The Justice Department’s Office of Legal Counsel released a new legal opinion stating that subpoenas from House Democrats in their impeachment investigation into President Trump will be considered “legally invalid” if Trump administration witnesses aren’t allowed to have an attorney with them while testifying.

The new legal stance by the Trump DOJ is detailed in a five-page legal memo dated Nov. 1, just one day after the House of Representatives voted to formalize the opening of its impeachment process stemming from a Ukraine whistleblower in a near-party-line vote. Republicans had previously complained about the closed-door nature of the impeachment proceedings as well as the lack of a launch vote, but the new legal justification by DOJ could escalate the battle over the Trump administration’s lack of cooperation with the House, as the Trump administration continues to slow-walk some information requests and stonewall some subpoenas.

“Congressional committees participating in an impeachment inquiry may not validly compel executive branch witnesses to testify about matters that potentially involve information protected by executive privilege without the assistance of agency counsel,” Assistant Attorney General Steven Engel wrote. “Congressional subpoenas that purport to require executive branch witnesses to appear without agency counsel in these circumstances are legally invalid and are not subject to civil or criminal enforcement.”

DOJ also said that, in addition to fighting new subpoenas that don’t allow witnesses to have a lawyer at their side, they would continue to fight subpoenas issued in September and October, noting that before the Oct. 31 vote, the House “had not vested any committee in the current Congress with the authority to issue subpoenas in connection with an impeachment inquiry. As a result, subpoenas issued before that date purporting to be ‘pursuant to’ an impeachment inquiry were not properly authorized.”

A court battle over the Trump administration’s subpoena obligations was expedited on Monday, with Judge Richard Leon of D.C.’s District Court ordering final arguments over former Trump deputy national security adviser Charles Kupperman’s possible testimony to be made by Dec. 10. Kupperman asked the court to resolve the legal dispute between the House, which issued a subpoena for his testimony, and the White House, which ordered him not to appear.

White House counsel Pat Cipollone said that current or former senior officials in the Trump administration may be “absolutely immune from compelled congressional testimony with respect to matters related to his service as a senior adviser to the President.”

