House Democrats have launched an investigation into whether President Donald Trump made false statements in his written answers to special counsel Robert Mueller as part of his probe into now-debunked allegations of criminal conspiracy between the 2016 Trump campaign and Russia, according to CNN.

“Did the President lie? Was the President not truthful in his responses to the Mueller investigation?” House Judiciary Committee general counsel Douglas Letter asked before the U.S. Court of Appeals for the District of Columbia Circuit on why lawmakers require access to grand jury material obtained by Mueller.

On Monday, a federal appeals panel is voicing skepticism over the Justice Department’s claim it can defy Congress’ request for secret material from the Mueller report.

Two of the three judges who heard arguments at a hearing seemed prepared to order at least some of the material sought by the House for its impeachment inquiry to be turned over.

The House Judiciary panel is seeking grand jury testimony and other details redacted from the public version of Mueller’s investigation.

Last month, a judge ordered the Justice Department to turn over the redacted material, but the Trump administration appealed.

In the court filings, the Justice Department argued that once the grand jury material is released to the House Judiciary Committee, there is no guarantee that it will remain secret “and the confidentiality of the grand jury information will be lost for all time.”

“In order to reach the decision it did, the Court resolved difficult disputes between co-equal branches of government, including the question of what suffices to initiate the impeachment of a President,” wrote Department of Justice attornies. “The public interest lies in maintaining the status quo until an appellate court has had time to review and resolve these substantial legal question.”

The Associated Press contributed to this report.