Washington: The U.S. Supreme Court ruled against President Donald Trump's sweeping emergency tariffs, dealing a major setback to his economic policy and prompting questions over trade deals with South Korea and other partners that he has secured with the duties as a key negotiating tool.

According to Yonhap News Agency, the high court's six-to-three decision upheld a lower court's ruling against Trump's use of the 1977 International Emergency Economic Powers Act (IEEPA) to justify duties, including "reciprocal" tariffs on South Korea and other countries. This decision has raised expectations that Washington would have to initiate a complex tariff refund process.

The Trump administration had imposed reciprocal tariffs of 15 percent on South Korean products, reduced from 25 percent following a bilateral agreement under which Seoul committed to investing US$350 billion in the United States, among other pledges, in return for the tariff reduction.

Trump has used the IEEPA tariffs for various purposes, including pressuring countries like Mexico, Canada, and China to help end the flow of fentanyl into the U.S. and securing trade deals with South Korea, Japan, the European Union, and others, as well as curbing India's purchases of Russian oil.

The ruling does not impact Trump's entire tariff policy. It does not cover other levies, including sector-specific tariffs imposed under Section 232 of the 1962 Trade Expansion Act, which allows the president to adjust imports if they threaten national security.

Prior to the court decision, Trump warned of serious consequences if the IEEPA tariffs were undone, suggesting it would be a significant threat to U.S. national security or a detrimental blow to America.

The Trump administration is expected to explore workarounds or other legal avenues to maintain the tariffs. It may consider provisions such as Section 232 for sector-specific tariffs, Section 301 of the 1974 Trade Act for country-specific tariffs against trade violations, and Section 338 of the 1930 Tariff Act for duties against countries with discriminatory trade practices.

Uncertainty persists over whether Trump would push for new tariffs as his administration faces the politically sensitive issue of "affordability" ahead of the midterm elections, which are viewed as a measure of public sentiment on his administration's performance.

Ahead of major local elections in June, South Korean President Lee Jae Myung could face domestic pressure to reconsider the trade deal with Washington in light of the court ruling, according to Victor Cha, president of the geopolitics and foreign policy department and Korea chair at the Center for Strategic and International Studies.

On April 2, a day Trump called "Liberation Day," he announced his tariff plans, arguing that a lack of "reciprocity" in trade with partners led to "large" and "persistent" trade deficits, posing an "unusual" and "extraordinary" threat to U.S. national security.