经济周刊最高法院对IEEPA

19 December 2025 Richard de Chazal, CFArdechazal@williamblair.com+44 20 7868 4489 Economics Weekly Louis Mukamalmukama@williamblair.com+1 312 364 8867 The Supreme Court on IEEPA: WhatChanges, What Doesn’t William Blair On November 5, the Supreme Court heard oral argumentsin the cases challenging President Trump’s use of emer-gency powers to levy sweeping global tariffs. Justices fromboth ideological camps questioned whether the Interna-tional Emergency Economic Powers Act (IEEPA), common-ly used for sanctions, also allows the president to imposetariffs without congressional approval. Since the cases Should the justices uphold the tariffs, markets would bemostly unfazed as companies have largely adapted to a tradesystem based on higher tariffs, though it would heightenconcerns about how this court may approach other cases onthe limits of presidential authority. A decision prohibitingtariffs under the IEEPA could also trigger refunds to import-ers and revive trade uncertainty as the Trump administra-tion looks to reimpose the measures under a patchwork of President Trump relied on the IEEPA to levy fentanyl traf-ficking-related tariffs on Canada, Mexico, and China and thereciprocal tariffs on imports from most countries to addressthe U.S. trade deficit. Exhibit 2 shows that U.S. Customsand Border Protection (CBP) collected nearly $89 billion A Supreme Court decision against IEEPA tariffs wouldcurb the president’s ability to use tariffs at the same The IEEPA, the law at the center of this case, was enacted in1977 and allows presidents to “regulate … importation or ex-portation” if they declare a national emergency “to deal with Of the more than 120 statutory powers available to thepresident during a national emergency, IEEPA is themost frequently used. Between 1977 and September 1,2025, according to data from the Congressional ResearchServices, presidents have invoked the IEEPA in 77 dec-larations of national emergency, and all but 5 of the 51ongoing emergencies involve it (exhibit 1). The state ofemergency declared by President Jimmy Carter in 1979following the seizure of the U.S. embassy in Tehran was The government opened by defending the president’sbroad authority under the IEEPA, with Solicitor GeneralJohn Sauer arguing that “exploding trade deficits” andfentanyl trafficking posed national emergencies andthat the “regulate … importation” “plainly embraces Before the case was appealed to the Supreme Court, thelower courts agreed with the small businesses and stateschallenging the tariffs that the IEEPA does not authorize William Blair authority to tax and regulate commerce, while JusticeSonia Sotomayor rejected Sauer’s attempt to distinguishtariffs from taxes: “That’s exactly what they are. They’regenerating money from American citizens, revenue.” Theconservation justices also chimed in. Justice Neil Gorsuchwarned that Sauer’s reading of the law risked a “one-wayratchet” of expanding executive power, and Chief Justice Arguing for the plaintiffs, Neal Katyal claimed it was“simply implausible” that Congress intended the IEEPAto let a president “overhaul the entire tariff system,” alsonoting that no president in nearly 50 years had attemptedto use the statute this way. Congress, he said, “knowsexactly how to delegate its tariff powers … always with It may seem surprising that a court that has previouslyexpanded presidential power in other areas would takethis stance, but it becomes more understandable when we Conservative justices pressed him on scale—how theIEEPA could authorize a full embargo but not a tariff—an“odd donut hole” in the law, as Justice Brett Kavanaughput it. Justice Amy Coney Barrett questioned whetherKatyal was reading too many constraints into a statute For example, in 2020 the court allowed the first Trumpadministration to fire the head of the Consumer Finan-cial Protection Bureau, who until then could only beremoved for cause. That same court has also limited ad-ministrations’ policymaking discretion in cases rangingfrom the 2021 decision striking the CDC’s eviction mora-torium, the 2023 decision striking the Biden administra- Barrett also raised the practical problem of reimburs-ing billions in already-paid tariffs, calling it “a completemess,” but Katyal countered that a “specialized body oftrade law” exists to manage reimbursements, even ifthe process is “very complicated.” A messy unwind, heargued, is “not a reason not to act,” and he suggested the The court is likely to rule in a similar way in the IEEPAcase, and that is distinct from cases in which it rules infavor of the administration because it sees Congress as lim-iting the president’s own authority over agencies that are Should the justices strike the IEEPA tariffs, the Trumpadministration has indicated it would move to replicatethem through a range of other trade statutes shown inexhibit 4. Some of these alternatives are familiar and At the oral argument last month, enough justices wereseemingly leaning