The ruling Thursday by the 3rd U.S. Circuit Court of Appeals in Philadelphia came on the same day that a Senate panel considered a slate of five nominees for full terms on the labor board. Senate Republicans said they would oppose two of the nominees -- Sharon Block and Richard Griffin -- because they currently sit on the board as recess appointments.
In its 2-1 decision ruling, the appeals court said that under the Constitution recess appointments can be made only between sessions of the Senate, not any time the Senate is away on a break.
The court's action mirrors a far-reaching ruling by the U.S. Court of Appeals in Washington, D.C., earlier this year.
The Obama administration has appealed that ruling to the Supreme Court, arguing that such an interpretation would invalidate hundreds of recess appointments made by presidents over more than 100 years.
The latest ruling says Obama had no constitutional authority to install attorney Craig Becker to the labor board in 2010 while the Senate was adjourned for two weeks.
The White House did not immediately respond to a request for comment.
More than a hundred companies have appealed NLRB decisions this year arguing that the board does not have enough validly appointed members to conduct business.