Setting the stage for a major constitutional showdown over the scope of presidential power, the U.S. Supreme Court agreed this morning to hear the case of National Labor Relations Board v. Noel Canning. At issue is whether President Barack Obama’s three purported recess appointments to the NLRB in January 2012 violated the Constitution because they occurred when the Senate was not actually in recess.

Under the Appointments Clause of the U.S. Constitution, the president may make temporary appointments to "fill up all vacancies that may happen during the recess of the Senate, by granting commissions which shall expire at the end of their next session." In this instance, however, Senate Republicans were holding pro forma sessions—convening every three days—for the purpose of denying the president his lawful ability to invoke the recess appointment power.

But Obama ignored this impediment and still made the appointments. That unilateral action earned the president an unwelcome rebuke from the U.S Court of Appeals for the District of Columbia Circuit, which ruled the appointments unconstitutional and upbraided the White House for adopting a position that “would demolish the checks and balances inherent in the advice-and-consent requirement, giving the President free rein to appoint his desired nominees at any time he pleases, whether that time be a weekend, lunch, or even when the Senate is in session and he is merely displeased with its inaction.” Moreover, the D.C. Circuit held that the recess appointment power may never be used during an intra-session Senate break and that it may only be invoked when the vacancy at issue originally arose during a recess.

That decision is now before the U.S. Supreme Court. Oral argument is expected later this fall.