A U.S. Department of Justice lawyer told a D.C. appeals court Thursday that an advocacy group seeking President Donald Trump's tax returns hadn't “perfected” its open records request, but at least one judge on the panel appeared skeptical.

Attorneys for the advocacy group Electronic Privacy Information Center and the DOJ sparred before the three-judge panel on the U.S. Court of Appeals for the D.C. Circuit, as part of EPIC's continued bid to force the IRS to hand over Trump's tax returns. U.S. District Judge James Boasberg of the District of Columbia tossed its Freedom of Information Act lawsuit last year, a ruling Epic appealed.

Michael Murray, a DOJ lawyer who argued on behalf of the IRS, urged the panel to keep the lower court ruling intact, insisting EPIC had not exhausted all remedies when it sought Trump's tax returns through a Freedom of Information Act request.

But Judge Patricia Millett bristled at what she described as the IRS' effort to shift the burden to EPIC in establishing its case for the release of the tax returns. When Murray stated the IRS normally requires requesters to explain their right to certain kinds of information, Millett responded that FOIA was the very source of an individual's right to agency documents. The exception, she emphasized, was if there were an exemption that applied.

If the appeals court rules in EPIC's favor, it would revive the group's lawsuit against the IRS, which could compel the agency to consider its records request. That, however, would not necessarily force the agency to hand over Trump's tax returns.

Circuit Judges Karen LeCraft Henderson and Harry Edwards also sat on the panel, where Trump's past misstatements about the IRS and his taxes fell under the spotlight. Trump has not released his tax returns to the public citing an ongoing IRS audit, a move that breaks precedent with presidents going back to Richard Nixon.

As a then-presidential candidate in 2016, Trump suggested the IRS was unfairly targeting him, and particularly his political views and religion, through those audits. As president-elect, amid public interest in any financial relationship Trump had with Russia, Trump also repeatedly denied having any financial “deal” with Russia—an assertion later clarified by Trump's tax lawyers.

Trump's words “impugn the credibility of the IRS” and the IRS “has the ability to correct that record,” John Davisson, counsel for EPIC, said Thursday.

If the appeals court rules in EPIC's favor, it would revive the group's lawsuit against the IRS, which could compel the agency to consider its records request. That, however, would not necessarily force the agency to release Trump's tax returns.

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