According to the DOJ, the committee — chaired by Rep. Jerry Nadler (D-N.Y.) — has "come nowhere close to demonstrating a particularized need" for the grand jury material.
In fact, the DOJ argued that conflicting language from Democratic leaders undermine their central claim for needing the secret files, citing statements from House Speaker Nancy Pelosi (D-Calif.) and House Majority Leader Steny Hoyer (D-N.Y.).
"Most prominently, the Speaker of the House has been emphatic that the investigation is not a true impeachment proceeding," the DOJ wrote.
"And the House Majority Leader had even explained that branding the Committee's proceeding as 'impeachment' is a simply a device to enhance the Committee's legal arguments in this and other courts," the agency explained.
The DOJ went on to say:
As the Committee's Chairman has stressed—and as the Speaker of the House and the House Majority Leader both reiterated this week—the purpose of its investigation is to assess numerous possible remedial measures, including censure, articles of impeachment, legislation, Constitutional amendments, and more.
What may come of this investigation—if anything—remains unknown and unpredictable.
Because congressional impeachment proceedings "are not 'judicial proceedings' under the plain and ordinary meaning of that term," the DOJ said secrecy rules governing federal grand juries must be upheld.