A major separation-of-powers decision by the U.S. Supreme Court on Thursday may prevent President Barack Obama from making recess appointments for the rest of his tenure, and will trigger uncertainty for months or years to come at the National Labor Relations Board.

Ruling in National Labor Relations Board v. Noel Canning, the court invalidated three recess appointments Obama made to the board during a brief Senate recess in January 2012. The three-day recess, the court agreed, was too short to trigger the president’s power under the Constitution to “fill up all Vacancies that may happen during the Recess of the Senate.”