President Donald Trump’s administration will not comply with a Democratic request for the president’s tax returns, Treasury Secretary Steve Mnuchin announced Monday.

The administration is openly defying a federal law that says Congress can have access to any private tax information it wants. Mnuchin’s strategy is to break the law in hopes that a Republican judge will say it was unconstitutional all along.

“In reliance on the advice of the Department of Justice, I have determined that the Committee’s request lacks a legitimate legislative purpose ... the Department is therefore not authorized to disclose the requested returns and return information,” Mnuchin said in his letter to House Ways and Means Committee Chair Richard Neal (D-Mass.).

Neal had asked for six years of Trump’s personal and business tax returns last month, saying Congress needs to know more about how the IRS audits the president. The agency has audited every president annually since 1977 after a congressional investigation revealed President Richard Nixon had severely underpaid his taxes.

Many things about the situation are unprecedented. No White House has ever blocked a congressional request for tax returns, which are somewhat routine. But no committee has ever asked for a president’s tax info. And that’s probably because no president since Nixon has insisted on keeping his personal tax information a secret.

What happens next may be less unusual. Democrats have said they will probably issue a subpoena for the documents, and then sue in federal court to enforce the subpoena. That’s where the White House hopes that it can either run out the clock, as past administrations have done in subpoena battles, or eventually get a favorable ruling from the Supreme Court.

Neal said Monday he would talk to committee lawyers about his next move. Ways and Means Committee member Rep. Lloyd Doggett (D-Texas) said Democrats needed to take immediate legal action.

“We cannot allow this bad president to set bad precedent,” Doggett said. “If Trump once again faces only Republican silence and Democratic timidity, he will continue to erode our democracy by assuming more and more power.”

Trump’s tax returns are just one of several pieces of information Democrats have demanded from the Trump administration, which has adopted an unprecedented posture of defiance.

Given previous Supreme Court decisions upholding the ability of Congress to compel information from the executive branch, it would be unusual for courts to side with the White House over Trump’s taxes ― especially since a federal law explicitly says the executive is supposed to hand over the documents. But that’s why Senate Majority Leader Mitch McConnell (R-Ky.) has been cramming the judiciary with Republican judges.

Trump ally Newt Gingrich said last year that if Democrats subpoena Trump’s taxes, Republicans will need a bailout from new Supreme Court Justice Brett Kavanaugh, who was confirmed in the face of an accusation he’d sexually assaulted someone in high school.

Gingrich told The Washington Post that Democrats will “be trapped into appealing to the Supreme Court, and we’ll see whether or not the Kavanaugh fight was worth it.”

This article has been updated with a comment from Rep. Lloyd Doggett.