Powers on trial :Trump’s tariffs face reckoning

•On November 5, the US Supreme Court will begin hearing arguments over the legality of President Donald Trump’s sweeping global tariffs. While the case is ostensibly about trade, the broader issue is presidential power — and whether the Court is finally willing to set limits on it.

Trump has repeatedly invoked “emergencies” to justify actions that expand executive authority at the expense of Congress and the courts. He has sent troops to U.S. cities, deported non-citizens without due process under an 18th-century law, and imposed tariffs far beyond what previous presidents have claimed authority to do.

The latest dispute arises from Trump’s use of the International Emergency Economic Powers Act (IEEPA) of 1977 to impose blanket tariffs on nearly every country in the world. Three lower courts have already ruled that this law does not grant the president such powers. The Supreme Court must now decide whether Trump’s expansive reading of “emergency” is legally sound — or an abuse of power.

The powers Trump claims

The US Constitution assigns Congress the authority to set tariffs. However, since the 1930s, Congress has delegated some flexibility to presidents, allowing them to adjust tariffs in specific circumstances, especially to protect industries vital to national security.

Trump’s actions, however, go further than any president before him. His targeted tariffs on steel and aluminium rely on Section 232 of the Trade Expansion Act, which allows such measures for national defence. But to justify blanket tariffs on entire nations — not specific products — Trump turned to the IEEPA, a law intended for crises involving hostile foreign powers, terrorism, or other extraordinary threats.

Under the IEEPA, a president may block transactions or freeze assets in response to an “unusual and extraordinary threat” originating “in whole or substantial part outside the United States.” Historically, presidents have used it to sanction countries like Iran or Russia, not to reshape global trade.

Trump initially claimed his tariffs on Canada, Mexico, and China were necessary to curb the flow of fentanyl into the US — a drug responsible for more than 70,000 overdose deaths annually. Yet less than one per cent of fentanyl entering the country comes from Canada. Later, he broadened the justification: the US trade deficit, he declared, was itself “an unusual and extraordinary threat to national security.”

That trade deficit has existed since 1976 — and actually widened during Trump’s first administration.

The case before the courts

A coalition of small businesses hurt by the 2025 tariffs is suing the Trump administration, arguing the president exceeded his legal authority. They are backed by a bipartisan group of legal scholars.

Two federal courts and the US Court of International Trade have already sided with the plaintiffs, ruling that the IEEPA does not permit tariff-setting. The law’s legislative history supports that view: Congress passed the IEEPA in 1977 to limit presidential power after Watergate-era abuses.

Lawmakers at the time made clear that national emergencies were to be “rare and brief” — not tools for addressing “normal, ongoing problems” like trade deficits.

The Trump administration, however, contends that the IEEPA is an extension of the 1917 Trading with the Enemy Act, which President Richard Nixon used in 1971 to impose a 10% import surcharge during an economic crisis. Because those tariffs were upheld, the administration argues, Trump’s are valid too.

Legal scholars reject that reasoning. The 1977 reforms explicitly separated emergency economic powers from wartime authorities and imposed new procedural limits on their use. In other words, the IEEPA was meant to prevent the very kind of unilateral economic interventions Trump has attempted.

What the court might do

Trump’s public comments suggest he is aware of the case’s broader stakes. He has warned that overturning his tariffs would “literally destroy the United States of America.” He argues that tariffs have generated billions in revenue and claims they helped end “five of the eight wars” he inherited. “If they take away tariffs,” he said recently, “they’ve taken away our national security.”

The court’s conservative majority — which has generally favoured a strong executive — may find these arguments persuasive. Yet there are signs it could draw the line where unchecked presidential power threatens economic orthodoxy.

In a recent decision, the court upheld Trump’s authority to fire leaders of certain independent agencies but carved out protections for Federal Reserve officials, citing the Fed’s “distinct historical tradition.” That same reasoning could apply here: allowing a president to impose unlimited taxes without congressional approval might violate the Constitution’s separation of powers.

If the court strikes down the tariffs, the economic consequences could be turbulent. It would weaken U.S. leverage in trade negotiations and could lead to massive refund claims from importers. Still, many legal analysts argue that restoring constitutional balance outweighs short-term disruption.

Even if Trump loses, he is unlikely to abandon tariffs as a core policy tool. His administration has already pledged to find “other legal avenues” to achieve the same effect.

Ultimately, the significance of this case may not lie in the tariffs themselves but in whether the Supreme Court finally recognises and enforces a limit to presidential power.

The Conversation