The case arose from a political dispute between President Obama and Senate Republicans, who claimed he had no authority to put three people on the National Labor Relations Board in January 2012 when the Senate was out of town.
He used a president's power, granted by the Constitution, to "fill up all vacancies that may happen during the recess of the Senate." But the Republicans said the Senate was not in recess at the time the appointments were made, because every three days a senator went into the chamber, gaveled it to order, and then immediately called a recess.
By a unanimous vote, the Supreme Court agreed that the Senate was not in recess, holding that it's up to both houses of Congress to define when they're in session or in recess. As a result of the decision, the Senate can frustrate a president's ability to make recess appointments simply by holding periodic pro forma sessions, a tactic used in recent years by both political parties.
Read more: http://www.nbcnews.com/politics/supreme-court/supreme-court-narrows-presidents-recess-appointment-power-n141601