The president’s personal attorneys also asked U.S. District Judge Trevor N. McFadden to dismiss the case.

In the filing, Justice Department attorneys argue that the Democratic-controlled House Ways and Means Committee is improperly enlisting the judiciary in a fight between Congress and the White House over the tax returns.

“For nearly two hundred years, the Legislative Branch never invoked the power of the Judiciary to decide which side should win in a political battle with the Executive,” it states.

A 1924 law explicitly gives the chair of the House tax-writing panel authority to receive the documents.

Rep. Richard E. Neal (D-Mass.), chairman of the House Ways and Means Committee, filed a lawsuit earlier this year against the Internal Revenue Service and the Treasury Department seeking six years of the president’s personal and business returns.

Neal previously argued in a court filing: “In refusing to comply with the statute, Defendants have mounted an extraordinary attack on the authority of Congress to obtain information needed to conduct oversight of Treasury, the IRS, and the tax laws on behalf of the American people who participate in the Nation’s voluntary tax system.”

The attorneys in Trump’s Justice Department offer a number of arguments for denying Neal’s request, but their main case is dismissing Congress’s oversight role under Article I of the Constitution, said Steve Rosenthal, an expert at the Urban-Brookings Tax Policy Center, a nonpartisan think tank. The Justice Department filing argues that the House panel has “no institutional interest in confidential tax information.”

“It’s an exaltation of the executive branch over the legislative branch that goes to the heart of our checks and balances,” Rosenthal said. “The Justice Department’s position is extreme. If this position was accepted, I can’t see any congressional investigation of the executive branch moving forward.”

The prolonged court case has increased the odds that Trump will go into his reelection campaign without releasing his returns. The leading Democratic presidential candidates have released their tax returns.

Trump repeatedly promised during his 2016 presidential campaign to release his returns, though he said he could not do so at the time because he was under audit.