Amazon is obligated to collectively bargain with warehouse workers at its San Francisco distribution facility, the U.S. federal labor board says.

A complaint issued Monday by a regional director of the National Labor Relations Board accused Amazon of illegally refusing to negotiate with employees after a majority signed union authorization cards in the fall.

The complaint relies on a precedent set by the NLRB during the Biden administration. A 2023 decision found that if a union gains a majority of support in the workplace, an employer has the choice to voluntarily recognize the union, or it must challenge the action and file a petition with the labor board to hold a formal election.

Amazon did not file any such petition, according to the complaint.

The complaint sets the stage for bargaining orders “at many other locations where Amazon has dodged its legal obligation to negotiate with the union,” the Teamsters said in a statement Monday.

Workers at Southern California warehouses DAX5 in City of Industry and DAX8 in Palmdale, as well as other warehouses in New York City, Atlanta and Skokie, Ill., have sought union recognition from the company.

“It’s clear workers continue to win when they fight,” Randy Korgan, director of the Teamsters Amazon division, said in a statement.

Amazon disputed the claims.

“This complaint is predicated on a baseless legal theory which undermines employee rights, disregards decades of NLRB practice, and ignores Supreme Court precedent. It is completely without merit and we look forward to establishing that through the legal process,” Amazon spokesperson Eileen Hards said in an email.

The complaint is an early step by the NLRB in litigating its case, which will be reviewed by an administrative law judge at a hearing scheduled for Aug. 5. The judge’s decision on whether Amazon should be ordered to bargain with workers could then be appealed to the labor board in Washington and then in federal court.

The case likely faces an uphill battle with the labor board now under the control of the Trump administration.

In January, Trump fired NLRB board member Gwynne Wilcox, leaving the board with only two members — one a Republican and the other a Democrat.

After firing general counsel Jennifer Abruzzo, the Trump administration appointed William Cowen in February as acting general counsel. Cowen has already rescinded a series of more worker-friendly guidelines and interpretations that had been issued by his predecessor.

Another similar case regarding Amazon’s obligation to bargain with warehouse workers is tied up in the courts. Workers at Amazon’s Staten Island, N.Y., warehouse voted to unionize in 2022, but the company has not bargained with workers. The NLRB issued a complaint in 2023, but proceedings were put on hold after Amazon filed a lawsuit arguing the NLRB’s structure is unconstitutional, spearheading an effort with SpaceX, whose chief executive is White House advisor Elon Musk, to reshape or dismantle the labor agency.

The Teamsters have criticized Trump’s nominee for the NLRB’s permanent general counsel, Crystal Carey, a partner at the law firm Morgan Lewis.