Small business importers and the US Justice Department clashed Thursday over whether President Trump has the authority to impose his “Liberation Day” tariffs just hours before those duties were scheduled to take effect for countries around the world.

The confrontation took place in Washington, D.C. before a panel of 12 judges at the Circuit Court of Appeals for the Federal Circuit, and it did not produce an immediate ruling.

But it did reveal that some judges have some skepticism of the Justice Department’s arguments that the president can unilaterally impose wide-ranging, global tariffs by invoking a law enacted in 1977 to protect the US from international threats, while others found support for the claim.

That law, known as “IEEPA” — the International Economic Emergency Powers Act — authorizes the president to “regulate” international commerce after declaring a national emergency.

The panel — composed of eight judges appointed by former Democratic presidents and four appointed by Republican presidents — spent considerable time asking the lawyers what Congress meant when it wrote in IEEPA that presidents have authority to “regulate importation.”

“IEEPA doesn’t even say ‘tariffs.’ It doesn’t even mention it,” one judge said.

President Donald Trump holds up the first list of proposed ‘reciprocal tariffs’ on April 2, during an event the president dubbed as ‘Liberation Day.’ (Photo by Chip Somodevilla/Getty Images) · Chip Somodevilla via Getty Images

“What does ‘regulation of importation’ mean?” another judge asked. And “If ‘regulate’ doesn’t cover tariffs, what does it cover?”

A lawyer for one of 12 states joining the small businesses in their challenge of Trump’s tariffs, Brian Simmonds Marshall, said he thought the phrase was meant to permit the president to order quotas that limit the number of imported goods, and potentially for the president to order import licensing requirements and fees.

But “the one thing that I think it excludes for sure is tariffs,” Simmonds Marshall added.

But Trump’s Justice Department assistant attorney general Brett Shumate said that IEEPA doesn’t have such limits and that Congress would have understood that when it wrote the law.

And while IEEPA offers the president broad power, Shumate said that power is not unlimited because it is available only during a national emergency, and Congress can step in and overrule the president.

“The primary rule is for Congress to check the president if there is an abuse of the IEEPA tariff authority,“ Shumate said.

Trump and Nixon

The judges also questioned if a Nixon-era case that addressed IEEPA’s predecessor law, known as the Trading with the Enemy Act (TWEA), put limits on what a president can do under IEEPA.

Trump’s team has been citing that 1970s case as proof that the president’s global tariffs should be allowed to stand in court.