Trump appointed Whitaker, who was chief of staff to former Attorney General Jeff Sessions, in November. In making the appointment, Trump passed over Deputy Attorney General Rod Rosenstein. Opponents of the move argued Whitaker was unqualified for the position, and not confirmed by the Senate.
The challenge argues that Rosenstein automatically should've become attorney general when Sessions stepped down, and that Whitaker's appointment violated the Appointments Clause of the Constitution. It also contended that Rosenstein's name, and not that of Whitaker, should be listed on the case.
The refusal of the court to rule indicates there will be no future court challenge of any of his rulings as acting attorney general.
Attorneys argued that "If this court declines to resolve this question immediately and instead determines several months in the future that Mr. Whitaker's appointment was always invalid, then 'unwinding' all of those personal orders would be a fraught and disruptive exercise that could embroil the federal courts in innumerable collateral disputes."
A similar case in Maryland federal court is still pending.
Monday, the high court also declined to hear a challenge to the broad powers of the Consumer Financial Protection Bureau. It argues the agency violates the constitutional separation of powers. Justices also refused to hear a case involving Montana's campaign finance laws -- which was brought by a man who said the state's contribution limits, among the lowest in the United States, are unconstitutional under the First Amendment.