The Committee on the Judiciary of the House of Representatives (plaintiff) ordered former White House counsel, Donald F. McGahn II (defendant), to testify before it. President Donald Trump told McGahn to refuse, claiming presidential advisers have absolute testimonial immunity from being compelled to testify before Congress. The Committee filed a lawsuit asking the court to enforce its subpoena. The Department of Justice (DOJ) responded on McGahn’s behalf, arguing that Article III of the Constitution prohibits federal courts from intervening to resolve disputes between the executive and legislative branches. The district court rejected McGahn’s claim of testimonial immunity and ordered him to appear before the committee. McGahn appealed.