DOJ vows appeal after judge orders ex-White House counsel Don McGahn to appear before Congress

Former White House counsel Don McGahn must appear before Congress pursuant to a subpoena issued earlier this year, a Washington, D.C. federal judge ruled late Monday, in a major setback to President Trump's effort to keep aides from testifying before House impeachment investigators.

If McGahn wanted to assert executive privilege to avoid testifying, U.S. District Court Judge Ketanji Brown Jackson ruled, he would need to appear before Congress and do it himself, likely on a question-by-question basis.

It remained possible, Jackson said, that the "requested information is itself subject to withholding consistent with the law on the basis of a recognized privilege" -- but, "as far as the duty to appear is concerned, this Court holds that Executive branch officials are not absolutely immune from compulsory congressional process."

A senior Justice Department official told Fox News the department would appeal Judge Jackson's decision and seek a stay pending that appeal. Should a higher court uphold the ruling, it could set a binding precedent affecting future disputes between Congress and the White House involving executive privilege, which generally allows the president and high-level officials to refuse to answer certain questions that might impair deliberative processes or compromise presidential communications and the separation of powers.