concurring.
I agree that increases in risk can be “injuries in fact” sufficient to confer Article III standing, and I concur in the judgment that the risk demonstrated by petitioners in this case is sufficient to support standing.
I also agree that, on the merits, petitioners’ claim fails. As the majority opinion notes, NRDC’s principal argument is that “EPA’s 2005 critical-use rule violates the express terms of the Montreal Protocol Parties’ unanimous Decisions,” Final Opening Br. for Pet’r at 20, and therefore is “not in accordance with law,” 42 U.S.C. § 7607(d)(9)(A). In rejecting this claim, our holding is precise and limited:
The “decisions” of the Parties — post-ratification side agreements reached by consensus among 189 nations — are not “law” within the meaning of the Clean Air Act and are not enforceable in federal court.
Maj. Op. at 8.
On the record before us, this holding is eminently correct for two reasons. First, “[njowhere does the Protocol suggest that the Parties’ post-ratification consensus agreements about how to implement the critical-use exemption are binding in domestic courts.” Maj. Op. at 9. Second, and, in my view, most important, the disputed “decisions” do not shed light on any ambiguous terms in the Protocol:
[T]he details of the critical-use exemption are not ambiguous. They are nonexistent. The “decisions” do not interpret treaty language. They fill in treaty gaps.
Article 2H(5) thus constitutes an “agreement to agree.” ... And the fruits of those agreements are enforceable only to the extent that they themselves are contracts. There is no doubt that the “decisions” are not treaties.
Maj. Op. at 10. As I see it, these two points control our disposition of petitioners’ claim on the merits.
Absent procedural defaults, the Supreme Court has indicated that “we should give respectful consideration to the interpretation of an international treaty rendered by an international court with jurisdiction to interpret such.” Breard v. Greene, 523 U.S. 371, 375, 118 S.Ct. 1352, 140 L.Ed.2d 529 (1998) (per curiam). As the majority opinion makes clear, however, the disputed “decisions” in this case do not involve “interpretations” of a treaty “by an international court with jurisdiction to interpret such.”
The Supreme Court has yet to explain whether, “once the United States undertakes a substantive obligation (as it did in the Vienna Convention), and at the same time undertakes to abide by the result of a specified dispute resolution process (as it did by submitting to the [International Court of Justice’s] jurisdiction ...), it is bound by the rules generated by that process no less than it is by the treaty that is the source of the substantive obligation.” Medellin v. Dretke, 544 U.S. 660, 683, 125 S.Ct. 2088, 161 L.Ed.2d 982 (2005) (O’Connor, J., dissenting). In other words, it is unclear whether a judgment by a body such as the ICJ, “decided on the back of a *234self-executing treaty, ... must be given effect in our domestic legal system just as the treaty itself must be.” Id. The bewildering array of views found in the per curiam, concurring, and dissenting opinions filed in Medellin make it clear that the Court has not yet come to grips with this issue. Nor do we.
The majority opinion should not be taken to suggest that this court’s decision in Committee of United States Citizens Living in Nicaragua v. Reagan, 859 F.2d 929 (D.C.Cir.1988), offers an answer to the perplexing issue that was skirted in Medellin. Committee of United States Citizens does not address the issue that was left open in Medellin, nor does it address the issue raised by petitioners in this case.
The dispute in Committee of United States Citizens originated with
a 1986 decision by the International Court of Justice (ICJ), which held that America’s support of military actions by the so-called “Contras” against the government of Nicaragua violated both customary international law and a treaty between the United States and Nicaragua. The ICJ concluded that the United States “is under a duty immediately to cease and to refrain from all such acts as may constitute breaches of the foregoing legal obligations.” ...
Prior to the ICJ’s decision, the United States withdrew from the merits phase of the court’s proceedings, contending that the court lacked jurisdiction over Nicaragua’s application.... [T]he President [then] requested and Congress ... approved continued funding for the Contras of the sort that the ICJ found illegal. ...
Unhappy with their government’s failure to abide by the ICJ decision and believing that continued funding of the Contras injures their own interests, appellants filed suit in the United States District Court for the District of Columbia. The suit sought [inter alia ] injunctive and declaratory relief against the funding of the Contras on grounds that such funding violates ... Article 94 of the U.N. Charter....
859 F.2d at 932. The court rejected this claim on narrow grounds:
Since appellants allege that Congress has breached Article 94, we must determine whether such a claim could ever prevail. The claim could succeed only if appellants could prove that a prior treaty — the U.N. Charter — preempts a subsequent statute, namely the legislation that funds the Contras. It is precisely that argument that the precedents of the Supreme Court and of this court foreclose. We therefore hold that appellants’ claims based on treaty violations must fail.
Id. at 937.
There is no suggestion in the present case that Congress modified or denounced the disputed Protocol and that, as a result, a prior treaty obligation has been overridden by a subsequent act of Congress. See Diggs v. Shultz, 470 F.2d 461, 466-67 (D.C.Cir.1972) (“Congress can denounce treaties if it sees fit to do so, and there is nothing the other branches of government can do about it.”), overruled on other grounds, Dellums v. U.S. Nuclear Regulatory Comm’n, 863 F.2d 968 (D.C.Cir.1988). The decision in Committee of United States Citizens is therefore inapposite.
Petitioners’ claim in this ease seems more akin to the claim raised in Day v. Trans World Airlines, Inc., 528 F.2d 31 (2d Cir.1975). The dispute in Day concerned whether an airline was liable for damages to passengers who were injured during a terrorist attack while waiting to board an international flight after surrendering their tickets and passing through *235passport control. The Warsaw Convention assigns liability to the airline for injuries sustained “on board the aircraft or in the course of any of the operations of embarking or disembarking.” Id. at 33. TWA argued that the Warsaw convention did not apply because the passengers had not started the embarking process that, in their view, began when a passenger “steps through the terminal gate.” Id. The court looked to a subsequent agreement entered into by the world’s major airlines as clear evidence that the purpose of the Warsaw Convention was to provide maximum protection to the passengers.
Those called upon to construe a treaty should ... strive to give the specific words of a treaty a meaning consistent with the genuine shared expectations of the contracting parties. These expectations can, of course, change over time. Conditions and new methods may arise not present at the precise moment of drafting.... The conduct of the parties subsequent to ratification of a treaty may, thus, be relevant in ascertaining the proper construction to accord the treaty’s various provisions.
In divining the purposes of the Warsaw treaty, we find the adoption in 1966 of the Montreal Agreement particularly instructive. This Agreement did not alter the language of Article 17 of the Warsaw Convention. But it provides decisive evidence of the goals and expectations currently shared by the parties to the Warsaw Convention.
Id. at 35-36 (internal quotation and citation omitted). But see Buonocore v. Trans World Airlines, Inc., 900 F.2d 8, 11 (2d Cir.1990) (noting that Day had come “under some criticism over the years on the ground that it construed Article 17 too broadly in favor of liability”). Even the broadest reading of Day, however, offers no solace for petitioners in this case.
In Day, the court was asked to divine the meaning of an ambiguous term of the Warsaw Convention and then to enforce the term in accordance with the parties’ intent. In this case, the disputed “decisions” do not purport to interpret any treaty language, nor do they purport to adjudicate disagreements between the parties over the meaning of the Protocol. The Protocol provision upon which petitioners rely is nothing more than an “agreement to agree.” Therefore, on the facts of this case, we have no authority to address a claim that rests on side agreements that extend beyond the enforceable terms of the Protocol.
In sum, we do not decide here whether, once the United States undertakes a substantive obligation in a treaty, and at the same time undertakes to abide by the result of a specified dispute resolution process before an international tribunal, it is bound by the judgments of the tribunal no less than it is by the treaty that is the source of the substantive obligation. That question is not before us.