In a decision with sweeping constitutional implications, the Supreme Court shut down President Trump’s attempt to use the International Emergency Economic Powers Act (IEEPA) as a blank check for tariffs imposed in the name of “emergency.”

The justices rejected the claim that the statute quietly granted the presidency the authority to impose import duties at will and to reshape the global economy by executive decree. The language of IEEPA contains no such boundless delegation, and the court declined to manufacture one, treating Trump’s theory of power no differently than it treated former President Biden’s executive overreaches in cases such as West Virginia v. Environmental Protection Agency.

To understand the decision’s importance, one must consider the counterfactual. Asteroids that sail well clear of Earth do not garner much thought. Had the Supreme Court concluded otherwise, though, the ruling would have shaken the American political-constitutional architecture to its foundations.

The Constitution confers powers to levy tariffs and to “regulate Commerce with foreign Nations” to Congress. “We have long expressed ‘reluctance to read into ambiguous statutory text’ extraordinary delegations of Congress’s powers,” Chief Justice John Roberts wrote.

The White House perceived a perfect image of unbounded tariff authorities in statutory language equivalent to a Wooly Willy portrait. Allowing presidents to carry on in this mode of assuming vast, heretofore unthought-of powers would amount to a fundamental rebalancing of the constitutional order, moving substantial weight from Congress — the preeminent branch of American government — to an office occupied by a single man.

Under Trump’s theory, each successive administration could, without any check from the judiciary, arrogate to itself new powers to further its own boutique political aims, however unpopular. “A ruling for him here, the President acknowledges, would afford future Presidents the same latitude he asserts for himself,” Justice Neil Gorsuch wrote in his concurring opinion. “So another President might impose tariffs on gas-powered automobiles to respond to climate change. Or, really, on virtually any imports for any emergency, any President might perceive.”

An America governed on the basis of vague emergency powers, according to the will of the one in 340 million Americans who happens for the moment to sit behind the Resolute Desk, falls far from the system of popular self-governance crafted in Independence Hall in the hot summer of 1787.

Judges ought to rule primarily on the black-letter law found in the Constitution and in ordinary statutes, and not on abstract principles excavated from the penumbras and emanations formed from their private readings of legal documents. It happens, however, that the text of the Constitution and the principles on which it rests bar the assumption of legislative powers by the executive.

“All legislative Powers herein granted shall be vested in a Congress of the United States,” reads the very first sentence of the body of the Constitution. The Framers knew that any branch of government’s exercise of the powers entrusted to others would invite abuse. As James Madison wrote in Federalist No. 47, “The accumulation of all powers, legislative, executive, and judiciary, in the same hands … may justly be pronounced the very definition of tyranny.”

Although the Madisonian apportionment of powers endures only in part today, the Supreme Court’s ruling warded off a legal theory that threatened further damage to the artifice.

Much uncertainty remains. In the wake of the Supreme Court’s ruling, Treasury Secretary Scott Bessent has indicated that refunds of illegally collected tariff revenues may not be issued by the administration without protracted litigation. Indeed, this litigation has already commenced.

The White House, moreover, announced a universal 10 percent tariff under Section 122 of the Trade Act of 1974. “These new tariffs are even more clearly illegal than Trump’s IEEPA tariffs,” as asserted by National Review’s Andrew McCarthy.

Further litigation will ensue, and notwithstanding its resolution, the American legal system — not to mention American businesses — will, perforce, endure the resulting tribulations.

Politics is not the art of the endgame; it offers no chance for final victories, only incremental and temporary successes in pursuit of a more perfect union. For the moment, the judiciary has performed its function: the executive has “been restrained from oppression,” to employ the verbiage of the Virginia Declaration of Rights. Tomorrow will bring new litigation challenging new overreaches, as Trump replays his predecessor’s bid to circumvent a Supreme Court decision by inventing new powers under new statutes. (Trump, tragicomically, seems destined to mimic the governance and to share in the fate of his political foils.)

For today, the Supreme Court has done its duty. There is good cause to hope that it will continue to do so.

David McGarry is research director at the Taxpayers Protection Alliance.