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On Tuesday, President Donald Trump said he has already told his team to consider a ban on diesel exports. Treasury Secretary Scott Bessent said officials are studying whether a full or partial ban would work without wrecking U.S. refining. Trump said a decision would come “fast, one way or the other.”
The pressure is easy to see from a truck cab. The national average for on-highway diesel hit about $6.53 a gallon this week, a new high. That is roughly $3 more than a year ago. In some states, the pain is worse. California has been well above $8. Farm groups and trucking-heavy states say the cost is crushing harvest work, grocery distribution, and long-haul freight. Republican lawmakers from Iowa, Alaska, Tennessee, and other states have called for a pause on exports. One House bill would shut off diesel exports through early 2027. Another would trigger a ban whenever the national average hits $5 a gallon.
The idea is simple. The United States makes more diesel than it burns at home. Refiners have been sending large volumes abroad, often more than a million barrels a day, and at times closer to 1.6 million. Supporters say keeping that fuel here would rebuild inventories and knock down pump prices for truckers and farmers. Critics, including oil companies and some of Trump’s own energy officials, say the opposite could happen. If refiners lose their export market, they may cut overall runs. That could mean less gasoline as well as less diesel. Allies in Europe and Latin America that now buy U.S. diesel would also lose supply. Any ban would be the first major limit on U.S. energy exports since Congress ended the old crude-oil export ban in 2015.
That last point matters. Congress no longer gives the president a routine switch to cap petroleum-product exports. If the White House acts on its own, it would almost certainly use emergency law.
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.
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