On the question of President Trump’s emergency tariffs, the Supreme Court has spoken. In the court’s view, the International Emergency Economic Powers Act does not authorize the president to impose tariffs during a declared emergency, namely, the massive trade deficits that threaten our economic security.

But the court’s decision in Learning Resources, Inc. v. Trumpwas highly fractured. Only three justices — Elena Kagan, Sonia Sotomayor, and Ketanji Brown Jackson — held that the law, under normal principles of statutory construction, does not give the president authority to impose tariffs.

A tariff wears two hats. It can function as a tax, but it can also operate as an instrument of foreign policy.

Justice Brett Kavanaugh’s dissent, joined by Clarence Thomas and Samuel Alito, quite persuasively demonstrates why that is not the case. As Justice Thomas noted in his separate dissent, the power to “regulate … importation” has throughout American history “been understood to include the authority to impose duties on imports.”

The other three justices who formed the majority — Chief Justice John Roberts and Justices Neil Gorsuch and Amy Coney Barrett — resorted to the major questions doctrine. This principle of statutory interpretation holds that Congress must speak with super clarity on issues of “economic and political significance” for the Court to approve a delegation to the executive.

The turn to the major questions doctrine implies that the statute, under normal principles of statutory construction, authorizes the president’s action, a point that Justice Gorsuch explicitly conceded in his concurring opinion.

But here’s the rub. The court has never previously applied the major questions doctrine in the foreign policy arena — and for good reason. Under Article II of the Constitution, the president has the core responsibility for foreign policy. Chief Justice Roberts acknowledged as much, stating in the part of his opinion that garnered only three votes that “as a general matter, the President of course enjoys some ‘independent constitutional power[s]’ over foreign affairs ‘even without congressional authorization.'”

That’s quite an understatement. The failure to recognize the full measure of that fundamentally important piece of constitutional law is the first fatal flaw in the chief justice’s opinion.

The key Supreme Court case on this point is United States v. Curtiss-Wright Export Corp. (1936), which Roberts does not mention. In that case, Justice George Sutherland, writing for a near-unanimous court, articulated the principled distinction between foreign and domestic powers: “In this vast external realm, with its important, complicated, delicate and manifold problems, the President alone has the power to speak or listen as a representative of the nation.”

Then, quoting John Marshall’s “great argument of March 7, 1800, in the House of Representatives,” Sutherland added, “The President is the sole organ of the nation in its external relations, and its sole representative with foreign nations.”

The main issue in the case was whether Congress could delegate to the president the authority to prohibit the sale of arms to either side in a war between Bolivia and Paraguay. But Sutherland did not rely solely on the act of Congress. He wrote:

It is important to bear in mind that we are here dealing not alone with an authority vested in the President by an exertion of legislative power, but with such an authority plus the very delicate, plenary and exclusive power of the President as the sole organ of the federal government in the field of international relations — a power which does not require as a basis for its exercise an act of Congress.

In other words, President Roosevelt had the power to ban the sale of arms even without the act of Congress at issue.

The same should be true in Learning Resources, Inc. v. Trump. Thomas’ dissenting opinion convincingly demonstrates why that is the case. While the chief justice claimed that Solicitor General D. John Sauer conceded that “the President enjoys no inherent authority to impose tariffs during peacetime,” that’s not exactly what Sauer said. Rather, he argued that the statute delegated such authority to the president. Under Curtiss-Wright, a claim of inherent authority over foreign policy should still be viable.

In the part of the Curtiss-Wright opinion I elided above, Sutherland noted that the president’s power over foreign affairs, “like every other governmental power, must be exercised in subordination to the applicable provisions of the Constitution.”

For Roberts, the fact that the taxing power is vested exclusively in Congress — and that any bill “for raising revenue” must originate in the House of Representatives — further confirmed that Congress had not delegated to the president any authority to impose tariffs. The point lands a bit oddly, given Roberts’ earlier willingness to treat Obamacare as a tax even though the bill originated in the Senate.

RELATED: ‘Even stronger’: President Trump optimistic even after SCOTUS strikes down tariffs

Photo by Chip Somodevilla/Getty Images

That move exposes the court’s second fatal flaw: a tariff wears two hats. It can function as a tax, but it can also operate as an instrument of foreign policy.

President Trump’s tariffs plainly fell into the latter category, even if they also happened to raise substantial revenue. This dual character is not unique to presidential tariffs; the Constitution itself recognizes it in a related provision. Article I, Section 10, Clause 2 provides that “No State shall, without the Consent of the Congress, lay any Imposts or Duties on Imports or Exports, except what may be absolutely necessary for executing its inspection Laws.”

That clause reflects the same two-hat reality. An impost or duty — akin to a tariff — can be a revenue measure, but it also can serve a regulatory end tied to a state’s police power. Congress’ exclusive authority to impose taxes under Article I, Section 8, does not erase the states’ limited ability to levy duties for a different purpose: enforcing inspection laws to protect health and safety.

So too with tariffs. The fact that duties and imposts fall within Congress’ taxing power does not negate the president’s authority to use tariffs as an instrument of foreign policy — a “plenary and exclusive” power that Curtiss-Wright describes as vested in the president as the nation’s “sole organ” in external affairs.

That distinction drives Thomas’ characteristically insightful dissent. He points, in effect, to a path by which the president may continue using tariffs while negotiating with and responding to foreign nations in his role as the sole organ of American foreign policy. Time will tell whether the court, if the president takes that route, will remain faithful to its landmark Curtiss-Wright precedent. It should.

Editor’s note: A version of this article appeared originally at the American Mind.