WASHINGTON, Dec. 2 (Xinhua) -- Multinational retail giant Costco has filed a lawsuit seeking to secure a full refund of import duties should the U.S. Supreme Court strike down President Donald Trump's use of emergency powers to impose tariffs.

In a complaint lodged with the Court of International Trade over the Thanksgiving holiday, the retailer asked judges to declare all tariffs imposed under the International Emergency Economic Powers Act unlawful.

The company argued that Trump exceeded his authority when he used the statute to levy what he described as "reciprocal" tariffs, a move two lower courts have already found improper.

Costco said its business had been harmed by the duties and warned that, even if the Supreme Court ultimately agrees the tariffs were illegal, a refund is not guaranteed without its own separate legal action.

The company did not disclose how much it aims to recover, but trade data from the U.S. customs agency show importers have paid roughly 90 billion U.S. dollars in related tariffs as of late September. ■