Tesla is being accused of taking steps to keep employees in Buffalo, New York, from unionizing, according to a complaint from the National Labor Relations Board.

On Tuesday, the NLRB’s regional director for Buffalo, Linda Leslie, filed the complaint. In it, she said Tesla “promulgated and maintained,” an acceptable use policy for workplace technology in 2023 that was meant to “discourage its employees from forming, joining, or assisting the Union or engaging in other concerted activities,” after allegations were raised by members of Workers United.

CNBC obtained a copy of the complaint through a Freedom of Information Act request.

The policy restricted Tesla workers from “recording, unauthorized solicitating [sic] or promoting,” and “creating channels and distribution lists,” among other things, the complaint said.

The NLRB also claims the policy had the effect of “interfering with, restraining, and coercing employees in the exercise of rights guaranteed” under the National Labor Relations Act, which generally protects workers’ rights to discuss organizing, join a union and collectively negotiate for better pay and working conditions.

The Tesla Buffalo plant was supposed to manufacture solar panels, but has been used more recently to assemble electric vehicle charging equipment, and to house a team of AI software data labelers.

Last month, the Buffalo plant was home to a number of job cuts put in place as part of a broader restructuring at the electric vehicle company. According to a WARN notice filed in the state, Tesla is laying off 285 employees in the state of New York, mostly at the Buffalo factory. The company is eliminating thousands of jobs worldwide after declining EV sales in the first quarter.

Tesla and CEO Elon Musk have clashed with union proponents for years and were found to have engaged in union busting. In 2021, the NLRB decided that Tesla violated labor laws when it fired a union activist, and when Musk wrote on Twitter in 2018: “Nothing stopping Tesla team at our car plant from voting union. Could do so tmrw if they wanted. But why pay union dues & give up stock options for nothing?”

An administrative court ordered the CEO to remove the post. Tesla challenged the order but its petition for review was denied. The post in question remains on Musk’s X account, where he has 182.7 million listed followers.

Tesla has also faced workers’ rights challenges in Europe. Last year, Swedish service technicians began a strike that continues today, with the labor group allowing for some authorized work to take place at times. The employees in Sweden, where a majority of the workplace is involved in unions, are seeking a collective bargaining agreement with Tesla.

Tesla didn’t immediately respond to a request for comment.

Read the complaint here: