Washington, Nov 5 (AP) President Donald Trump's power to unilaterally impose far-reaching tariffs is coming before the Supreme Court on Wednesday in a pivotal test of executive power with trillion-dollar implications for the global economy.

The Republican administration is trying to defend the tariffs central to Trump's economic agenda after lower courts ruled the emergency law he invoked doesn't give him near-limitless power to set and change duties on imports.

The Constitution says Congress has the power to levy tariffs. But the Trump administration argues that in emergency situations, the president can regulate importation taxes like tariffs. Trump has called the case one of the most important in the country's history and said a ruling against him would be “catastrophic” for the economy.

The challengers argue the 1977 emergency-powers law Trump used doesn't even mention tariffs, and no president before has used it to impose them. A collection of small businesses says the uncertainty is driving them to the brink of bankruptcy.

The case centres on two sets of tariffs. The first came in February on imports from Canada, China and Mexico after Trump declared a national emergency over drug trafficking. The second involves the sweeping “reciprocal” tariffs on most countries that Trump announced in April.

Multiple lawsuits have been filed over the tariffs, and the court will hear suits filed by Democratic-leaning states and small businesses focused on everything from plumbing supplies to women's cycling apparel.

Lower courts have struck down the bulk of his tariffs as an illegal use of emergency power, but the nation's highest court may see it differently.

Trump helped shape the conservative-majority court, naming three of the justices in his first term. The justices have so far been reluctant to check his extraordinary flex of executive power, handing him a series of wins on its emergency docket.

Still, those have been short-term orders — little of Trump's wide-ranging conservative agenda has been fully argued before the nation's highest court. That means the outcome could set the tone for wider legal pushback against his policies.

The justices have been sceptical of executive power claims before, such as when then-President Joe Biden tried to forgive USD 400 billion in student loans under a different law dealing with national emergencies. The Supreme Court found the law didn't clearly give him the power to enact a program with such a big economic impact, a legal principle known as the major questions doctrine.

The challengers say Trump's tariffs should get the same treatment, since they'll have a much greater economic effect, raising some USD 3 trillion over the next decade. The government, on the other hand, says the tariffs are different because they're a major part of his approach to foreign affairs, an area where the courts should not be second-guessing the president.

The challengers are also trying to channel the conservative justices' scepticism about whether the Constitution allows other parts of the government to use powers reserved for Congress, a concept known as the nondelegation doctrine. Trump's interpretation of the law could mean anyone who can “regulate” can also impose taxes, they say.

The Justice Department counters that legal principle is for governmental agencies, not for the president.

If he eventually loses at the high court, Trump could impose tariffs under other laws, but those have more limitations on the speed and severity with which he could act. The aftermath of a ruling against him also could be complicated, if the government must issue refunds for the tariffs that had collected USD 195 billion in revenue as of September.

The Trump administration did win over four appeals court judges who found the 1977 International Emergency Economic Powers Act, or IEEPA, gives the president authority to regulate importation during emergencies without explicit limitations. In recent decades, Congress has ceded some tariff authority to the president, and Trump has made the most of the power vacuum. (AP) SKS SKS

Executive emergency power test may determine presidential authority to impose tariffs and reshape international trade practice. Whether the president may unilaterally impose sweeping import duties under emergency authority is presented as a central constitutional question testing the scope of executive emergency power to regulate importation without explicit congressional authorization. Challengers argue the emergency statute does not authorize tariffs and invoke the major questions doctrine and nondelegation concerns; the government contends emergency import regulation is within presidential authority and entwined with foreign affairs, with significant remedial and economic consequences if invalidated.