What may be the biggest battle yet in Donald Trump's trade war is about to begin. The Trump administration heads to the US Supreme Court on Wednesday, facing off against small businesses and a group of states who contend most of the tariffs it has put in place are illegal and should be struck down. If the court agrees with them, Trump's trade strategy would be upended, including the sweeping global tariffs he first announced in April. The government would also likely have to refund some of the billions of dollars it has collected through the tariffs, which are taxes on imports.