WASHINGTON (AP) -- Costco is joining other companies that aren't waiting to see whether the Supreme Court strikes down President Donald Trump's most sweeping import taxes. They're going to court to demand refunds on the tariffs they've paid.

The U.S. Court of International Trade and the U.S. Court of Appeals for the Federal Circuit in Washington ruled earlier this year that Trump's biggest and boldest import taxes are illegal. The case is now before the Supreme Court. In a Nov. 5 hearing, several of the high court's justices expressed doubts that the president had sweeping power to declare national emergencies to impose tariffs on goods from almost every country on earth.

If the court strikes down the tariffs, importers may be entitled to refunds on the levies they've paid. "It's uncertain whether refunds will be granted and, if so, how much,'' said Brent Skorup, a legal fellow at the libertarian Cato Institute. "But the possibility has prompted many companies -- including Costco -- to file actions in the U.S. Court of International Trade to get in line, so to speak, for potential refunds.''

In a complaint filed last week with the U.S. Court of International Trade in New York, Costco said it is demanding the money back now "to ensure that its right to a complete refund is not jeopardized.? The operator of warehouse-sized stores expressed concern that it could not get a refund once the tariff bills have have gone through liquidation by Customs and Border Protection, a process Costco says will start Dec. 15.

Revlon and canned seafood and chicken producer Bumble Bee Foods have made similar arguments in the trade court.

The tariffs facing the court challenged have raised around $90 billion so far. Trump warned back in August that the loss of his tariffs would destroy that American economy and lead to "1929 all over again, a GREAT DEPRESSION!"