Who challenged this?
Answer is in the Fox article.
A group of companies in the steel industry, including the American Institute for International Steel (AIIS), then filed a lawsuit last June to argue the tariffs on imported steel had violated the U.S. Constitution because section 232 was an “improper delegation of legislative authority and violates the principles of separation of powers and checks and balances established by the Constitution.”
The “American Institute for International Steel” (AISS)