Full opinion text
Opinion for the court filed by Circuit Judge HENDERSON. Concurring opinion filed by Circuit Judge HENDERSON. Opinion concurring in the judgment in part and dissenting filed by Circuit Judge ROGERS. Opinion concurring in the judgment in part and dissenting in part filed by Circuit Judge BROWN. Opinion concurring in the judgment in part and dissenting in part filed by Circuit Judge KAVANAUGH. On Petition for Rehearing En Banc KAREN LeCRAFT HENDERSON, Circuit Judge: Ali Hamza Ahmad Suliman al Bahlul (Bahlul) served as a personal assistant to Osama bin Laden, produced propaganda videos for al Qaeda and assisted with preparations for the attacks of September 11, 2001 that killed thousands of Americans. Three months after 9/11, Bahlul was captured in Pakistan and transferred to the United States Naval Base at Guantanamo Bay, Cuba. Military prosecutors charged him with three crimes: conspiracy to commit war crimes, providing material support for terrorism and solicitation of others to commit war crimes. A military commission convicted him of all three crimes and sentenced him to life imprisonment. The United States Court of Military Commission Review (CMCR) affirmed his conviction and sentence. Bahlul appeals. For the reasons that follow, we reject Bahlul’s ex post facto challenge to his conspiracy conviction and remand that conviction to the original panel of this Court for it to dispose of several remaining issues. In addition, we vacate his material support and solicitation convictions. I. Background Bahlul is a native of Yemen. In the late 1990s, he traveled to Afghanistan to join al Qaeda. He completed military-like training while staying at an al Qaeda guesthouse and eventually met and pledged an oath of loyalty (“bayat”) to bin Laden. Bin Laden assigned Bahlul to work in al Qaeda’s media office. On October 12, 2000, al Qaeda suicide bombers attacked the U.S.S. Cole, killing 17 American servicemen and wounding 39 others. Bin Laden later instructed Bahlul to create a video celebrating the attack for use as a recruiting tool. The video Bahlul produced (and bin Laden edited) includes footage of the attack, calls for jihad against the United States and propaganda blaming “Western infidels” and complicit Middle Eastern regimes for Muslim suffering. Bahlul considered it one of the best propaganda videos al Qaeda had produced and it has been translated into several languages and widely distributed. Bin Laden then appointed Bahlul as his personal assistant and secretary for public relations. Bahlul arranged the loyalty oaths of two of the 9/11 hijackers, Mohamed Atta and Ziad al Jarrah, and prepared their “martyr wills”—propaganda declarations documenting al Qaeda’s role in the attacks. Bahlul claims he sought to participate in the 9/11 attacks himself but bin Laden refused because he considered his media man too important to lose. In the days preceding 9/11, Bahlul assembled al Qaeda’s media equipment and evacuated al Qaeda’s Kandahar headquarters with bin Laden and other senior al Qaeda leaders. They traveled to a remote region of Afghanistan where, on September 11, 2001, they heard reports of the day’s attacks via a radio operated by Bahlul. Bin Laden subsequently asked Bahlul to research the economic effects of the attacks and report his findings. In the following weeks, Bahlul fled to Pakistan. He was captured there in December 2001 and turned over to U.S. forces. In 2002, he was transferred to the U.S. Naval Base at Guantanamo Bay, Cuba, where he has since been detained as an enemy combatant pursuant to the 2001 Authorization for Use of Military Force (AUMF). See Pub.L. No. 107-40, § 2(a), 115 Stat. 224, 224; Hamdi v. Rumsfeld, 542 U.S. 507, 518, 521, 124 S.Ct. 2633, 159 L.Ed.2d 578 (2004) (plurality). Two months after 9/11, President Bush invoked the AUMF and Article 21 of the Uniform Code of Military Justice (UCMJ), 10 U.S.C. § 821 (hereinafter “section 821”), to establish military commissions to try “member[s] of ... al Qaida” and others who “engaged in, aided or abetted, or conspired to commit, acts of international terrorism, or acts in preparation therefor.” See Detention, Treatment, and Trial of Certain Non-Citizens in the War Against Terrorism, 66 Fed.Reg. 57,833 (Nov. 13, 2001). In 2003, the President designated Bahlul eligible for trial by military commission and in 2004 military prosecutors charged him with conspiracy to commit war crimes. Bahlul’s prosecution was stayed pending the outcome of another detainee’s challenge to the lawfulness of his trial by military commission. In Hamdan v. Rumsfeld, the United States Supreme Court held that the military commission procedures then in place contravened certain constraints imposed by the UCMJ and the four Geneva Conventions signed in 1949. 548 U.S. 557, 613-35, 126 S.Ct. 2749, 165 L.Ed.2d 723 (2006). In response to the Hamdan decision, the Congress enacted the Military Commissions Act of 2006 (2006 MCA), Pub.L. No. 109-336, 120 Stat. 2600, which amended the statutory procedures governing military commissions to cure the flaws identified in Ham-dan. The 2006 MCA specifically enumerated 30 war crimes triable by military commission, see 10 U.S.C. §§ 950t-950v (2006), and conferred jurisdiction on military commissions to try “any offense made punishable by this chapter or the law of war when committed by an alien unlawful enemy combatant before, on, or after September 11, 2001,” id. § 948d(a). The Supreme Court has long recognized that unlawful enemy combatants may be prosecuted by military commission for their war crimes. See Hamdan, 548 U.S. at 592-98, 126 S.Ct. 2749; Hamdi 542 U.S. at 518, 124 S.Ct. 2633; In re Yamashita, 327 U.S. 1, 7-8, 11, 66 S.Ct. 340, 90 L.Ed. 499 (1946); Ex parte Quirin, 317 U.S. 1, 28, 31, 63 S.Ct. 2, 87 L.Ed. 3 (1942). There are three traditional bases for military commission jurisdiction: military government, martial law and the law of war. See Hamdan, 548 U.S. at 595-98, 126 S.Ct. 2749 (plurality opinion); see also id. at 683, 126 S.Ct. 2749 (Thomas, J., dissenting). First, military commissions may try ordinary crimes—e.g., manslaughter or robbery—and violations of military orders committed by both soldiers and civilians in territories under U.S. military government. Id. at 595-96, 126 S.Ct. 2749. Second, military commissions may try ordinary crimes and violations of military orders committed by soldiers and civilians in territory under martial law—as much of our country was during the Civil War. See id. at 595, 126 S.Ct. 2749; William Winthrop, Military Law and Precedents 832-34 (rev.2d ed.1920). Third, and “utterly different” from the first two categories, military commissions may try offenses against the law of war. Hamdan, 548 U.S. at 596, 126 S.Ct. 2749 (plurality opinion) (citation omitted). It is undisputed that the commission that tried Bahlul is of the third type: a law-of-war military commission. A military commission convened pursuant to the 2006 MCA must be composed of at least five “members,” who are qualified active duty officers of the armed forces and play a role similar to a petit jury. 10 U.S.C. §§ 948i, 948m. A military judge presides over the trial. Id. § 948j. In 2008, military prosecutors amended the charges against Bahlul to allege three of the offenses enumerated in the 2006 MCA based on the conduct summarized above-conspiracy to commit war crimes, providing material support for terrorism and solicitation of others to commit war crimes. See id. §§ 950u, 950v(b)(25), 950v(b)(28) (2006). The conspiracy and solicitation charges alleged seven object crimes proscribed by the 2006 MCA: murder of protected persons, attacking civilians, attacking civilian objects, murder in violation of the law of war, destruction of property in violation of the law of war, terrorism and providing material support for terrorism. See id. § 950v(b)(l)-(3), (15)—(16), (24)-(25). Bahlul admitted all of the factual allegations against him, with the exception of the allegation that he had armed himself with a suicide belt to protect bin Laden. He nevertheless pleaded not guilty to the charged offenses because he denied the legitimacy of the military commission and sought to absent himself from the proceedings as a boycott. He objected to representation by appointed defense counsel and expressed a desire to proceed pro se, although his attempts to absent himself from the proceedings at times complicated matters and forced defense counsel to stand in for Bahlul and carry out his instructions not to present a defense. Bahlul waived all pretrial motions, asked no questions during voir dire, made no objections to prosecution evidence, presented no defense and declined to make opening and closing arguments. The military commission convicted Bah-lul of all three offenses. Using a detailed findings worksheet, it found that Bahlul conspired to commit and solicited each of the seven alleged object offenses and that Bahlul committed ten of the eleven alleged overt acts. See Petitioner’s Appendix (App.) 132-33. The commission sentenced him to life imprisonment and the convening authority, Susan J. Crawford, approved the findings and sentence. The CMCR affirmed Bahlul’s conviction and sentence in a 112-page opinion. See United States v. Bahlul, 820 F.Supp.2d 1141 (2011). Bahlul then appealed to this Court. While Bahlul’s appeal was pending, this Court held that the 2006 MCA “does not authorize retroactive prosecution for conduct committed before enactment of that Act unless the conduct was already prohibited under existing U.S. law as a war crime triable by military commission.” Hamdan v. United States (Hamdan II), 696 F.3d 1238, 1248 (D.C.Cir.2012) (emphasis in original). The Court declared that providing material support for terrorism—the only charge at issue in that appeal—was not a pre-existing war crime triable by military commission; it therefore vacated Hamdan’s conviction on that offense. Id. at 1248-53. The Government subsequently conceded that Hamdan II’s reasoning required vacatur of all three of Bahlul’s convictions. Based on that concession, a panel of this Court vacated the convictions. Order, Bahlul v. United States, No. 11-1324, 2013 WL 297726 (D.C.Cir. Jan. 25, 2013). We subsequently granted the Government’s petition for rehearing en banc. II. Standard of Review Bahlul argues that the 2006 MCA must be construed to make triable by military commission only those crimes that were recognized under the international law of war when committed. He further contends that, if the 2006 MCA authorizes retroactive prosecution of new law-of-war offenses by military commission, his convictions violate the Ex Post Facto Clause. Bahlul made neither of these arguments before the military commission. “—‘No procedural principle is more familiar to this Court than that a constitutional right,’ or a right of any other sort, ‘may be forfeited in criminal as well as civil cases by the failure to make timely assertion of the right before a tribunal having jurisdiction to determine it.’ ” United States v. Olano, 507 U.S. 725, 731, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993) (quoting Yakus v. United States, 321 U.S. 414, 444, 64 S.Ct. 660, 88 L.Ed. 834 (1944)). This fundamental principle of appellate review generally bars a party who failed to preserve an argument in a lower tribunal from raising it on appeal absent plain error or exceptional circumstances. See United States v. Atkinson, 297 U.S. 157, 159, 56 S.Ct. 391, 80 L.Ed. 555 (1936); Salazar ex rel. Salazar v. Dist. of Columbia, 602 F.3d 431, 437 (D.C.Cir.2010). To preserve error for appellate review, an appellant must interpose a “timely” objection, United States v. Simpson, 430 F.3d 1177, 1183 (D.C.Cir. 2005), and “state the specific ground for [the] objection,” United States v. Boyd, 54 F.3d 868, 872 (D.C.Cir.1995). Although he need not “cite the particular case that supports his position,” United States v. Rashad, 396 F.3d 398, 401 (D.C.Cir.2005), he must state the ground for his objection “with sufficient precision to indicate distinctly [his] thesis,” Miller v. Avirom, 384 F.2d 319, 322 (D.C.Cir.1967). Thus, “[a]n objection is not properly raised if it is couched in terms too general to have alerted the trial court to the substance of the petitioner’s point.” United States v. Breedlove, 204 F.3d 267, 270 (D.C.Cir. 2000); see also Noonan v. Caledonia Gold Min. Co., 121 U.S. 393, 400, 7 S.Ct. 911, 30 L.Ed. 1061 (1887) (“The rule is universal, that where an objection is so general as not to indicate the specific grounds upon which it is made, it is unavailing on appeal, unless it be of such a character that it could not have been obviated at the trial.”). The contemporaneous-objection rule is not mere “obeisance to ritual.” Miller, 384 F.2d at 322. It serves two purposes. First, the rule promotes judicial efficiency by giving the trial tribunal the opportunity to quickly and efficiently resolve errors that would otherwise require burdensome and unnecessary appellate review and remand. See Puckett v. United States, 556 U.S. 129, 134, 129 S.Ct. 1423, 173 L.Ed.2d 266 (2009). Second, the rule discourages the intentional withholding of an objection by a party to be raised on appeal only if he loses at trial. See id.; see also Wainwright v. Sykes, 433 U.S. 72, 89, 97 S.Ct. 2497, 53 L.Ed.2d 594 (1977); Hormel v. Helvering, 312 U.S. 552, 556, 61 S.Ct. 719, 85 L.Ed. 1037 (1941); United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 238-39, 60 S.Ct. 811, 84 L.Ed. 1129 (1940) (citing Crumpton v. United States, 138 U.S. 361, 364, 11 S.Ct. 355, 34 L.Ed. 958 (1891)). To mitigate the sometimes harsh results of the forfeiture rule in criminal cases, the Congress authorizes the court of appeals to exercise its discretion to notice and correct a certain type of forfeited error: “plain error.” Fed.R.CRIm.P. 52(b); see United States v. Young, 470 U.S. 1, 15, 105 S.Ct. 1038, 84 L.Ed.2d 1 (1985); see also 10 U.S.C. § 950a(a) (Supp. Ill 2010) (Military Commissions Act of 2009 review provision specifying that only errors that “materially prejudice[ ] the substantial rights of the accused” may be corrected). A plain error is “[1] an ‘error’ [2] that is ‘plain’ and [3] that ‘affect[s] substantial rights.’ ” Olano, 507 U.S. at 732, 113 S.Ct. 1770 (quoting Fed. R. Ckim P. 52(b)) (final alteration in original). “If all three conditions are met, an appellate court may then exercise its discretion to notice a forfeited error, but only if (4) the error seriously affects the fairness, integrity, or public reputation of judicial proceedings.” Johnson v. United States, 520 U.S. 461, 467, 117 S.Ct. 1544, 137 L.Ed.2d 718 (1997) (quotation marks and brackets omitted). Plain-error review, however, is “highly circumscribed.” United States v. Brinson-Scott, 714 F.3d 616, 625 (D.C.Cir.2013); see also Puckett, 556 U.S. at 134, 129 S.Ct. 1423 (“Meeting all four prongs is difficult, as it should be.” (quotation marks omitted)); Young, 470 U.S. at 15, 105 S.Ct. 1038 (“[T]he plain-error exception to the contemporaneous-objection rule is to be used sparingly, solely in those circumstances in which a miscarriage of justice would otherwise result.” (quotation marks omitted)). “There is good reason for this; anyone familiar with the work of courts understands that errors are a constant in the trial process, that most do not much matter, and that a reflexive inclination by appellate courts to reverse because of unpre-served error would be fatal” to the policies furthered by the contemporaneous-objection rule. Puckett, 556 U.S. at 134, 129 S.Ct. 1423 (quotation marks omitted). We therefore must guard against “unwarranted extension of this exacting definition of plain error.” Young, 470 U.S. at 15, 105 S.Ct. 1038. Applying these principles here, we conclude that Bahlul forfeited the arguments he now raises. He flatly refused to participate in the military commission proceedings and instructed his trial counsel not to present a substantive defense. Although he objected to the commission’s authority to try him, his objection was couched entirely in political and religious terms. He disclaimed guilt and contended that “what [he] did was not a crime.” Trial Tr. 175. But context makes clear that Bahlul argued that his acts were not criminal because they were inspired by religious fervor. See id. at 175-76. After claiming that the United States had “put on the side[ ] the meaningless American laws” and “legislated new laws” for “the planet Earth,” he explained that he “believe[s] that no one has the right in the land to set laws for the people, the right of legislating laws[] is absolutely to Allah, the All Mighty.” Id. at 23-24. Bahlul did ask a “legal question” about whether the “law here by you stems from the action, before action, or post action,” id. at 104, but the military judge could not ascertain what Bahlul was asking and Bahlul did not elaborate. Bahlul’s objection to the commission’s authority was unquestionably “too general to have alerted the trial court to the substance of [his] point.” United States v. Bolla, 346 F.3d 1148, 1152 (D.C.Cir.2003) (Roberts, J.) (quotation marks omitted); Breedlove, 204 F.3d at 270. Accordingly, we review his convictions for plain error. Two of our colleagues contend that, by applying only plain-error review, we have provided insufficient clarity in this case. They argue that the Executive Branch’s need for guidance in this area warrants de novo review. Brown Op. 34, 62; Kava-naugh Op. 80. But the Government itself has asked that we apply plain-error review. E.B. Br. of the United States 63. Indeed, at oral argument, it insisted that we do so, notwithstanding the potential lack of “clarity” that such review might entail. Oral Arg. Tr. 45. III. Statutory Analysis As noted, Hamdan II held that the 2006 MCA “does not authorize retroactive prosecution for conduct committed before enactment of that Act unless the conduct was already prohibited under existing U.S. law as a war crime triable by military commission.” 696 F.3d at 1248. Because we conclude, for the reasons that follow, that the 2006 MCA is unambiguous in its intent to authorize retroactive prosecution for the crimes enumerated in the statute— regardless of their pre-existing law-of-war status—we now overrule Hamdan II’s statutory holding. See United States v. Burwell, 690 F.3d 500, 504 (D.C.Cir.2012) (en banc); Critical Mass Energy Project v. NRC, 975 F.2d 871, 876 (D.C.Cir.1992) (en banc); Save Our Cumberland Mountains, Inc. v. Hodel, 857 F.2d 1516, 1524 (D.C.Cir.1988) (en banc). A. The 2006 MCA is Unambiguous The 2006 MCA confers jurisdiction on military commissions to try “any offense made punishable by this chapter or the law of war when committed by an alien unlawful enemy combatant before, on, or after September 11, 2001.” 10 U.S.C. § 948d(a) (2006) (emphases added). “Any,” in this context, means “all.” See OxfoRD English Dictionary 539 (2d ed.1989) (“indifference as to the particular one or ones that may be selected”); see also Dep’t of Housing & Urban Dev. v. Rucker, 535 U.S. 125, 131, 122 S.Ct. 1230, 152 L.Ed.2d 258 (2002); United States v. Gonzales, 520 U.S. 1, 5, 117 S.Ct. 1032, 137 L.Ed.2d 132 (1997). The “offense[s] made punishable by this chapter” include the charges of which Bahlul was convicted: conspiracy to commit war crimes, providing material support for terrorism and solicitation of others to commit war crimes. 10 U.S.C. §§ 950u, 950v(b)(25), 950v(b)(28) (2006). There could hardly be a clearer statement of the Congress’s intent to confer jurisdiction on military commissions to try the enumerated crimes regardless whether they occurred “before, on, or after September 11, 2001.” And the provisions of the statute enumerating the crimes triable thereunder expressly “do not preclude trial for crimes that occurred before the date of the enactment of this chapter.” 10 U.S.C. § 950p(b) (2006). For good reason: If it were otherwise, section 948d’s conferral of jurisdiction to prosecute the enumerated crimes occurring on or before September 11, 2001 would be inoperative. See Corley v. United States, 556 U.S. 303, 314, 129 S.Ct. 1558, 173 L.Ed.2d 443 (2009) (“A statute should be construed so that effect is given to all its provisions, so that no part will be inoperative or superfluous, void or insignificant.” (quotation marks, brackets and ellipsis omitted)). Although we presume that statutes apply only prospectively “absent clear congressional intent” to the contrary, that presumption is overcome by the clear language of the 2006 MCA. Landgraf v. USI Film Prods., 511 U.S. 244, 280, 114 S.Ct. 1483, 128 L.Ed.2d 229 (1994); see also Johnson v. United States, 529 U.S. 694, 701, 120 S.Ct. 1795, 146 L.Ed.2d 727 (2000) (clear statement of intent overcomes presumption against ret-roactivity); Martin v. Hadix, 527 U.S. 343, 353-54, 119 S.Ct. 1998, 144 L.Ed.2d 347 (1999) (“ ‘unambiguous directive’ or ‘express command’” overcomes presumption against retroactivity); Reynolds v. M’Arthur, 27 U.S. (2 Pet.) 417, 434, 7 L.Ed. 470 (1829) (Marshall, C.J.) (“[L]aws by which human action is to be regulated ... are never to be construed retrospectively unless the language of the act shall render such construction indispensable.”). Review of the inter-branch dialogue which brought about the 2006 MCA confirms the Congress’s intent to apply all of the statute’s enumerated crimes retroactively. See Boumediene v. Bush, 553 U.S. 723, 738, 128 S.Ct. 2229, 171 L.Ed.2d 41 (2008) (“acknowledging] ... the litigation history that prompted Congress to enact the MCA”). In Hamdan v. Rumsfeld, 548 U.S. 557, 126 S.Ct. 2749, 165 L.Ed.2d 723 (2006), the Supreme Court considered the President’s order that a military commission try Hamdan, a Guantanamo detainee, for one of the very crimes of which Bahlul was convicted: conspiracy to commit war crimes. Hamdan challenged the President’s authority to convene the military commission by petitioning for habeas corpus relief and the Supreme Court’s resulting decision initiated two games of interpretive ping-pong between the judiciary and the legislature. One involves the issue presented here: whether conspiracy is triable by a law-of-war military commission. In Hamdan, four justices concluded that it was not triable under the extant statute (section 821) and three concluded that it was. Compare Hamdan, 548 U.S. at 603-13, 126 S.Ct. 2749 (plurality opinion of Stevens, J.), with id. at 697-704, 126 S.Ct. 2749 (Thomas, J., dissenting). Four justices also “specifically invited Congress to clarify the scope of the President’s statutory authority to use military commissions to try unlawful alien enemy combatants for war crimes.” Hamdan II, 696 F.3d at 1243; see Hamdan, 548 U.S. at 636, 126 S.Ct. 2749 (Breyer, J., concurring) (“Nothing prevents the President from returning to Congress to seek the authority he believes necessary.”); id. at 637, 126 S.Ct. 2749 (Kennedy, J., concurring) (“If Congress, after due consideration, deems it appropriate to change the controlling statutes, in conformance with the Constitution and other laws, it has the power and prerogative to do so.”). The Congress answered the Court’s invitation with the 2006 MCA, which provides the President the very power he sought to exercise in Hamdan—the power to try the 9/11 perpetrators for conspiracy—by including conspiracy as an offense triable by military commission, 10 U.S.C. § 950v(b)(28) (2006), and by conferring jurisdiction on military commissions to try alien unlawful enemy combatants for conspiracy based on conduct that occurred “before, on, or after September 11, 2001,” id. § 948d(a). We must heed this inter-branch dialogue, as Boumediene instructs. 553 U.S. at 738,128 S.Ct. 2229. If this sounds familiar, it does so because it mirrors a second game of interpretive ping-pong begun in Hamdan. There, the Court also addressed the Government’s contention that section 1005(e)(1) of the Detainee Treatment Act of 2005(DTA), Pub.L. 109-148, 119 Stat. 2739, 2741-42—enacted after the Court’s grant of certiorari in Hamdan—ousted it of jurisdiction to entertain Hamdan’s habe-as petition. Hamdan, 548 U.S. at 572, 126 S.Ct. 2749. After a lengthy statutory analysis, the Court construed the DTA to apply only to petitions filed after the DTA’s enactment and, because Hamdan’s petition was filed before, the statute did not apply. Id. at 576-84, 126 S.Ct. 2749. In construing the DTA as it did, the Court avoided addressing “grave questions about Congress’ authority to impinge upon this Court’s appellate jurisdiction, particularly in habeas cases” and whether the Congress had unconstitutionally suspended the writ of habeas corpus. Id. at 575, 126 S.Ct. 2749. Although the Court relied on “[ojrdinary principles of statutory construction” to reach its result, id., its practical message to the Congress was clear: Stripping the courts of jurisdiction over detainees’ pending habeas petitions must be done unambiguously. Three justices dissented, arguing that the DTA was already unambiguous in its intent to repeal the Court’s jurisdiction. Id. at 656-69,126 S.Ct. 2749 (Scalia, J., dissenting). The Congress returned serve in the 2006 MCA. Section 7(b) clarified that the bar to habeas jurisdiction applied to “all cases, without exception, pending on or after the date” of the statute’s enactment. 2006 MCA, § 7(b), 120 Stat. at 2636. Two years later, a detainee whose habeas petition was pending at the time of the 2006 MCA’s enactment argued that the statute did not apply to his case because section 7(b) was not a “sufficiently clear statement of congressional intent to strip the federal courts of jurisdiction in pending cases.” Boumediene, 553 U.S. at 737, 128 S.Ct. 2229. This time, the Court rejected the argument. It explained: If the Court invokes a clear statement rule to advise that certain statutory interpretations are favored in order to avoid constitutional difficulties, Congress can make an informed legislative choice either to amend the statute or to retain its existing text. If Congress amends, its intent must be respected even if a difficult constitutional question is presented. The usual presumption is that Members of Congress, in accord with their oath of office, considered the constitutional issue and determined the amended statute to be a lawful one; and the Judiciary, in light of that determination, proceeds to its own independent judgment on the constitutional question when required to do so in a proper case. If this ongoing dialogue between and among the branches of Government is to be respected, we cannot ignore that the MCA was a direct response to Hamdan’s holding that the DTA’s jurisdiction-stripping provision had no application to pending cases. Id. at 738, 128 S.Ct. 2229 (emphases added). Having avoided the Suspension Clause issue in Hamdan by virtue of its construction of the statute and having been answered by the Congress’s reenactment of its retroactive intent, the Court had no choice but to resolve the difficult constitutional question presented (whether the MCA violated the Suspension Clause). The same thing happened here. In enacting the military commission provisions of the 2006 MCA, the Congress plainly intended to give the President the power which Hamdan held it had not previously supplied—just as the 2006 MCA clarified that in fact the Congress did intend section 7(b)’s ouster of habeas jurisdiction to apply to pending cases. The legislative history confirms this view. See Bourne-diene, 553 U.S. at 739, 128 S.Ct. 2229 (“The Court of Appeals was correct to take note of the legislative history when construing the statute.... ”). Supporters and opponents of the legislation alike agreed that the 2006 MCA’s purpose was to authorize the trial by military commission of the 9/11 conspirators. And because the 9/11 conspiracy took place long before 2006, the statute could accomplish its explicit purpose only if it applied to pre-enactment conduct. As the Court itself made clear, “we cannot ignore that the [2006] MCA was a direct response to Hamdan ’s holding.” Boumediene, 553 U.S. at 739, 128 S.Ct. 2229. Reading the MCA in this context and given the unequivocal nature of its jurisdictional grant, we conclude the 2006 MCA unambiguously authorizes Bahlul’s prosecution for the charged offenses based on pre-2006 conduct. B. The Avoidance Canon is Inapplicable Hamdan II’s contrary conclusion turned on the following provision of the 2006 MCA: (a) PüRpose.—The provisions of this subchapter codify offenses that have traditionally been triable by military commissions. This chapter does not establish new crimes that did not exist before its enactment, but rather codifies those crimes for trial by military commission. (b) EpfeCt.—Because the provisions of this subchapter (including provisions that incorporate definitions in other provisions of law) are declarative of existing law, they do not preclude trial for crimes that occurred before the date of the enactment of this chapter. 10 U.S.C. § 950p (2006). In Hamdan II, the Court read this provision to reflect the Congress’s “belie[f| that the Act codified no new crimes and thus posed no ex post facto problem.” 696 F.3d at 1247. Because the Congress was wrong in its textually stated premise—ie., the Act did codify new war crimes—the Court found “at least something of an ambiguity” in the statute. Id. at 1248. It then turned to the avoidance canon to resolve the ambiguity, concluding that the Congress intended to authorize retroactive prosecution only if “the conduct was already prohibited under existing U.S. law as a war crime triable by military commission.” Id. The “avoidance canon” reflects a fundamental principle of judicial restraint. See Ashwander v. TVA 297 U.S. 288, 341-48, 56 S.Ct. 466, 80 L.Ed. 688 (1936) (Brandéis, J., concurring). But “[t]he canon of constitutional avoidance comes into play only when, after the application of ordinary textual analysis, the statute is found to be susceptible of more than one construction; and the canon functions as a means of choosing between them.” Clark v. Martinez, 543 U.S. 371, 385, 125 S.Ct. 716, 160 L.Ed.2d 734 (2005) (emphasis in original); see also Milavetz, Gallop & Milavetz, P.A. v. United States, 559 U.S. 229, 239, 130 S.Ct. 1324, 176 L.Ed.2d 79 (2010). If, after applying ordinary principles of textual analysis, the statute is not genuinely open to two constructions, the “canon of constitutional avoidance does not apply.” Gonzales v. Carhart, 550 U.S. 124, 154, 127 S.Ct. 1610, 167 L.Ed.2d 480 (2007). Because the 2006 MCA unqualifiedly confers jurisdiction on military commissions to try “any offense made punishable by this chapter or the law of war when committed by an alien unlawful enemy combatant before, on, or after September 11, 2001,” 10 U.S.C. § 948d(a) (2006) (emphases added), it is not “fairly possible” to read the statute to apply only prospectively. United States v. Jin Fuey Moy, 241 U.S. 394, 401, 36 S.Ct. 658, 60 L.Ed. 1061 (1916) (Holmes, J.). Hamdan II perceived a “tight causal link between (i) Congress’s belief that the statute codified only crimes under pre-existing law and (ii) Congress’s statement that the new statute could therefore apply to conduct before enactment.” 696 F.3d at 1247-48. We think that link plainly affirms the Congress’s intent to apply the statute retroactively. “The Congress is a coequal branch of government whose Members take the same oath we do to uphold the Constitution of the United States.” Rostker v. Goldberg, 453 U.S. 57, 64, 101 S.Ct. 2646, 69 L.Ed.2d 478 (1981). We assume that, in meeting that oath, it “legislates in the light of constitutional limitations.” Rust v. Sullivan, 500 U.S. 173, 191, 111 S.Ct. 1759, 114 L.Ed.2d 233 (1991); see also Edward J. DeBartolo Corp. v. Fla. Gulf Coast Bldg. & Constr. Trades Council, 485 U.S. 568, 575, 108 S.Ct. 1392, 99 L.Ed.2d 645 (1988); FTC v. Am. Tobacco Co., 264 U.S. 298, 305-06, 44 S.Ct. 336, 68 L.Ed. 696 (1924); United States v. Harris, 106 U.S. 629, 635, 1 S.Ct. 601, 27 L.Ed. 290 (1883); Joint Anti-Fascist Refugee Comm. v. McGrath, 341 U.S. 123, 164, 71 S.Ct. 624, 95 L.Ed. 817 (1951) (Frankfurter, J., concurring). As section 950p makes abundantly clear, the Congress made precisely that assessment and, whether right or wrong, concluded that the statute fell within the constitutional limits of its legislative authority. See City of Boerne v. Flores, 521 U.S. 507, 535, 117 S.Ct. 2157, 138 L.Ed.2d 624 (1997) (“When Congress acts within its sphere of power and responsibilities, it has not just the right but the duty to make its own informed judgment on the meaning and force of the Constitution.”); United States v. Nixon, 418 U.S. 683, 703, 94 S.Ct. 3090, 41 L.Ed.2d 1039 (1974) (“In the performance of assigned constitutional duties each branch of the Government must initially interpret the Constitution, and the interpretation of its powers by any branch is due great respect from the others.”). Indeed, the legislative history reveals the breadth of the Congress’s debate on the statute’s constitutionality. See, e.g., H.R.Rep. No. 109-664, at 25 (“For the reasons stated in Justice Thomas’s opinion [in Hamdan ], the Committee [on Armed Services] views conspiracy as a separate offense punishable by military commissions.”). The “ambiguity” Hamdan II identified was the Congress’s failure to address what it “would ... have wanted” if it “had known that the Act was codifying some new crimes.” 696 F.3d at 1247. In other words, Hamdan II found the statute ambiguous because the Congress did not include in the text of the statute alternative language in case it was wrong in its reading of the law on which it premised its legislation. But the Congress always legislates on the basis of some set of facts or premises it believes to be true. It holds hearings and investigates precisely for the purpose of acquiring facts and then legislates on the basis of those facts. Because it believes to be true the facts on which it bases its legislation, the Congress seldom (if ever) includes instructions on what to do if those facts are proven incorrect. Here, the Congress authorized prosecution for “any offense made punishable by” the 2006 MCA, including offenses based on pre-enactment conduct, precisely because it believed that all of the offenses were already triable by military commission. The Congress’s plainly expressed belief about pre-enactment law should govern our understanding of the Congress’s intent expressed in the text of the statute. If judicial inquiry reveals that the Congress was mistaken, it is not our task to rewrite the statute to conform with the actual state of the law but rather to strike it down insofar as the Congress’s mistake renders the statute unconstitutional. See Ass’n of Am. Railroads v. U.S. Dep’t of Transp., 721 F.3d 666, 673 n. 7 (D.C.Cir. 2013) (“The constitutional avoidance canon is an interpretive aid, not an invitation to rewrite statutes to satisfy constitutional strictures.”), cert. granted (June 23, 2014). Moreover, the avoidance canon ordinarily requires no speculation into the Congress’s hypothetical intent: If the statute’s text is ambiguous, we choose a constitutional construction over an unconstitutional one. Here, however, the “ambiguity” lies not in the text itself but in the text when read in light of Hamdan II’s subsequent finding that the premise on which the text is based is wrong. That is, the “ambiguity” lies in the existence of matters unknown to the Congress. But “[w]e cannot replace the actual text with speculation as to Congress’ intent,” Magwood, v. Patterson, 561 U.S. 320, 130 S.Ct. 2788, 2798, 177 L.Ed.2d 592 (2010), nor can we “divin[e] what Congress would have wanted if it had thought of the situation before the court,” Morrison v. Nat’l Australia Bank Ltd., 561 U.S. 247, 130 S.Ct. 2869, 2881, 177 L.Ed.2d 535 (2010); see also United States v. Public Utilities Comm’n of Cal., 345 U.S. 295, 319, 73 S.Ct. 706, 97 L.Ed. 1020 (1953) (Jackson, J., concurring) (“Never having been a Congressman, I am handicapped in that weird endeavor. That process seems to me not interpretation of a statute but creation of a statute.”). For that reason, “our inquiry focuses on an analysis of the textual product of Congress’ efforts, not on speculation as to the internal thought processes of its Members.” Carter v. United States, 530 U.S. 255, 272, 120 S.Ct. 2159, 147 L.Ed.2d 203 (2000); see also Gardner v. Collins, 27 U.S. (2 Pet.) 58, 93, 7 L.Ed. 347 (1829) (“What the legislative intention was, can be derived only from the words they have used; and we cannot speculate beyond the reasonable import of these words.”). Even if it may raise difficult constitutional questions, the statutory text remains the gravamen of our interpretive inquiry. See United States v. Raynor, 302 U.S. 540, 552, 58 S.Ct. 353, 82 L.Ed. 413 (1938). “Although [we] will often strain to construe legislation so as to save it against constitutional attack,” Aptheker v. Sec’y of State, 378 U.S. 500, 515, 84 S.Ct. 1659, 12 L.Ed.2d 992 (1964) (quotation marks omitted), a court cannot “rewrite a law to conform it to constitutional requirements, for doing so would constitute a serious invasion of the legislative domain,” United States v. Stevens, 559 U.S. 460, 481, 130 S.Ct. 1577, 176 L.Ed.2d 435 (2010) (quotation marks, ellipsis and citations omitted). “Here the intention of the Congress is revealed too distinctly to permit us to ignore it because of mere misgivings as to power. The problem must be faced and answered.” George Moore Ice Cream Co. v. Rose, 289 U.S. 373, 379, 53 S.Ct. 620, 77 L.Ed. 1265 (1933) (Cardozo, J.). IV. Bahlul’s Ex Post Facto Challenge Because the Congress’s intent to authorize retroactive prosecution of the charged offenses is clear, we must address Bahlul’s ex post facto argument. See Cohens v. Virginia, 19 U.S. (6 Wheat.) 264, 404, 5 L.Ed. 257 (1821) (Marshall, C.J.) (“Questions may occur which we would gladly avoid; but we cannot avoid them. All we can do is, to exercise our best judgment, and conscientiously to perform our duty.”). As noted, we may overturn Bahlul’s convictions only if they constitute plain constitutional error. The Constitution prohibits the Congress from enacting any “ex post facto Law.” U.S. Const, art. I, § 9, cl. 3. “The phrase ex post facto law was a term of art with an established meaning at the time of the framing.” Peugh v. United States, — U.S. -, 133 S.Ct. 2072, 2081, 186 L.Ed.2d 84 (2013) (quoting Collins v. Youngblood, 497 U.S. 37, 41, 110 S.Ct. 2715, 111 L.Ed.2d 30 (1990)) (quotation marks omitted). In Calder v. Bull, Justice Chase set forth his understanding of that meaning: 1st. Every law that makes an action, done before the passing of the law, and which was innocent when done, criminal; and punishes such action. 2nd. Every law that aggravates a crime, or makes it greater than it was, when committed. 3rd. Every law that changes the punishment, and inflicts a greater punishment, than the law annexed to the crime, when committed. 4th. Every law that alters the legal rules of evidence, and receives less, or different, testimony, than the law required at the time of the commission of the offence, in order to convict the offender. 3 U.S. (3 Dall.) 386, 390,1 L.Ed. 648 (1798) (opinion of Chase, J.); see Peugh, 133 S.Ct. at 2081 (reciting Justice Chase’s formulation); Carmell v. Texas, 529 U.S. 513, 525, 120 S.Ct. 1620, 146 L.Ed.2d 577 (2000) (Supreme Court has “repeatedly endorsed” Justice Chase’s formulation); see also id. at 537-39, 120 S.Ct. 1620 (noting that Collins did not eliminate Justice Chase’s fourth category). In our order granting en banc review, we asked the parties to brief whether the Ex Post Facto Clause applies in cases involving aliens detained at Guantanamo. The Government has taken the position that it does. Although we are not obligated to accept the Government’s concession, see Young v. United States, 315 U.S. 257, 258-59, 62 S.Ct. 510, 86 L.Ed. 832 (1942); United States v. Baldwin, 563 F.3d 490, 491 (D.C.Cir.2009), we will assume without deciding that the Ex Post Facto Clause applies at Guantanamo. In so doing, we are “not to be understood as remotely intimating in any degree an opinion on the question.” Petite v. United States, 361 U.S. 529, 531, 80 S.Ct. 450, 4 L.Ed.2d 490 (1960) (per curiam); see also Casey v. United States, 343 U.S. 808, 808, 72 S.Ct. 999, 96 L.Ed. 1317 (1952) (per curiam) (“To accept in this case [the Solicitor General’s] confession of error would not involve the establishment of any precedent.”); United States v. Bell, 991 F.2d 1445, 1447-48 (8th Cir.1993). A. Conspiracy We reject Bahlul’s ex post facto challenge to his conspiracy conviction for two independent and alternative reasons. First, the conduct for which he was convicted was already criminalized under 18 U.S.C. § 2332(b) (section 2332(b)) when Bahlul engaged in it. It is not “plain” that it violates the Ex Post Facto Clause to try a pre-existing federal criminal offense in a military commission and any difference between the elements of that offense and the conspiracy charge in the 2006 MCA does not seriously affect the fairness, integrity or public reputation of judicial proceedings. Second, it is not “plain” that conspiracy was not already triable by law-of-war military commission under 10 U.S.C. § 821 when Bahlul’s conduct occurred. 1. Section 2332(b) Bahlul was convicted of conspiracy to commit seven war crimes enumerated in the 2006 MCA, including the murder of protected persons. Although the 2006 MCA post-dates Bahlul’s conduct, section 2832(b) has long been on the books, making it a crime to, “outside the United States,” “engage[ ] in a conspiracy to kill[ ] a national of the United States.” 18 U.S.C. § 2332(b); see Omnibus Diplomatic Security and Antiterrorism Act of 1986, Pub.L. No. 99-399, § 1202(a), 100 Stat. 853, 896. Section 2332(b) is not an offense triable by military commission but, the Government argues, “[t]he fact that the MCA provides a different forum for adjudicating such conduct does not implicate ex post facto concerns.” E.B. Br. of United States 67. We agree. See infra p. 31 (remanding to panel to determine Bahlul’s other constitutional challenges). The right to be tried in a particular forum is not the sort of right the Ex Post Facto Clause protects. See Collins, 497 U.S. at 51, 110 S.Ct. 2715. In Collins, the Supreme Court sifted through its Ex Post Facto Clause precedent, noting that some cases had said that a “procedural” change—ie., a “change[] in the procedures by which a criminal case is adjudicated”—may violate the Ex Post Facto Clause if the change “affects matters of substance” by “depriving a defendant of substantial protections with which the existing law surrounds the person accused of crime or arbitrarily infringing upon substantial personal rights.” Id. at 45, 110 S.Ct. 2715 (citations, brackets and quotation marks omitted). The Court observed that such language had “imported confusion” into its doctrine and it attempted to reconcile that language so as to not enlarge the Ex Post Facto Clause’s application beyond laws that “make innocent acts criminal, alter the nature of the offense, or increase the punishment.” Id. at 46, 110 S.Ct. 2715. One case that could not be reconciled was Thompson v. Utah, in which the Court had found that a change in Utah law reducing the size of criminal juries from 12 to 8 persons violated the Ex Post Facto Clause by depriving the defendant of “a substantial right involved in his liberty.” 170 U.S. 343, 352-53, 18 S.Ct. 620, 42 L.Ed. 1061 (1898). The Court overruled Thompson in Collins, explaining that the reduced size of the jury was not in fact an ex post facto violation because “[t]he right to jury trial provided by the Sixth Amendment is obviously a ‘substantial’ one, but it is not a right that has anything to do with the definition of crimes, defenses, or punishments, which is the concern of the Ex Post Facto Clause.” Collins, 497 U.S. at 51, 110 S.Ct. 2715. Similarly, in Cook v. United States, the Court held that an act vesting jurisdiction over a crime in a newly formed judicial district does not violate the Ex Post Facto Clause because “[i]t only ... subjects the accused to trial in th[e new] district rather than in the court of some other judicial district established by the government against whose laws the offense was committed. This does not alter the situation of the defendants in respect to their offense or its consequences.” 138 U.S. 157, 183, 11 S.Ct. 268, 34 L.Ed. 906 (1891); accord Gut v. Minnesota, 76 U.S. 35, 38, 9 Wall. 35, 19 L.Ed. 573 (1869) (“An ex post facto law does not involve, in any of its definitions, a change of the place of trial of an alleged offence after its commission.”); see also Duncan v. Missouri, 152 U.S. 377, 382-83, 14 S.Ct. 570, 38 L.Ed. 485 (1894) (suggesting no ex post facto violation where defendant’s appeal was heard by smaller appellate panel than provided for at time of his offense). It is therefore not a plain ex post facto violation to transfer jurisdiction over a crime from an Article III court to a military commission because such a transfer does not have anything to do with the definition of the crime, the defenses or the punishment. That is so regardless of the different evidentiary rules that apply under the 2006 MCA. See Carmell, 529 U.S. at 533 n. 23, 120 S.Ct. 1620 (change in “[o]rdinary rules of evidence ... do[es] not violate the [Ex Post Facto] Clause”); id. at 542-47, 120 S.Ct. 1620; Collins, 497 U.S. at 43 n. 3, 110 S.Ct. 2715; Beazell v. Ohio, 269 U.S. 167, 171, 46 S.Ct. 68, 70 L.Ed. 216 (1925); Thompson v. Missouri, 171 U.S. 380, 386-88, 18 S.Ct. 922, 43 L.Ed. 204 (1898); Hopt v. Utah, 110 U.S. 574, 589-90, 4 S.Ct. 202, 28 L.Ed. 262 (1884). Nor is this a case like Carmell, where a law retroactively reduced the “quantum of evidence necessary to sustain a conviction,” 529 U.S. at 530, 120 S.Ct. 1620; the 2006 MCA requires the Government to prove guilt beyond a reasonable doubt, see 10 U.S.C. § 949Z(c); see also Trial Tr. 233, 878 (military judge’s instructions to commission). Our inquiry is not ended, however, because the 2006 MCA conspiracy-to-murder-protected-persons charge and section 2332(b) do not have identical elements. The difference is a potential problem because the Ex Post Facto Clause prohibits “retrospectively eliminating an element of the offense” and thus “subverting] the presumption of innocence by reducing the number of elements [the government] must prove to overcome that presumption.” Carmell, 529 U.S. at 532, 120 S.Ct. 1620. Both statutes require the existence of a conspiracy and an overt act in furtherance thereof. See 18 U.S.C. § 2332(b)(2); 10 U.S.C. § 950v(b)(28) (2006); see also Trial Tr. 846, 849-50 (military judge’s instructions to commission). The 2006 MCA conspiracy charge is in one sense more difficult to prove than section 2332(b) because it applies only to alien unlawful enemy combatants engaged in hostilities against the United States. See 10 U.S.C. §§ 948b(a), 948c, 948d; see also Trial Tr. 843-45 (instructions). But the 2006 MCA charge is in two ways easier to prove than a section 2332(b) charge. It does not require that the conspiracy occur “outside the United States” or that the conspiracy be to kill a “national of the United States,” as section 2332(b) does. It simply requires a conspiracy to murder “one or more protected persons.” Trial Tr. 850-51 (instructions); see supra n. 10 (providing MCA’s definition of “protected person”). Although the two statutes are quite similar, then, the 2006 MCA conspiracy charge eliminates two elements required to convict a defendant under section 2332(b). Nevertheless, Bahlul cannot bear his burden of establishing that the elimination of the two elements “seriously affect[ed] the fairness, integrity or public reputation of judicial proceedings.” Olano, 507 U.S. at 732, 113 S.Ct. 1770 (quotation marks omitted); see United States v. Vonn, 535 U.S. 55, 62-63, 122 S.Ct. 1043, 152 L.Ed.2d 90 (2002) (defendant bears burden of proving Olano’s fourth prong); see also United States v. Johnson, 331 F.3d 962, 967 (D.C.Cir .2003) (proceeding directly to fourth prong if it can resolve appeal). He cannot satisfy the fourth prong because the charges against him and the commission’s findings necessarily included those elements and the evidence supporting them was undisputed. To explain why requires that we first discuss the most on-point Supreme Court precedent. In Johnson v. United States, the Supreme Court reviewed a defendant’s conviction for perjury where the district court had decided the issue of materiality itself rather than submit that issue to the jury, as the Court’s precedent requires. 520 U.S. 461, 463, 117 S.Ct. 1544, 137 L.Ed.2d 718 (1997). The defendant did not object, however, so the Court reviewed his conviction for plain error. Because the evidence of the missing materiality element was “overwhelming” and “essentially uncontro-verted at trial,” the Court concluded that the error, although plain, did not seriously affect the fairness, integrity or public reputation of judicial proceedings. Id. at 470, 117 S.Ct. 1544; cf. Neder v. United States, 527 U.S. 1, 19, 119 S.Ct. 1827, 144 L.Ed.2d 35 (1999) (failure to submit element to jury was harmless error “where [the] defendant did not, and apparently could not, bring forth facts contesting the omitted element”). Similarly, in United States v. Cotton, the indictment failed to charge the drug quantity involved in the offense, as the Court’s precedent requires for any fact that enhances the otherwise applicable statutory maximum sentence. 535 U.S. 625, 627-28, 122 S.Ct. 1781, 152 L.Ed.2d 860 (2002). After the jury found the defendants guilty of a narcotics conspiracy, the district court made drug quantity findings that enhanced the defendants’ statutory máximums. Id. at 628, 122 S.Ct. 1781. This was “error” and it was “plain” but the Court nevertheless upheld the convictions under Olano’s fourth prong. Because the evidence of the requisite drug quantity was “overwhelming” and “essentially uncontroverted,” the Court concluded that “[t]he real threat ... to the fairness, integrity, and public reputation of judicial proceedings would be if [the defendants] ... were to receive a sentence prescribed for those committing less substantial drug offenses because of an error that was never objected to at trial.” Id. at 633-34, 122 S.Ct. 1781 (quotation marks omitted); accord Johnson, 331 F.3d at 966-70; United States v. Webb, 255 F.3d 890, 899-902 (D.C.Cir.2001). Here, the evidence of the two missing elements was not simply “overwhelming” and “essentially uncontroverted”—it was entirely uncontroverted. Bahlul was charged with committing numerous overt acts “in Afghanistan, Pakistan and elsewhere” that furthered the conspiracy’s unlawful objects; those objects included the murder of protected persons. App. 122-25. He did not dispute that his conduct occurred outside the United States nor did he dispute that the purpose of the conspiracy was to murder United States nationals. See Trial Tr. 167 (Bahlul: “And what I did ... is to kill Americans....”); id. at 511— 12 (“[Bahlul] does not consider anybody protected personfs] or civilians.... [A]s long as you’re a[n] American, you are a target.”). Indeed, several witnesses testified that Bahlul considered all Americans to be targets. Id. at 503, 512, 596, 653. The commission was instructed on the overt acts allegedly undertaken by Bahlul in furtherance of the conspiracy, see id. at 846-47, and was instructed that one of the conspiracy’s object offenses was the murder of protected persons, id. at 850. The commission specifically found that Bahlul committed ten overt acts, all of which took place outside the United States and several of which directly relate to the 9/11 attacks that killed thousands of United States nationals. App. 132-33. And it found that all seven of the alleged object offenses, including murder of protected persons, were objects of the conspiracy. App. 131. There is no scenario in which the commission could have found that Bah-lul committed these overt acts yet rationally found that the conspiracy did not take place outside the United States and did not have as an object the murder of United States nationals. Accord Webb, 255 F.3d at 901. Although the commission was not specifically instructed that it had to find these two elements, the overt acts it did find Bahlul had committed necessarily included the two elements and Bahlul did not, and does not, dispute either. Therefore, although the 2006 MCA conspiracy offense, as charged here, does “eliminatfe] an element of the offense,” Carmell, 529 U.S. at 532, 120 S.Ct. 1620, the omission did not seriously affect the fairness, integrity, or public reputation of the proceedings. 2. Section 821 When Bahlul committed the crimes of which he was convicted, section 821 granted—and still grants—military commissions jurisdiction “with respect to offenders or offenses that by statute or by the law of war may be tried by military commissions.” 10 U.S.C. § 821. Section 821 and its predecessor statute have been on the books for nearly a century. See Pub.L. No. 64-242, 39 Stat. 619, 653 (1916); Pub.L. No. 66-242, 41 Stat. 759, 790 (1920); Pub.L. No. 81-506, 64 Stat. 107, 115 (1950); Madsen v. Kinsella, 343 U.S. 341, 350-51 & n. 17, 72 S.Ct. 699, 96 L.Ed. 988 (1952). We must therefore ascertain whether conspiracy to commit war crimes was a “law of war” offense triable by military commission under section 821 when Bahlul’s conduct occurred because, if so, Bahlul’s ex post facto argument fails. In answering this question, we do not write on a clean slate. In Hamdan, seven justices of the Supreme Court debated the question at length. Four justices concluded that conspiracy is not triable by military commission under section 821. 548 U.S. at 603-13, 126 S.Ct. 2749 (plurality opinion of Stevens, J.). Three justices opined that it is. Id. at 697-704, 126 S.Ct. 2749 (Thomas, J., dissenting). Both opinions scoured relevant international and domestic authorities but neither position garnered a majority. The case was resolved on other grounds and the eighth vote—one justice was recused—left the conspiracy question for another day, noting that the Congress may “provide further guidance in this area.” See id. at 655, 126 S.Ct. 2749 (Kennedy, J., concurring). In light of the uncertainty left by the split, it was not “plain” error to try Bahlul for conspiracy by military commission pursuant to section 821. See United States v. Terrell, 696 F.3d 1257, 1260 (D.C.Cir.2012) (plain error met only if “its erroneous character” is established by “a clear precedent in the Supreme Court or this circuit”). The reason for the uncertainty is not only the divided result in Hamdan but also the High Court’s failure to clearly resolve a subsidiary question: What body of law is encompassed by section 821’s reference to the “law of war”? That dispute takes center stage here. Bahlul contends that “law of war” means the international law of war, full stop. The Government contends that we must look not only to international precedent but also “the common law of war developed in U.S. military tribunals.” E.B. Br. of United States 28; see also Oral Arg. Tr. 15 (“[W]e believe the law of war is the international law of war as supplemented by the experience and practice of our wars and our wartime tribunals.”). The answer is critical because the Government asserts that conspiracy is not an international law-of-war offense. See E.B. Br. of United States 34; Oral Arg. Tr. 15. In Hamdan II, the Court said that “law of war” as used in section 821 is a term of art that refers to the international law of war. 696 F.3d at 1248; see also id. at 1252 (noting that “U.S. precedents may inform the content of international law”); cf. Kavanaugh Op. 68 n. 5 (stating that Hamdan II’s interpretation of section 821 “was not necessary to the result”). Language in several Supreme Court opinions supports that proposition. See, e.g., Quirin, 317 U.S. at 27-28, 63 S.Ct. 2 (“[T]his Court has recognized and applied the law of war as including that part of the law of nations which prescribes, for the conduct of war, the status, rights and duties of enemy nations as well as of enemy individuals.”); id. at 29, 63 S.Ct. 2 (describing law of war as “branch of international law”); see also Hamdan, 548 U.S. at 603, 126 S.Ct. 2749 (plurality) (citing Quirin and describing offense alleged therein as being “recognized as an offense against the law of war” both “in this country and internationally”); id. at 610-11, 126 S.Ct. 2749 (analyzing international law sources); id. at 641, 126 S.Ct. 2749 (Kennedy, J., concurring) (“[T]he law of war ... is the body of international law governing armed conflict.” (citing Quiñn, 317 U.S. at 28, 63 S.Ct. 1)); Madsen, 343 U.S. at 354-55, 72 S.Ct. 699 (“The ‘law of war’ ... includes at least that part of the law of nations which defines the powers and duties of belligerent powers occupying enemy territory pending the establishment of civil government.”); Yamashita, 327 U.S. at 12-16, 66 S.Ct. 340 (analyzing international precedent in determining whether offense was violation of law of war); Rogers Op. 37-38 (concluding on de novo review that section 821 refers to international law of war). Several Executive Branch interpretations and scholarly articles also support that reading. See Hamdan II, 696 F.3d at 1248-49 & n. 9 (collecting citations). On the other hand, section 821 might not be so limited (as two of our colleagues would hold on de novo review). See Brown Op. 52; Kavanaugh Op. 65-68; see also Hamdan, 548 U.S. at 689, 126 S.Ct. 2749 (Thomas, J., dissenting) (“[W]hether an offense is a violation of the law of war cognizable before a military commission must be determined pursuant to the system of common law applied by military tribunals ... [which] is derived from the experience of our wars and our wartime tribunals and the laws and usages of war as understood and practiced by the civilized nations of the world.” (citations and quotation marks omitted)). Significantly, both the Hamdan plurality and dissent relied primarily on domestic precedent to ascertain whether conspiracy could be tried under section 821. See Hamdan, 548 U.S. at 603-09, 126 S.Ct. 2749 (plurality); id. at 689-704, 126 S.Ct. 2749 (Thomas, J., dissenting). There is also language in Yamashita and Quiñn that domestic precedent is an important part of our inquiry. See Yamashita, 327 U.S. at 8, 66 S.Ct. 340 (“[The Congress] adopted the system of military common law applied by military tribunals so far as it should be recognized and deemed applicable by the courts, and as further defined and supplemented by the Hague Convention.... ”); Quirin, 317 U.S. at 31-35, 42 n. 14, 63 S.Ct. 2 (evaluating domestic precedent to determine whether offense charged was law-of-war offense); see also Madsen, 343 U.S. at 347-48, 72 S.Ct. 699. Moreover, as the Supreme Court has explained, when the Congress enacted section 821 and its predecessors, it intended to preserve, not limit, the pre-existing jurisdiction of military commissions. See Madsen, 343 U.S. at 352-53, 72 S.Ct. 699; Yamashita, 327 U.S. at 19-20, 66 S.Ct. 340; see also Hamdan, 548 U.S. at 593, 126 S.Ct. 2749 (majority) (“[T]he Quirin Court recognized that Congress had simply preserved what power, under the Constitution and the common law of war, the President had had before 1916 to convene military commissions-with the express condition that the President and those under his command comply with the law of war.”). It is therefore arguable that the Congress also intended to incorporate military commission precedents predating section 821’s enactment. See Sek-har v. United States, — U.S. -, 133 S.C