U.S. appeals court judges sharply questioned on Thursday whether President Donald Trump's tariffs were justified by the president's emergency powers, after a lower court said he exceeded his authority with sweeping levies on imported goods.

Members of the 11-judge panel of the US Court of Appeals for the Federal Circuit in Washington appeared unconvinced by the Trump administration’s insistence that the president could impose tariffs without congressional approval.

U.S. President Donald Trump's overhaul of American trade policy has not gone unchallenged. In the nation's capital on Thursday, appellate court judges expressed broad skepticism around Trump's legal rationale for his most expansive round of tariffs.