decline to consider
it. See Bronson v. Swensen, 
500 F.3d 1099
, 1104 (10th Cir. 2007) (issues omitted
from or inadequately presented in opening brief are waived).
                                           11