Could Washington Ban Diesel Exports? What Truckers Need to Know

What IEEPA is and how it became a tariff machine

The main statute is the International Emergency Economic Powers Act, or IEEPA. Congress passed it in 1977. It lets a president act after declaring a national emergency over an “unusual and extraordinary threat” that comes, in whole or in large part, from outside the United States. Once that emergency is declared, the president can regulate or block many cross-border deals. That includes the import or export of property subject to U.S. jurisdiction. For decades, presidents used IEEPA for sanctions, asset freezes, and export controls. They did not use it to tax imports.

That changed in 2025. Early in his second term, Trump invoked IEEPA to put tariffs on Canada, Mexico, and China, citing fentanyl and border threats. He later used the same law for broad “reciprocal” tariffs tied to a declared emergency over the U.S. trade deficit. No president had used IEEPA that way before. The administration argued that the power to “regulate” importation included the power to put a price on it. Importers and business groups sued. They said tariffs are taxes, and only Congress can tax.

What the Supreme Court did

On Feb. 20, 2026, the Supreme Court agreed with the challengers. In Learning Resources, Inc. v. Trump, the Court ruled 6-3 that IEEPA does not authorize tariffs. Chief Justice John Roberts wrote that the Constitution gives Congress the power to lay duties. IEEPA never mentions tariffs or taxes. The words “regulate … importation,” he wrote, cannot carry the weight of an open-ended tariff power. Until 2025, no president had read the law that way. Customs stopped collecting the IEEPA tariffs almost immediately. Other tariff tools, such as Section 232 national-security duties, were left in place.

The ruling was narrow in an important way. The Court blocked IEEPA as a tax statute. It did not erase IEEPA’s older use: blocking or limiting trade itself. Legal analyses since the decision have stressed that point. The statute still lets a president prohibit exports if the emergency test is met. That is the opening a diesel ban would try to walk through.

How IEEPA would be used to ban diesel exports.

A presidential diesel embargo would not look like a new tax. It would look like a prohibition. The White House would rely on a declared national emergency, either the energy emergency Trump issued in January 2025 or a new one tied to wars that have squeezed global refining, including the conflict with Iran and attacks on Russian plants. An executive order would then tell the Treasury Department and other agencies to stop, license, or sharply limit diesel exports. Companies that shipped anyway could face IEEPA penalties. The ban could be total or partial. It could last weeks or months. Trump and Bessent have already floated both options.

That path is legally cleaner than the tariff experiment, but it is not risk-free. IEEPA still requires a foreign-source threat and measures aimed at that threat. Refiners would have every reason to sue. They would argue a price-relief plan for U.S. truckers is a domestic political fix, not a response to a foreign emergency. Courts might also ask why a ban on American fuel leaving the country deals with wars overseas. Even if the order survives, the market effects would hit freight first. A short-term glut on the Gulf Coast could cut diesel prices in some regions. The East Coast, which already depends on products moving from the Gulf, could see a messier picture. If refiners cut runs, gasoline and diesel could both tighten later.

For freight operators, the legal question is less abstract than it sounds. If Washington can flip an emergency switch on diesel trade, fuel policy becomes another source of rate volatility: fast, political, and hard to plan around. The next signal will not be a floor speech. It will be an executive order citing IEEPA.

Matthew Leffler is a trucking industry expert and an adjunct professor of law at Michigan State University College of Law. He can be reached at matthew@armchairattorney.com.