United Mexican States v. Lion Mexico Consolidated L.p.

United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT
Argued November 3, 2025 Decided April 7, 2026
No. 24-7185
UNITED M EXICAN S TATES ,
APPELLANT
v.
LION M EXICO C ONSOLIDATED L.P.,
APPELLEE
HECTOR C ARDENAS ,
M OVANT-APPELLANT
Consolidated with 24-7186
Appeals from the United States District Court
for the District of Columbia
(No. 1:21-cv-03185)
Stephan E. Becker argued the cause for appellant United
Mexican States. With him on the briefs was Gary J. Shaw.
Luis A. Parada argued the cause for movant-appellant
Hector Cardenas. With him on the briefs was Csaba M.
Rusznak.

-- 1 of 18 --

2
John M. Conlon argued the cause for appellee. With him
on the briefs was Kevin B. Weehunt Jr. Reginald R. Goeke
entered an appearance.
Before: P ILLARD , WALKER and C HILDS , Circuit Judges.
Opinion for the Court filed by Circuit Judge P ILLARD.
P ILLARD, Circuit Judge: Mexico seeks to vacate an
arbitration award resolving an investment dispute between
Mexico and Lion Mexico Consolidated, a Canadian investor.
Applying provisions of the North American Free Trade
Agreement, a panel of arbitrators ordered Mexico to pay Lion
$47 million in compensation for the country’s failure to protect
the company’s investments in real estate projects in Mexico.
Mexico petitioned our district court to vacate the arbitral award
on the grounds that the arbitrators exceeded their powers and
acted in manifest disregard of the law. The district court held
the arbitrators acted within their authority and with appropriate
regard for the law, so denied Mexico’s petition and granted the
investor’s cross-petition for confirmation of the award.
Mexico appeals. Separately, Héctor Cárdenas Curiel, a
Mexican businessman involved in the events that gave rise to
the arbitration, moved to intervene in the district court
proceedings. The district court denied intervention, and
Cárdenas appeals. We affirm in full.
I.
A.
The North American Free Trade Agreement (NAFTA)
was a multilateral treaty between the United States of America,
Mexico, and Canada that sought to facilitate trade and

-- 2 of 18 --

3
economic activity, including cross-border investment, among
the three nations. North American Free Trade Agreement, Dec.
17, 1992, 107 Stat. 2057, 32 I.L.M. 289. NAFTA is no longer
in effect since it was superseded on July 1, 2020, by the U.S.-
Mexico-Canada Agreement. See United States-Mexico-
Canada Agreement Implementation Act, Pub. L. No. 116-113,
134 Stat. 11 (2020). But the arbitration at issue here, instituted
in December 2015, was governed by NAFTA, and NAFTA’s
intervening repeal has no effect on its applicability to this
dispute.
Among NAFTA’s provisions to encourage cross-border
investment—memorialized in Chapter 11 of NAFTA—was the
requirement that each party “accord to investments of investors
of another Party treatment in accordance with international
law, including fair and equitable treatment and full protection
and security.” NAFTA art. 1105(1). NAFTA allowed foreign
investors to initiate arbitration proceedings directly against a
party government for violating the protections of Chapter 11,
including Article 1105(1). See id. art. 1120(1). The treaty
established the Free Trade Commission, an entity comprising
the trade ministers of the three NAFTA signatories, to
supervise its implementation and interpretation. The
Commission’s interpretations of NAFTA bound any arbitral
tribunal convened to adjudicate a dispute under the treaty. Id.
arts. 1131(2), 2001(1).
A petition in United States court to confirm an arbitral
award based on a treaty to which the United States is a party
may proceed under the Federal Arbitration Act (FAA), 9
U.S.C. § 1 et seq., which recognizes such a treaty as federal
law, id. at § 201. See, e.g., BG Grp. PLC v. Rep. of Argentina,
572 U.S. 25, 44 (2014); LLC SPC Stileks v. Republic of
Moldova, 985 F.3d 871, 879 n.2 (D.C. Cir. 2021). The FAA
establishes a “federal policy favoring arbitration” and requires

-- 3 of 18 --

4
federal courts to “rigorously enforce agreements to arbitrate.”
Shearson/Am. Express, Inc. v. McMahon, 482 U.S. 220, 226
(1987) (internal quotation marks omitted). Limited judicial
review protects the “prime objective” of an agreement to
arbitrate, which is “to achieve ‘streamlined proceedings and
expeditious results.’” Preston v. Ferrer, 552 U.S. 346, 357
(2008) (quoting Mitsubishi Motors Corp. v. Soler Chrysler-
Plymouth, Inc., 473 U.S. 614, 633 (1985)). Judicial power to
vacate arbitral decisions is accordingly confined to “very
unusual circumstances.” Oxford Health Plans LLC v. Sutter,
569 U.S. 564, 568 (2013) (quoting First Options of Chicago,
Inc. v. Kaplan, 514 U.S. 938, 942 (1995)). The FAA lists four
grounds on which a court may vacate an arbitration award. See
9 U.S.C. § 10(a). At issue in this case is the fourth ground:
“where the arbitrators exceeded their powers.” Id.
A party seeking vacatur of an arbitral award on the ground
that the arbitrators “exceeded their powers” bears a “heavy
burden.” Oxford Health Plans, 569 U.S. at 569. It is not
enough for the challenger to show that the arbitrators
“committed an error—or even a serious error.” Stolt-Nielsen
S.A. v. AnimalFeeds Int’l Corp., 559 U.S. 662, 671 (2010).
Because the parties “bargained for the arbitrator’s construction
of their agreement,” an arbitral award “even arguably
construing or applying the contract” will stand, “regardless of
a court’s view of its (de)merits.” Oxford Health Plans, 569
U.S. at 569 (internal quotation marks omitted). Only when
arbitrators exceed the scope of their delegated authority by
“issuing an award that simply reflects [their] own notions of
economic justice rather than drawing its essence from the
contract” will the arbitrators’ decision be set aside. Oxford
Health Plans, 569 U.S. at 569 (formatting modified). Thus,
“the sole question” for a court entertaining a petition for relief
under Section 10(a)(4) is “whether the arbitrator (even

-- 4 of 18 --

5
arguably) interpreted the parties’ contract, not whether [they]
got its meaning right or wrong.” Id.
B.
Lion Mexico Consolidated, L.P. (Lion) is a Canadian
company that made loans to companies owned by a Mexican
businessman named Héctor Cárdenas Curiel (Cárdenas) to
finance real estate projects in Mexico. United Mexican States
v. Lion Mexico Consolidated, L.P., 757 F. Supp. 3d 18, 23
(D.D.C. 2024). The parties documented the loans through
mortgages to Lion on the real property and promissory notes to
Lion as unconditional commitments to repay the loans. Id.; see
Arbitration Award (Award), Annex A (Decision on
Jurisdiction) ¶ 58 (J.A. 252). Cárdenas’s companies, however,
never made a single payment on the loans. United Mexican
States, 757 F. Supp. 3d at 23. After Lion’s fruitless efforts to
recoup its investment through direct negotiation with Cárdenas
and litigation in Mexican courts that Cárdenas stymied, Lion
initiated arbitration proceedings against the government of
Mexico in December 2015. Award ¶ 12 (J.A. 37).
The arbitration was seated in Washington D.C. Id. ¶ 40
(J.A. 40). As relevant here, Lion claimed that Mexico had
failed to grant its loan-based investments the protections
required by Article 1105(1) of NAFTA. See Award ¶ 187 (J.A.
76). Lion contended that Article 1105(1) protected each form
of financing that it had provided to Cárdenas’s companies: the
mortgages and the promissory notes. See United Mexican
States, 757 F. Supp. 3d at 29. In response, Mexico objected
that the arbitral tribunal (Tribunal) lacked jurisdiction over
Lion’s Article 1105(1) claims because neither the mortgages
nor the promissory notes qualified as “investments” as that
term was defined in NAFTA. See Decision on Jurisdiction ¶ 98
(J.A. 260). Mexico further contended that, even if Lion had

-- 5 of 18 --

6
made qualifying “investments,” Lion could not obtain relief
because Article 1105(1) protected only investments and not
investors. Mexico’s Counter Memorial ¶ 141 (J.A. 322).
On September 9, 2021, the Tribunal handed down its
award in Lion’s favor. The Tribunal found that when Lion tried
to recoup its investments in the Mexican courts, Cárdenas
orchestrated a scheme of “complex judicial fraud” to frustrate
any recovery. Award ¶ 94 (J.A. 51). Specifically, the Tribunal
found that a Mexican court judgment purporting to cancel
Lion’s loans to Cárdenas’s companies rested on a forged
settlement agreement Cárdenas had prepared. Id. ¶¶ 94-95,
103 (J.A. 51-52, 54). The Tribunal further found that, despite
Lion’s repeated attempts to establish that the putative
agreement undergirding the apparent cancellation judgment
had been forged, Lion obtained no relief from the Mexican
courts. See id. ¶¶ 138-79 (J.A. 63-72); United Mexican States,
757 F. Supp. 3d at 23-25.
Based on those findings, the Tribunal determined that
Mexico breached its Article 1105 obligations to Lion. Award
¶ 354 (J.A. 110). As a threshold matter, the Tribunal concluded
that it had jurisdiction over Lion’s Article 1105 claims as to the
mortgages, but not as to the promissory notes, because only the
former qualified as “investments” under NAFTA. Decision on
Jurisdiction ¶ 266 (J.A. 293). On the merits, the Tribunal
concluded that Article 1105(1) “protects investments and
investors,” rejecting Mexico’s argument that the provision
“only extends protection to investments, but not to investors.”
Award ¶ 356 (J.A. 110). And Mexico breached its Article
1105(1) obligations to Lion because Mexico’s courts
repeatedly failed to provide Lion a fair opportunity, consistent
with the “customary international law minimum standard of
treatment of aliens,” to vindicate its rights to its investments.
Id. ¶¶ 210, 299, 506-509 (J.A. 81, 98, 138). The Tribunal

-- 6 of 18 --

7
consequently ordered Mexico to pay Lion $47 million in
compensation, plus costs and attorney’s fees. Id. ¶ 851 (J.A.
216).
C.
On December 6, 2021, Mexico petitioned the United
States District Court for the District of Columbia to vacate the
award on the grounds that the Tribunal “exceeded [its] powers”
under 9 U.S.C. § 10(a)(4) and acted in manifest disregard of
the law. United Mexican States, 757 F. Supp. 3d at 27, 32.
Specifically, Mexico argued that the Tribunal had
impermissibly expanded the scope of Article 1105(1) by
entering an award that protected foreign investors—not just
investments—in Mexico. Id. at 29. Lion opposed the petition
and submitted a cross-petition for confirmation of the award.
Id. at 27.
The district court denied Mexico’s petition and granted
Lion’s. Id. at 33. The court first corrected what it viewed as
Mexico’s fundamental misapprehension of the Tribunal’s
ruling: that the Tribunal had interpreted Article 1105(1) to
generally protect foreign investors from unfair or inequitable
treatment, even when the mistreatment was unconnected to any
“investments” protected under NAFTA. Id. at 29. The district
court explained that such a “sweeping” understanding of the
Tribunal’s decision could not be squared with the award’s
reasoning, including the Tribunal’s dismissal of Lion’s claims
as to the promissory notes for failure to qualify as
“investments” under NAFTA. Id. Thus, the district court
explained, the Tribunal interpreted Article 1105(1) to protect
foreign investors only from unfair treatment that adversely
affects their qualifying investments.
The court then determined that the Tribunal did not exceed
its powers in so concluding because the Tribunal’s work fell

-- 7 of 18 --

8
“comfortably within the realm of interpretation.” Id. at 30. The
court explained that the award reflected the Tribunal’s
interpretation because it “identified and rejected Mexico’s
argument, applied existing guidance interpreting Article
1105(1), cited cases, and explained its reasoning.” Id. Next,
assuming without deciding that arbitrators’ “manifest disregard
of the law” could provide an alternative, non-statutory basis for
vacating an arbitral award, the court concluded that the
Tribunal’s award could not be so characterized for largely the
same reasons the Tribunal did not exceed its powers in entering
it. Id. at 28 n.8, 32. The court thus saw nothing warranting
vacatur of the award. Id. at 32. Because a court “must grant”
a timely filed petition to confirm an arbitral award “unless the
award is vacated, modified, or corrected as prescribed in
[S]ections 10 and 11 of [the FAA],” the district court granted
Lion’s timely cross-petition for confirmation. Id. at 32-33
(quoting 9 U.S.C. § 9).
Separately, while the petition and cross-petition remained
pending in the district court but five months after the parties
had finished their briefing, Cárdenas moved to intervene. Id.
at 27. The arbitrators had found that Cárdenas orchestrated the
fraudulent scheme in the Mexican courts that harmed Lion.
Claiming that the award had violated his due process rights by
“ma[king] serious findings of unlawful conduct against him
during the arbitration without affording him an opportunity” to
defend himself, Cárdenas sought to intervene in the district
court in support of Mexico’s petition to vacate the award.
United Mexican States v. Lion Mex. Consol. LP, No. 21-3185
(D.D.C. July 21, 2023), ECF No. 42-1 (Mem. ISO Mot. to
Intervene) at 13. He claimed his intervention would present an
argument in support of vacatur that Mexico had not raised. Id.
In the same order in which it denied Mexico’s petition, the
district court denied Cárdenas’s motion to intervene: Cárdenas
failed to establish that he is entitled to intervene as of right,

-- 8 of 18 --

9
Fed. R. Civ. P. 24(a)(2), and provided no basis for permissive
intervention, Fed. R. Civ. P. 24(b). United Mexican States, 757
F. Supp. 3d at 33-37.
Mexico and Cárdenas each timely appealed.
II.
We begin with Mexico’s petition to vacate the arbitral
award. We review de novo the district court’s application of
the highly circumscribed grounds for vacatur. Selden v.
Airbnb, Inc., 4 F.4th 148, 155 (D.C. Cir. 2021).
A.
Mexico first contends that the award should be vacated
because the Tribunal “exceeded [its] powers.” 9 U.S.C.
§ 10(a)(4). We are unpersuaded. As already noted, in
reviewing a petition to vacate an arbitral award under Section
10(a)(4) of the FAA, “the sole question for us is whether the
arbitrator (even arguably) interpreted the parties’ contract”—
or, in this case, the treaty—“not whether he got its meaning
right or wrong.” Oxford Health Plans, 569 U.S. at 569. If the
arbitrator even arguably interpreted the terms of the agreement
to arbitrate, the petition must be denied. Id. Here, Mexico
challenges the Tribunal’s conclusion that Article 1105(1)
protects investors with regards to their qualifying investments.
Thus, the question is whether the Tribunal arguably interpreted
Article 1105(1) in so concluding. We conclude that it did.
Describing the Tribunal’s analysis proves the point. In
determining that Article 1105(1) covers investors as to their
protected investments, the Tribunal started, as interpreters of
law routinely do, with the text of that provision. See Award
¶ 356 (J.A. 110). The key Article states: “Each Party shall
accord to investments of investors of another Party treatment

-- 9 of 18 --

10
in accordance with international law . . . .” NAFTA art.
1105(1). The Tribunal noted that the “literal” terms of Article
1105(1) referenced the “treatment” of “investments of
investors,” Award ¶ 356 (J.A. 110), so it looked to authorities
interpreting those terms.
First, the Tribunal relied on a Free Trade Commission
Interpretation Note from July 31, 2001. In the Interpretation
Note, the Commission understood Article 1105(1) as
prescribing “the customary international law minimum
standard of treatment of aliens” as the minimum standard of
treatment to be afforded to investments of investors of another
party. Award ¶¶ 356-58 (J.A. 110) (emphasis added) (internal
quotation marks omitted). Because in the context of foreign-
investor protection the Interpretation Note’s reference to
“aliens” could “only mean investors,” id. ¶ 358 (J.A. 110), and
because NAFTA makes the Commission’s Interpretation Notes
binding on arbitral tribunals adjudicating claims under that
treaty, see NAFTA art. 1131(2), the Tribunal concluded that it
was bound to interpret Article 1105(1) to protect investors,
Award ¶ 358 (J.A. 110). The Tribunal then relied on several
arbitration decisions that had “construed Art. 1105 as a source
of protection for investors rather than solely for their
investments.” Id. ¶ 358 & n.384 (J.A. 110).
Starting with the text of Article 1105(1) and giving
meaning to that text in accord with binding and persuasive
authorities interpreting it, the Tribunal’s analysis is, “through
and through, [an] interpretation[] of the parties’ agreement.”
Oxford Health Plans, 569 U.S. at 570. Contrary to Mexico’s
contentions, this is not a case in which the Tribunal lacked “any
contractual basis” for its conclusion, such that the Tribunal
“simply imposed its own conception of sound policy.” Id. at
571 (internal quotation marks omitted); cf. Raymond James
Fin. Servs., Inc. v. Bishop, 596 F.3d 183, 189 (4th Cir. 2010)

-- 10 of 18 --

11
(vacating arbitral award that either “disregarded or modified
unambiguous contract provisions” or was based on arbitrators’
“own personal notions of right and wrong”); Mo. River Servs.,
Inc. v. Omaha Tribe of Neb., 267 F.3d 848, 855 (8th Cir. 2001)
(vacating arbitral award that “rewrote” the contract (internal
quotation marks omitted)).
Mexico levies two challenges to the contrary. It first
contends that the district court “definitively” recognized that
Article 1105(1) unambiguously excluded investors, yet its
opinion and order impermissibly “ignored its previous
finding.” Mex. Br. 20, 22. As an initial matter, any such
determination by the district court on the meaning of Article
1105(1)—a legal interpretation that Mexico inaccurately
characterizes as a “finding”—would not bind us on de novo
review. The district court, moreover, never concluded that
Article 1105(1) unambiguously excluded investors. Mexico
cites the district court’s statement, made while questioning
counsel at oral argument, that “a literal reading of 1105(1)
clearly does not apply to investors.” See Mex. Br. 20-21. But,
as the district court ultimately concluded, the Tribunal’s
holding that Article 1105(1) protects investors still fell
comfortably within the realm of interpretation. United
Mexican States, 757 F. Supp. 3d at 29-31. Indeed, as the
Tribunal’s interpretation of Article 1105(1) illustrates, an
observation about a “literal” reading is not the same thing as
arriving at an “unambiguous” interpretation. Ultimately,
whether Article 1105(1) is ambiguous (and whether the district
court so concluded) is relevant only insofar as it bears on
whether the Tribunal interpreted Article 1105(1) in rendering
its award—which the Tribunal plainly did.
Mexico also argues that the district court erred by
inaccurately “refram[ing]” the issue addressed by the Tribunal
as one of “standing.” See Mex. Br. 28-30. But the district

-- 11 of 18 --

12
court did not so “reframe” the issue. When the court said that
“[t]he Tribunal held only that investors had standing to bring
claims if a challenged action affected a qualified investment,”
it was simply restating its observation that the Tribunal did not
“rule that Article 1105(1) applied to investors writ large,” but
“only that an investor could bring a claim under Article 1105(1)
if the challenged treatment affected a qualifying investment”
by that investor. United Mexican States, 757 F. Supp. 3d at 29.
What matters for judicial review is that the Tribunal arrived at
that understanding by interpreting Article 1105(1). And, for
reasons well explained by the district court, that is the best
reading of how the Tribunal understood Article 1105(1). See
id. at 29-31.
In sum, Mexico has failed to carry its “heavy burden” to
show that the Tribunal exceeded its authority in concluding that
Article 1105(1) protected Lion with regard to its investments.
Oxford Health Plans, 569 U.S. at 569.
B.
As an alternative ground for vacatur, Mexico contends that
the Tribunal acted in manifest disregard of the “governing law
of treaty interpretation” as expressed in Article 31 of the
Vienna Convention on the Law of Treaties. Mex. Br. 30
(formatting modified). We disagree.
It is “unclear . . . whether manifest disregard remains a
valid ground for vacatur after the Supreme Court’s decision in
Hall Street Associates v. Mattel, Inc., 552 U.S. 576, 584-86
(2008),” which held that “the FAA’s list of grounds for
refusing to enforce an award is exclusive.” Selden, 4 F.4th at
160 n.6. The Supreme Court and this court have yet to decide
whether non-statutory grounds for vacatur, including manifest
disregard of the law, survived Hall Street. Stolt-Nielsen S.A.,
559 U.S. at 672 n.3; Metro. Mun. of Lima v. Rutas De Lima

-- 12 of 18 --

13
S.A.C., 141 F.4th 209, 219 (D.C. Cir. 2025). And we need not
decide that question here. Even assuming, as the district court
did, that manifest disregard of the law remains a separate
ground for vacatur, the Tribunal did not act in manifest
disregard of the law.
The party seeking to vacate an arbitral award bears the
burden of demonstrating that the arbitrators acted in manifest
disregard of the law. LaPrade v. Kidder, Peabody & Co., 246
F.3d 702, 706 (D.C. Cir. 2001). We have ruled that a tribunal
acts in manifest disregard of the law if “(1) the arbitrators knew
of a governing legal principle yet refused to apply it or ignored
it altogether;” and (2) “the law ignored by the arbitrators was
well defined, explicit, and clearly applicable to the case.” Id.
(internal quotation marks omitted). Consistent with the
deference owed to arbitrators’ judgments and the finality
interests that arbitration is designed to serve, we treat manifest
disregard as an “extremely narrow” standard of review that is
unmet “if any justification” for an award “can be gleaned from
the record.” Kurke v. Oscar Gruss & Son, Inc., 454 F.3d 350,
354 (D.C. Cir. 2006) (internal quotation marks omitted).
Mexico fails to demonstrate that the Tribunal acted in
manifest disregard of the law in interpreting Article 1105(1) to
protect Lion with respect to its qualifying investments.
Assuming that Article 31 of the Vienna Convention on the Law
of Treaties constitutes a “governing legal principle” that is
“well defined, explicit, and clearly applicable to the case,”
within the meaning of the manifest-disregard principle, Mexico
has not shown that the Tribunal “refused to apply it or ignored
it altogether.” LaPrade, 246 F.3d at 706 (internal quotation
marks omitted).
Article 31 of the Vienna Convention provides the
“[g]eneral rule of interpretation” for construing treaties.

-- 13 of 18 --

14
Vienna Convention on the Law of Treaties art. 31, May 23,
1969, 1155 U.N.T.S. 331 (Vienna Convention). It instructs
that “[a] treaty shall be interpreted in good faith in accordance
with the ordinary meaning to be given to the terms of the treaty
in their context and in the light of its object and purpose.” Id.
Mexico places great emphasis on Article 31’s reference to the
“ordinary meaning” of the treaty, which it says “requires fealty
to the text.” Mex. Br. 32. And because the text of Article
1105(1) of NAFTA only refers to “investments of investors”
and not “investors,” Mexico contends that the Tribunal acted
in manifest disregard of its obligation to interpret the treaty
according to its “ordinary meaning.” Id. at 34.
But Article 31 does not say that a treaty’s interpretation
must end with the text. Rather, it instructs that “ordinary
meaning” is “to be given to the terms of the treaty in their
context and in the light of its object and purpose.” Vienna
Convention art. 31. Mexico interprets Article 1105(1) of
NAFTA to protect only “investments” and not “investors,”
such that it provides no protection to investors whose
investments are mistreated. That interpretation, as the district
court explained, would undermine “NAFTA’s purpose of
encouraging the free flow of goods, services, and investments
among the signatories.” United Mexican States, 757 F. Supp.
3d at 31 (citing NAFTA art. 102(1)).
Moreover, Article 31 also requires interpreters to “take[]
into account” “any subsequent agreement between the parties
regarding the interpretation of the treaty or the application of
its provisions.” Vienna Convention art. 31. Here, as explained
above, Article 1131(2) of NAFTA required the Tribunal to treat
the Free Trade Commission’s Interpretation Notes as binding.
The Tribunal faithfully complied with Article 1131(2) of
NAFTA—and thus, Article 31 of the Vienna Convention—
when it considered the Free Trade Commission’s Interpretation

-- 14 of 18 --

15
Note on Article 1105(1). And that Interpretation Note supports
the Tribunal’s interpretation of Article 1105(1) to protect
investors with regard to their qualifying investments. See
supra at 10; see also United Mexican States, 757 F. Supp. 3d
at 26-27. For these reasons, the Tribunal did not “refuse[] to
apply” or “ignore . . . altogether” Article 31 of the Vienna
Convention. LaPrade, 246 F.3d at 706 (internal quotation
marks omitted). Accordingly, Mexico has not shown that the
Tribunal acted in manifest disregard of the law.
Because Mexico failed to carry its burden to show that the
Tribunal “exceeded [its] powers,” 9 U.S.C. § 10(a)(4), or acted
in manifest disregard of the law, LaPrade, 246 F.3d at 706, we
affirm the district court’s order denying Mexico’s petition to
vacate the arbitral award and granting Lion’s cross-petition for
confirmation.
III.
We next address the district court’s denial of Cárdenas’s
motion to intervene. Reviewing for abuse of discretion,
Campaign Leg. Ctr. v. Fed. Election Comm’n, 68 F.4th 607,
610 (D.C. Cir. 2023), we affirm.
Cárdenas first argues that he was entitled to intervene as
of right under Federal Rule of Civil Procedure 24(a)(2).
“Parties have the right under Rule 24(a)(2) to intervene in an
action if they meet four requirements: (1) the application to
intervene must be timely; (2) the applicant must demonstrate a
legally protected interest in the action; (3) the action must
threaten to impair that interest; and (4) no party to the action
can be an adequate representative of the applicant’s interests.”
SEC v. Prudential Sec. Inc., 136 F.3d 153, 156 (D.C. Cir.
1998). The district court denied intervention as of right for
three reasons: First, Cárdenas’s motion was not timely; second,
Cárdenas’s motion would have been futile; and third, Mexico

-- 15 of 18 --

16
could adequately represent Cárdenas’s interest. United
Mexican States, 757 F. Supp. 3d at 33-36.
Because Mexico’s ability to adequately represent
Cárdenas’s interest suffices to defeat intervention as of right,
we need not consider the district court’s other reasons. In his
brief to us, Cárdenas says he is “not seeking to intervene in the
vacatur proceeding to challenge the fraud findings or to try to
reopen the other factual findings by the tribunal.” Cárdenas Br.
31 (formatting modified). Instead, he seeks to intervene only
“in support of Mexico’s petition to vacate an arbitral award that
directly harms his interests, by making additional arguments in
support of vacatur that Mexico did not make.” Id. Even
assuming that Cárdenas has a cognizable interest in seeking
vacatur of the award, Cárdenas does not contest that the interest
he seeks to protect by intervening—to vacate the entire award
rather than challenge specific findings about himself—is the
same as Mexico’s. Cárdenas Br. 42. Thus, as the district court
explained, Cárdenas’s motion “at best reflects a strategy
disagreement with Mexico” about which arguments to raise in
support of the shared goal of vacatur. United Mexican States,
757 F. Supp. 3d at 36. That kind of disagreement about
litigation strategy does “not make inadequate the
representation of those whose interests are identical with that
of an existing party.” Jones v. Prince George’s Cnty., 348 F.3d
1014, 1020 (D.C. Cir. 2004) (internal quotation marks
omitted). Thus, Mexico could adequately represent Cárdenas’s
interest, which is an independently sufficient reason to deny
intervention as of right. See Fed. R. Civ. P. 24(a)(2).
Cárdenas alternatively contends that the district court
should have allowed him permissive intervention under Rule
24(b)(1). A court “may” allow intervention under Rule
24(b)(1) if the would-be intervenor presents “(1) an
independent ground for subject matter jurisdiction; (2) a timely

-- 16 of 18 --

17
motion; and (3) a claim or defense that has a question of law or
fact in common with the main action.” E.E.O.C. v. Nat’l
Children’s Ctr., Inc., 146 F.3d 1042, 1046 (D.C. Cir. 1998).
Even when a movant meets those criteria, a court retains
discretion to deny intervention. Id. The district court
concluded that Cárdenas did not satisfy the criteria for
permissive intervention because his motion was untimely, and
that in any event his intervention would be “unlikely to
significantly contribute to . . . the just and equitable
adjudication of the legal question presented.” United Mexican
States, 757 F. Supp. 3d at 37 (internal quotation marks
omitted).
The district court acted within its sound discretion in
denying permissive intervention under Rule 24(b)(1). Even if
Cárdenas had timely sought intervention, the district court, in
exercising its discretion, would have had to consider whether
the intervention would “unduly delay or prejudice the
adjudication of the original parties’ rights.” Fed. R. Civ. P.
24(b)(3). And, as the court correctly explained, allowing
Cárdenas to intervene would have “delay[ed] the
proceeding . . . by requiring the parties to dedicate substantial
time and resources briefing arguments” that both parties agreed
were “unrelated to the existing petitions.” United Mexican
States, 757 F. Supp. 3d at 35. In these circumstances, the
district court did not abuse the “wide latitude afforded to
district courts” under Rule 24(b) when it denied Cárdenas’s
motion for permissive intervention. National Children’s Ctr.,
146 F.3d at 1046.
We thus affirm the district court’s denial of Cárdenas’s
motion to intervene.

-- 17 of 18 --

18
* * *
For the foregoing reasons, we affirm the district court’s
order.
So ordered.

-- 18 of 18 --