Outweighs on magnitude—risks retaliation against the whole country, while status quo federalism gives the states the leverage to act on climate, human rights, etc.

2. The Danger of Retaliation against the Entire Nation Above all, however, the Framers stressed a concern at the outset that continues to be politically relevant today: "that the peace of the WHOLE ought not to be left at the disposal of a PART," for "[t]he union will undoubtedly be answerable to foreign powers for the conduct of its members."107 State involvement in the international realm risks conflicts with nations that may retaliate—economically, militarily, or otherwise—against the United States as a whole.108 For the Framers, this was no hypothetical danger. Their experience under the Articles of Confederation underscored the very real threats and concrete retaliatory conduct, including war, that state disregard of national treaty obligations had provoked. Since 1789, the Supreme Court has consistently echoed the same concerns. In 1832, in Brown v. Maryland,109 the Court struck down a Maryland law that required licenses for certain imports, emphasizing that the state law at issue could spark disputes with other nations. "What answer," Chief Justice Marshall asked, "would the United States give to the complaints and just reproaches to which such an extraordi¬nary circumstance would expose them? No apology could be received, or even offered."110 It is one thing, the Court has suggested, for a state to expose itself to the risks of conflict with a foreign power, but it is quite another to arrogate to itself the power to expose its fellow states to those risks. Hence, in the same vein, the Court in 1875 struck down a California law that in effect regulated immi¬gration, and by implication, commerce with foreign nations. The injured nation could not direct a claim for redress to California, the Court observed, because California could: hold no exterior relations with other nations. It [the foreign claim] would be made upon the government of the United States. If that government should get into a difficulty which would lead to war, or to suspension of intercourse, would California alone suffer, or all the Union?111 A century later, in 1979, California imposed an ad valorem property tax on foreign-owned cargo containers. The Court again invalidated the state law, mind¬ful that the "risk of retaliation by Japan ... [was] acute, and such retaliation of necessity would be felt by the Nation as a whole."112 The Court's concerns in this regard are now embodied in the so-called "one voice" doctrine—a putative requirement, inferred from the Constitution's text and structure, that the nation speak with one voice in the realm of foreign affairs. The one-voice doctrine often reflects a reasonable national interest in bolstering the efficacy of American foreign policy. The national interest sometimes benefits from at least the appearance of national unity and popular support. Open conflict between the federal and state governments on key foreign policy questions can undermine national foreign policy objectives. Of course, sometimes the foreign policy of the federal government is less than clear. Yet the federal government’s silence with respect to a particular issue of foreign policy does not neces¬sarily imply an absence of a federal policy. Still less does it indicate that the states should feel free to enter the field. Federal silence, inaction, or ambiguity may be calculated. Sometimes the best policy is to do and say nothing, or deliberately to attempt, with nuance, to leave national policy unclear.113 But the question is whether the doctrine has been expanded beyond the limit of its logic.114

the state with some marginal benefit (e.g., [*785] investment or trade opportunities) that impedes the realization of collective goods by the United States. n303