• The National Labor Relations Board authorized a new union election at one of Amazon's Alabama warehouses, the labor union behind the effort said Monday.
• Amazon employees at the Bessemer, Alabama, warehouse, known as BHM1, in April overwhelmingly voted against joining the Retail, Wholesale and Department Store Union.
• The union argued Amazon illegally interfered in the election, kicking off a protracted legal battle, which resulted in the NLRB ruling in the RWDSU's favor.
• A new election date has yet to be announced.

The National Labor Relations Board authorized a new union election at one of Amazon's Alabama warehouses, the labor union behind the effort said Monday.

In a statement, the Retail, Wholesale and Department Store Union said an NLRB director formally granted a new union election at Amazon's Bessemer, Alabama warehouse. As a result, workers at the facility, known as BHM1, will get another chance to vote on whether to join the RWDSU.

NLRB spokesperson Kayla Blado confirmed the agency has ordered a new election, but didn't specify when the new union election will take place.

BHM1 was the site of a high-stakes union drive that attracted global attention, including from President Joe Biden. In April, employees overwhelmingly rejected forming a union, with fewer than 30% of the votes tallied in favor of joining the RWDSU.

The RWDSU sought to challenge the results, arguing Amazon illegally interfered in the election. It kicked off a protracted legal battle with months of hearings examining the lead up to the vote. Much of the debate centered around Amazon's decision to install a mailbox on site at the facility, which the RWDSU argued created the false appearance that Amazon was conducting the election and intimidated workers into voting against the union.

In August, a NLRB hearing officer recommended the election results be set aside and that another vote should take place. At the time, Amazon said it would appeal the decision.

Region 10 Director Lisa Henderson, based in Atlanta, issued the decision and directions for a second election at BHM1 on Monday.

After reviewing the evidence and arguments at hand in the case, Henderson wrote in her decision, "I agree with the hearing officer's recommendations. Accordingly, I affirm the hearing officer's rulings, I adopt her recommendation to sustain certain objections, and I order a second election."

Amazon spokesperson Kelly Nantel told CNBC in a statement that the company disagrees with the NLRB's decision Monday and that Amazon doesn't think unions are the best answer for its employees.

"Our employees have always had the choice of whether or not to join a union, and they overwhelmingly chose not to join the RWDSU earlier this year," Nantel said. "It's disappointing that the NLRB has now decided that those votes shouldn't count."

Union President Stuart Appelbaum said in a statement: "Today's decision confirms what we were saying all along – that Amazon's intimidation and interference prevented workers from having a fair say in whether they wanted a union in their workplace – and as the Regional Director has indicated, that is both unacceptable and illegal. Amazon workers deserve to have a voice at work, which can only come from a union."

Labor unions have organized some of Amazon's European workforce, but no U.S. facility has successfully formed or joined a union.

Since the Bessemer election, there has been an uptick of labor activity within Amazon's warehouse and delivery workforce. In October, a group of Amazon employees on Staten Island filed for a union election with the NLRB, before rescinding their application after the agency determined they needed to gather more signatures.

Amazon workers at a Canadian warehouse in September filed for a union election with the backing of a local chapter of the International Brotherhood of Teamsters.

The Teamsters, one of the largest labor unions in the country, has made it a priority to unionize Amazon workers. The union in June authorized a sweeping plan to organize Amazon workers. Teamsters representatives have also shown up at government meetings in pockets across the U.S. in an effort to thwart local warehouse projects and to prevent what it argues are low-quality jobs.