The U.S. Supreme Court sided on Thursday with Starbucks, in the coffee chain's challenge to a judicial order to rehire seven Memphis employees fired as they sought to unionize in a ruling that could make it harder for courts to quickly halt labor practices contested as unfair under federal law.

The justices threw out a lower court's approval of an injunction sought by the U.S. National Labor Relations Board (NLRB) ordering Starbucks to reinstate the workers while the agency's in-house administrative case against the Seattle-based company proceeds.

Hundreds of complaints have been filed with the NLRB accusing Starbucks of unlawful labor practices such as firing union supporters, spying on workers and closing stores during labor campaigns. Starbucks has denied wrongdoing and said it respects the right of workers to choose whether to unionize.