Democrats already had issued 37 subpoenas as part of discovery in the case because a lower court allowed the members of Congress to move forward. But the U.S. Court of Appeals for the District of Columbia Circuit put that on hold and is now reviewing the Justice Department’s appeal.

Attorney Elizabeth Wydra told the appeals court panel that the lawsuit is necessary because Trump isn’t asking for that consent, which nullifies the members of Congress’ ability to vote on it now and in the future.

“The president, because he does not believe that he is accepting prohibited emoluments, is clear that he will not come to Congress to get their consent before accepting them,” Wydra said.

But judges pointed out that the Supreme Court previously has ruled that individual members of a legislature cannot sue to represent the interests of the legislature as a whole. “And in this case, the Constitution gives the interest to Congress, not the individual members,” Judge Thomas B. Griffith said.

“So, go back, get a resolution from the House and the Senate, they do it all the time, and then come and then you can speak for Congress,” Griffith said. “But until then, you can’t. I think that’s the thrust of the argument.”

Justice Department attorney Hashim Mooppan argued that Congress, at a minimum, “has to pass a statute that expressly authorizes a suit against the president of the United States.”

And Mooppan said that the Constitution already prohibits presidents from accepting foreign emoluments without approval from Congress, and the members aren’t interested in approving Trump”s actions.

Wydra countered that any legislative effort, because it affects Trump’s own financial stake in businesses, would require the president to “tie his own hands” or require super majorities in Congress to pass veto-proof legislation.

“That would essentially twist the Constitution, to a degree that the foreign Emoluments Clause becomes unrecognizable” and unenforceable, Wydra said.

The argument left two judges wondering what remedy Congress has, if not a lawsuit, when there are reasons to think a president is violating the Foreign Emoluments Clause, particularly when the Justice Department has argued in other lawsuits that congressional subpoenas are invalid.

“It seems to me one easy answer to that is congressional oversight, but you’re resisting that in other cases. In other cases you’re saying congressional oversight is inappropriate,” Griffith said. “So I’m just wondering: what is Congress to do in a case where it has reasons to think the Emoluments Clause is being violated?”