The Supreme Court on Monday is set to hear a bitter dispute between Republicans and the White House over whether President Obama exceeded his authority when appointing members to the National Labor Relations Board during a congressional recess.

The justices' decision could cast a legal cloud over hundreds of rulings by the board, which resolves complaints of unfair labor practices and conducts elections for labor union representation.

The case, NLRB v. Noel Canning, centers around recess appointments Obama made to the labor board. In January 2012, Obama appointed three members to the board when the Senate was on break. Presidents can circumvent required Senate approval if the chamber is on recess, a move Obama deemed necessary because of repeated GOP blocks of his nominations to the panel.

Republicans worried the Obama appointees had a pro-union bias. But the White House said the GOP block was done solely for political reasons.

Then in February 2012 the NLRB ruled against Noel Canning (part of Noel Corp.), of Yakima, Wash., in a dispute with the Teamsters union. The company, aided by the U.S. Chamber of Commerce, challenged the decision, arguing that the president's January appointments to the NLRB were invalid and thus the board didn't have the necessary quorum to resolve its dispute.

The U.S. Court of Appeals for the D.C. Circuit ruled in favor of Canning, saying Obama violated the law when he bypassed the Senate. The court said recess appointments are constitutional only if the vacancies and appointments occur in between official sessions of Congress.

The NLRB appealed, and the Supreme Court took up the case.

If the high court rules against the labor board, a minimum of 100 NRLB decisions -- and possibly more -- made by the recess-appointed members could be deemed invalid.

The labor board also would effectively be shut down, as a ruling against the Obama administration would leave the five-member board with only one member, and it needs three to conduct business.

Supporters of Obama's action say presidents of both parties routinely make recess appointments to install officials who otherwise would have had a hard time winning Senate confirmation.

"The recess appointment power has played an important role in our nation's history by helping keep the government running smoothly when the Senate was unable to provide its advice and consent on nominations, for reasons ranging from lengthy holidays to minority obstruction through the filibuster," said a report by the Brennan Center for Justice at the New York University Law School.

The Brennan Center report added that if the Supreme Court upholds the lower court's ruling, "the loss of this important tool would profoundly alter the balance of power between the president and the Senate."

But others argue the Obama appointments were unconstitutional because Senate Republicans at the time officially kept the chamber open by holding "pro forma" sessions -- a procedure in which lawmakers understand that no business will be transacted except by unanimous consent.

"If recess appointments can be made during short 'recesses' then they [should] terminate at the end of the next short 'session' -- and not the full two-year period," said Michael McConnell, Stanford Law School professor, in an analysis of the case for the Washington Legal Foundation.

Recent changes in the Senate's filibuster rules mean that most presidential nominations now only need a simple majority to clear procedural hurdles and head toward a final simple majority passage in the 100-member chamber, not the 60 votes previously required to block a nominee.