Does Donald Trump have unlimited authority to impose tariffs?

THE ORIGINALIEEPAIEEPAUSMCAIEEPAUSMCA intention was for American presidents to be mere legal executors—not emperors able to impose their will unilaterally. Over time, though, Congress has ceded more and more authority to the executive branch, and the courts, the third coequal branch of government, have happily blessed the arrangement. Nowhere is this clearer than in trade policy.The constitution explicitly grants to Congress the powers “to lay and collect taxes, duties, imposts and excises” and “to regulate commerce with foreign nations”. And yet laws passed over the past century have turned power over to the president to raise and lower tariffs as he sees fit. President-elect Donald Trump is promising to immediately use these powers when he returns to office on January 20th 2025 by imposing tariffs of 25% on and 10% on those from China. Could he really do so?Legally, yes. To get his way Mr Trump could invoke a myriad of legal authorities—some with off-putting three-digit numerical names like Section 232 and Section 301—but the most straightforward would be the International Emergency Economic Powers Act (). This allows the president to impose tariffs with few limits (“to deal with any unusual and extraordinary threat…if the president declares a national emergency with respect to such threat”). has attractive features for Mr Trump. “It’s an emergency power, so there’s minimal procedural requirements. So, he could do it very quickly—on day one, if he wants,” says Warren Maruyama, a former general counsel for the United States Trade Representative. Mr Trump was the first to invoke the law to impose tariffs when, in 2019, he threatened a 5% levy on all Mexican goods in retaliation for illegal migration. And there is another important precedent. In 1971, when Richard Nixon took America off the gold standard and in effect ended the first Bretton Woods system, he imposed an extra 10% duty on all imports by declaring the need “to strengthen the international economic position of the United States” to be an emergency. Courts upheld Nixon’s actions.Constitutional objections—for example, that the president had exceeded the bounds of administrative action—would face an uphill battle, says Kathleen Claussen, a professor of law at Georgetown University. Although American courts have become gradually more sceptical of the administrative state, they have remained deferential to presidents when they invoke national security. In principle, simple majorities in Congress could pass a joint resolution to overturn Mr Trump’s emergency declaration, but in reality a two-thirds majority would be needed to override the president’s inevitable veto. Republicans may even choose to pass some of Mr Trump’s tariffs into law to make fiscal room for the tax cuts they promised, putting them on unquestionable legal ground.The other legal avenues at Mr Trump’s disposal are better tested but slower. Section 301 (of the Trade Act of 1974) was the workhorse of his first administration, used for tariffs on $370bn of Chinese imports (and $7.5bn from the European Union). It could easily be invoked to slap broader tariffs on China but would be less immediately useful for Mexico and Canada, since the president must conduct an investigation and adhere to the long notice-and-comment periods required in American administrative law. Section 232, also deployed during Trump I for steel and aluminium duties, would be less useful for broad tariffs as it needs designation of specific products as threats to national security.Domestic litigation is not all Mr Trump must fend off. America has a free-trade deal with Mexico and Canada called the , negotiated under Mr Trump. It has a dispute-settlement mechanism that Mexico or Canada would undoubtedly invoke if Mr Trump were to go through with his threats. But here, too, would prove useful. Mark Wu, of Harvard Law School, says Mr Trump’s subordinates could point to the national-security exceptions in the deal to argue that they had not violated it. faces a mandatory review (and probable renegotiation) in 2026. A protracted dispute over its fundamental tenets might lead to its collapse.The likeliest constraint on Mr Trump will not be legal. It will be fear of backlash from the markets and the public. “More than half of our fresh fruits and vegetables are from Canada and Mexico…Super Bowl season is right around the corner. Do we really think Trump’s going to impose a 25% guacamole tax on his first day in office?” says Scott Lincicome of the Cato Institute, a libertarian think-tank. He suspects that Mr Trump is issuing tariff threats as a negotiating tactic to force concessions that he can then tout before his inauguration even begins.Mr Trump campaigned on resolving the plight of carworkers, farmers and consumers angry about the price of everyday staples. He would quickly run out of goodwill if he were to make imported goods much more expensive. The court of public opinion is probably the only one that can curb Mr Trump’s instincts.