The Supreme Court struck down President Trump's tariff authority under the International Emergency Economic Powers Act on Friday, ruling 6–3 that the statute's phrase "regulate importation" does not include the power to levy duties without explicit congressional approval. The decision caps a legal battle that wound through the lower courts and landed before the justices in November.
Harvard Law School professor emeritus Alan Dershowitz didn't mince words about the loss. Appearing on Newsmax's "The Record with Greta Van Susteren" on Friday, Dershowitz said the problem wasn't the policy. It was the legal strategy.
"I thought that the lawyers for Trump made the wrong argument to the Supreme Court, and I predicted they were going to lose based on their argument. Look, if you argue that it's fundraising activity by Congress, of course you're going to lose."
His point is sharper than it first sounds, and it matters for what comes next.
According to the Daily Caller, Dershowitz's critique centers on which constitutional provision the Trump legal team built its case around. Article I of the Constitution vests the power to impose duties and taxes in Congress. Congress can delegate that authority to the president, but the power originates on Capitol Hill. If you frame tariffs as a revenue mechanism, you're fighting on Article I terrain, and the president needs a clear statutory delegation to win.
That's the ground Trump's lawyers chose. And that's the ground where the Court buried them.
Dershowitz argued there was another path entirely. Tariffs don't have to be about revenue. They can function as instruments of diplomacy, deterrence, and national security. Framed that way, you're no longer in Article I territory. You're in Article II, where the president's foreign policy authority is at its broadest and Congress's power to constrain it is at its weakest.
"But if you argue that tariffs can be a weapon of foreign policy, a weapon of diplomacy, a weapon of preventing war, then it's an Article II power of the president, and Congress has no power to limit it."
This isn't a novel legal theory. Presidents have wielded economic tools as foreign policy instruments for decades. Sanctions, embargoes, trade restrictions: all of these operate in the gray zone between economic regulation and executive foreign affairs power. The question was always whether tariffs specifically could be pulled into that category. Dershowitz says yes, but only if someone actually makes the argument.
The tariff fight traces back to February, when Trump imposed duties on Canada, China, and Mexico, tying the action to the fentanyl crisis ravaging American communities. In April, he unveiled a second wave of trade penalties, setting a baseline 10% tariff on imported goods with scaled rates climbing higher based on each nation's trade relationship with the United States.
The legal challenges came fast. By August, the U.S. Court of Appeals for the Federal Circuit had affirmed a lower court ruling halting the tariff policy. The Supreme Court took up the dispute and heard arguments in November.
Friday's 6–3 ruling sided with the lower courts: IEEPA doesn't authorize tariffs. The statute allows the president to regulate importation during emergencies, but the Court drew a line between regulating the flow of goods and imposing duties on them. Without Congress explicitly granting that taxing power, the executive branch can't claim it by inference.
The ruling is a setback, but Dershowitz sees it as a closed door, not a dead end. He noted that Trump himself seemed to signal a shift in framing during press conferences on Friday, characterizing the president's remarks as an acknowledgment that "we may have gone under the wrong statute."
Dershowitz laid out what a recalibrated approach could look like. Rather than invoking IEEPA to impose broad duties, the president could deploy tariffs explicitly as foreign policy tools: steep penalties on Iran to prevent a war, targeted trade measures to enforce compliance with American diplomatic objectives.
"It becomes within the president's power, and I think he can still do it within limits. There are things he can't do. He can't tax or impose a duty without congressional delegation, but he can use the tariff as a foreign policy and military and diplomatic weapon."
The distinction matters enormously. A tariff designed to raise revenue or rebalance trade deficits is a tax, and taxes belong to Congress. A tariff designed to coerce a hostile nation into abandoning its nuclear program or complying with American security demands starts to look like something else entirely.
What Friday's ruling really exposed is a tension that has been simmering for years: where does Congress's power over commerce end and the president's power over foreign affairs begin? The Court answered narrowly, holding that this particular statute doesn't grant this particular power. It did not rule that a president can never use tariffs as foreign policy instruments. It ruled that IEEPA isn't the vehicle.
That leaves room. Congress could pass legislation explicitly delegating tariff authority tied to national security. The executive branch could pursue the Article II theory Dershowitz outlined, daring the courts to strip a president of tools that look indistinguishable from sanctions. Either path requires a fight, but neither path is foreclosed.
The conservative legal movement has spent decades arguing that the executive branch's foreign affairs powers are broad, inherent, and resistant to congressional micromanagement. If tariffs are reframed as instruments of that power rather than disguised tax policy, the constitutional argument changes fundamentally.
Dershowitz predicted this loss. He also predicted there's a way forward. The question now is whether the next round of lawyering matches the ambition of the policy.
