The U.S. Court of Appeals for the D.C. Circuit's ruling that the House can't sue to compel former White House counsel Donald McGahn's testimony is raising questions for both Capitol Hill and federal judges about the immediate effect it has on lawmakers's ability to go to court.

Those issues were underscored Thursday as a federal judge weighed how the ruling applies to a separate House lawsuit seeking President Donald Trump's federal tax returns. U.S. District Judge Trevor McFadden of the District of Columbia said the McGahn opinion—if it stands—has likely cancelled out the House's arguments in relation to its subpoena on the tax returns.

McFadden stayed the tax returns lawsuit in January ahead of a decision in McGahn, over the standing issues that had been raised in oral arguments in the case.

Friday's 2-1 appeals court ruling found the House Judiciary Committee does not have standing to go to court to enforce a subpoena for McGahn's testimony. With several other House lawsuits pending in the circuit's jurisdiction, the decision could prove fatal to lawmakers' ability to seek judicial review in its fights with the Trump administration.

The House is set to shortly file a petition for en banc rehearing of the Mcgahn case. If the judges agree to a rare full-panel consideration of the lawsuit, they may also vacate the opinion, a point of debate during Thursday's hearing.

House lawyer Josephine Morse told McFadden that the House believes the opinion is "seriously flawed" and "conflicts with circuit precedent." She said House lawyers could file their petition for an en banc rehearing as soon as Friday, ahead of a Monday deadline set by the circuit

She said the circuit's McGahn opinion only applies to the subpoena the House Ways and Means Committee issued for the documents and not to the part of their lawsuit tied to a statute that allows lawmakers to request tax returns. However, Morse said the House lawyers need to confer more with the committee about what the next steps will be for the case.

"I'm not inclined to do this piecemeal," McFadden said, referring to whether the subpoena and statutory parts of the lawsuit should be separated. But he later acknowledged that "we very much a moving ball" at the D.C. Circuit level on whether the McGahn opinion will be upheld.

Justice Department lawyer David Morrell also suggested that the Trump administration would be fine waiting to see what the circuit does next. But he said that, if the circuit were to rule in favor of the House, the judge should stay the tax returns lawsuit pending the administration taking the McGahn case up to the Supreme Court.

"It shouldn't be the case that when they're winning, the case moves quickly, and when they're losing the case, it grinds to a halt," Morrell said.

McFadden ordered the parties to file a joint status report in a week to lay out what they think should happen next.

Experts have predicted the D.C. Circuit will rehear the McGahn case. Under circuit rules, a majority of active judges on the court who are not disqualified for the case may vote to rehear it en banc.

There are currently 11 active judges on the D.C. Circuit, seven of whom were appointed by Democratic presidents, which potentially gives the House an edge in winning an en banc rehearing.

One Trump appointee on the court, Judge Neomi Rao, may be recused from the case, as she was a lawyer during the Trump administration, whittling down the number of active Republican-appointed judges on the court to three. The panels hearing the McGahn lawsuit and another seeking Mueller grand jury materials were nearly identical, with Rao sitting for the Mueller case and Judge Karen LeCraft Henderson taking that seat for the McGahn case.

Judge Thomas Griffith wrote the majority opinion in McGahn, finding the House Judiciary Committee could not seek judicial review over the subpoenas. He wrote the interbranch dispute should instead be handled by the traditional accommodation process and other political tools, like lawmakers refusing to fund some of the president's agenda and placing holds on his nominations.

Critics of the opinion have argued it could do lasting damage to Congress's oversight powers, as Trump had promised to fight "all" the subpoenas. "By encouraging Presidential stonewalling, the court effectively dismantles the accommodation process," Judge Judith Rogers wrote in her  dissenting opinion.

The ruling may also put on ice any activity on Capitol Hill over subpoenas, specifically those likely to be challenged in court.

After the Senate voted to acquit Trump in the impeachment trial last month, speculation rose that former national security adviser John Bolton—whose attorney Charles Kupperman went to court over another House subpoena—could be subpoenaed as part of the House's continuing investigation into Trump's hold on Ukrainian military aid in exchange for investigations into the Bidens.

Andrew Wright, a former associate U.S. counsel to former President Barack Obama and current partner with K&L Gates, said the D.C. Circuit's current holding in the McGahn case may make Democrats more wary to issue any further subpoenas, including one to Bolton.

He said that, in choosing to dismiss the lawsuit on standing claims, the court ended up handing down a ruling that applied to any current or former executive branch official subject to a congressional subpoena.

McGahn had defied the subpoena at the direction of the White House, who claimed he had "absolute immunity" from testifying. Griffith's majority opinion did not reach the merits of the immunity claim.

"It's actually a broader ruling than just an absolute immunity claim," Wright said, noting the immunity theory only applied to the president's closest aides or "alter egos."

Saikrishna Prakash, a law professor at the University of Virginia who specializes in separation of powers issues, said that, in the current political landscape, the executive branch likely has more power than Congress because partisanship has made it harder to use other tools like defunding federal agencies or overturning a presidential veto.

"I do think that in the current environment, the executive has the whip hand because it has the information and Congress doesn't have the ability to squeeze the information out," Prakash said.

And he said that if the full D.C. Circuit does rehear the case, the outcome could "very well" be different, citing the Democratic majority on the bench.

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