A trade group sued the Trump administration over the imposition of a 25 percent tariff on imported steel, seeking a court declaration that the move is unconstitutional and an order blocking the duty.

The American Institute for International Steel and two of its member companies filed suit Wednesday in the U.S. Court of International Trade in New York. They alleged that the 1962 law used by Trump to impose the tariff violates a constitutional provision that bars Congress from delegating its legislative powers to the president.

The group said the so-called 232 statute, which allows the president to impose unlimited tariffs or create other trade barriers if he believes they are needed to protect national security, is unconstitutional because it places no limits on his discretion.

“The law allows the President to consider virtually any effect on the U.S. economy as part of national security,” the group’s president, Richard Chriss, said in a statement.

The suit comes as Republican senators including Bob Corker of Tennessee and Orrin Hatch of Utah have indicated they will attempt to limit Trump’s authority to impose tariffs on national-security grounds. Hatch has long opposed tariffs, specifically the use of the 232 statute.

The case is American Institute for International Steel v U.S., 18-cv-00152, U.S. Court of International Trade.