Costco’s lawsuit urges the federal trade court to declare Trump’s ‘emergency’ tariffs illegal, an authority the president says he has under the International Emergency Economic Powers Act (IEEPA).

Two lower courts have already ruled that Trump exceeded his authority by using emergency powers to impose tariffs.

The case has now reached the Supreme Court, and several companies are trying to protect their rights to refunds should the justices strike down the tariffs.

In the lawsuit filed over the Thanksgiving holiday, Costco said its business had suffered because of the tariffs and was concerned it wouldn’t get its money back even if the apex court upheld previous rulings.

Lawyers for Costco said a “separate action is necessary” as a refund is not guaranteed “in the absence of their own judgment and judicial relief”.