Amazon, one of the world's largest employers, has called the National Labor Relations Board “unconstitutional.”

Amazon, a company that employs more than 1.54 million people, has claimed that the National Labor Relations Board (NLRB), the federal agency responsible for protecting workers' rights, is unconstitutional. According to The New, Amazon made that claim in a legal document filed Thursday as part of a lawsuit in which board prosecutors accused the e-commerce giant of discrimination against workers at an Amazon warehouse in Staten Island who voted to unionize had York Times.

Amazon is not the first company to question the constitutionality of the body. Last month, Elon Musk's SpaceX sued the NLRB after the agency accused the company of unlawfully firing eight employees, calling the agency “unconstitutional” in the lawsuit. Weeks later, grocery chain Trader Joe's, which accused the NLRB of union busting, declared that the NLRB's structure and organization was “unconstitutional,” Bloomberg reported. And in separate lawsuits, two Starbucks baristas independently challenged the agency's structure as they sought to dissolve their unions.

Amazon's claim is similar to existing claims from SpaceX and Trader Joe's. In the lawsuit, the company's lawyers argued that “the NLRB's structure violates the separation of powers” by “obstructing the executive authority provided for in Article II of the United States Constitution.” Additionally, Amazon claimed that the NLRB's hearings “may permit remedies beyond what is permitted without the need for a jury trial.”

Seth Goldstein, a lawyer representing unions in the Amazon and Trader Joe cases, told Portal that these challenges to the NLRB increase the chances of the matter reaching the Supreme Court. And they could lead employers to stop negotiating with unions in the hope that the courts will finally strip the federal agency of its power, Goldstein said. Amazon has a controversial history with the NLRB, which said the company violated federal labor laws last year.