Ahead of the Supreme Court’s ruling on the legality of President Donald Trump’s most sweeping import taxes, Costco is joining other companies in going to court to demand refunds on the tariffs they’ve already paid, the Associated Press reported. Submitted last week with the trade court in New York, Costco is the largest company yet to file suit.

Earlier this year, the specialized U.S. Court of International Trade in New York and the U.S. Court of Appeals for the Federal Circuit in Washington ruled that Trump’s biggest import taxes are illegal, a case that is now in front of the Supreme Court.

The Constitution grants Congress the power to impose tariffs under the 1977 International Emergency Economic Powers Act (IEEPA). But as President, Trump claims that he has an almost unlimited right to impose tariffs.

“Because IEEPA does not clearly authorize the President to set tariffs ... the challenged tariff orders cannot stand and the defendants are not authorized to implement and collect them,” Costco's lawyer wrote in the lawsuit, NBC News reported.

If the court overturns the tariffs, importers may be entitled to refunds on the levies they’ve already paid. Trade lawyer Joyce Adetutu, a partner at the Vinson & Elkins law firm, told AP that Costco is trying to “make sure that if and when the Supreme Court overturns the IEEPA tariffs, which could come as late as the summertime, they have the judgment in place’’ and can collect a refund.

The complaint itself said that Costco is demanding the money back now “to ensure that its right to a complete refund is not jeopardized.” The wholesale company also expressed concern that it might struggle to receive a refund once its tariff bills have been finalized.

Costco did not specify how much it has paid in duties so far, NBC News reported, but importers have paid nearly $90 billion under the IEEPA law, according to U.S. Customs and Border Protection data through late September.

According to NBC, other companies that have filed similar suits are cosmetics manufacturer Revlon, eyeglasses maker EssilorLuxottica, motorcycle manufacturer Kawasaki, canned foods seller Bumble Bee, Japanese auto supplier Yokohama Tire and many smaller firms.