President Donald Trump is waging a trade war without getting approval from Congress: He declared a national emergency to slap import taxes — tariffs — on almost every country on earth.

Judges at the U.S. Court of International Trade are set to hear arguments in a case challenging President Donald Trump's tariffs. The lawsuit filed by five domestic businesses argues that the law Trump invoked to impose his "reciprocal" tariffs does not actually give him the power he claims.

In an obscure courthouse in downtown Manhattan, a group of small businesses will take on one of President Donald Trump's boldest uses of executive authority.