The U.S. Supreme Court will soon begin hearing a case on President Donald Trump (photo)‘s ‘country-by-country reciprocal tariffs’ policy. Given that reciprocal tariffs are already in effect and that some countries, including South Korea, have concluded trade agreements with the United States that include tariff rates, confusion appears inevitable if the Court finds the tariffs unlawful.

The New York Times (NYT) reported on the 3rd (local time) that the Court will hold oral arguments on the 5th to hear a case testing the legality of imposing tariffs under the International Emergency Economic Powers Act (IEEPA).

In April, President Trump, asserting that tariffs were needed to resolve the emergency posed by the trade deficit, imposed tariffs of 10~50% on more than 100 countries. He has argued that under the IEEPA, if a ‘national emergency’ is found, the president has authority to impose tariffs.

However, the district and appellate courts ruled that while the IEEPA grants the president authority to restrict imports, it does not extend to authority to impose tariffs.

Legal experts are divided over the concept of an emergency. Tara Lee Grove, a University of Texas law professor, said, “The justices may think it goes too far to define a long-term trade deficit as an emergency.” This suggests the Court may not accept President Trump‘s argument.

By contrast, John Sauer, the U.S. Department of Justice official in charge of litigation, argued, “The courts lack authority to pass judgment on diplomatic situations requiring emergency responses.”

Another issue is whether Congress delegated to the president powers traditionally reserved to the legislature, such as tariffs. Some experts point out, “The word ‘tariff’ never appears in the IEEPA,” and, “Under the U.S. Constitution, only Congress has the power to tax.”

A potential variable is that conservative justices constitute six of the nine on the Court. Conservative justices have tended to accept President Trump‘s arguments in lawsuits challenging the legitimacy of broad exercises of presidential authority.

President Trump has been asserting the legitimacy of his tariff policy day after day. On Truth Social the previous day, he said of the Supreme Court hearing, “It will be one of the most important and consequential rulings in the history of the U.S. Supreme Court,” adding, “If a president cannot use the power of tariffs quickly and nimbly, we will be left defenseless.”

If President Trump loses, the U.S. administration, which has collected more than $100 billion (about 144 trillion won) in tariff revenue, could be forced to refund it. Countries that reached tariff agreements with the United States are also expected to face turmoil. The NYT noted, “Refunding tariffs already collected could lead to an economic breakdown akin to the Great Depression, a halt to trade negotiations, and diplomatic difficulties.”

President Trump has stated that even if the Supreme Court invalidates the tariffs, he will maintain the tariff policy by invoking other statutes.