Amazon.com (NASDAQ:AMZN) has joined SpaceX and Trader Joe’s in asserting that the National Labor Relations Board’s (NLRB) in-house enforcement proceedings violate the U.S. Constitution. The retail giant, facing numerous cases alleging interference with workers’ right to organize, filed a complaint with the NLRB, stating its intention to argue that the agency’s structure infringes on its right to a jury trial.

Amazon contends that the limits on the removal of administrative judges and the board’s five members, appointed by the president, are unconstitutional. This filing is part of an ongoing case accusing Amazon of unlawfully retaliating against workers at a Staten Island warehouse where employees voted to unionize in 2022. Amazon, confronting over 250 NLRB complaints related to alleged labor violations nationwide, denies any wrongdoing.

SpaceX and Trader Joe’s have also raised similar arguments, with SpaceX filing a lawsuit last month after the NLRB accused the company of firing engineers critical of CEO Elon Musk. Trader Joe’s presented these claims in January during an NLRB case hearing, and two Starbucks (NASDAQ:SBUX) baristas seeking to dissolve their unions have challenged the board’s structure in separate lawsuits.

The NLRB has not commented on the matter. The agency’s general counsel issues complaints against employers for alleged violations of federal labor law. These cases go through administrative judges before reaching the five-member board, whose decisions can be appealed in federal court.

The increasing challenges to the NLRB raise the likelihood of the issue reaching the U.S. Supreme Court. The conservative majority in the Supreme Court has shown skepticism towards in-house proceedings of other U.S. agencies. Seth Goldstein, a lawyer representing unions in the Amazon and Trader Joe’s cases, suggests that these pending cases might encourage other employers to resist bargaining with unions, anticipating that courts may curtail the NLRB’s enforcement powers.