The rulings against the levies in two federal courts – the U.S. Court of International Trade and the U.S. District Court in Washington, D.C. -- centered on Trump's unprecedented invocation of the International Economic Emergency Powers Act as a legal justification for tariffs.

President Donald Trump returned to the White House in January determined to overturn decades of American policy and build a tariff wall around a U.S. economy that used to be pretty much wide open to foreign products.