The National Labor Relations Board filed a complaint Thursday against Tesla, saying the company required workers to sign a nondisclosure agreement that would prevent employees from discussing working conditions and safety at the Fremont plant.

Pro-union workers have complained in the past regarding working conditions at the plant, and some pro-union employees have even violated their nondisclosure agreements to speak out against certain practices.

The labor agency’s complaint gives merit to workers’ past claims regarding safety on the production line. The claims, made by pro-union workers in mid August, fly directly in the face of Musk’s thoughts on the Model 3 production line.

“We’ve gone to great pains with the Model 3 to design it for manufacturing and to not have all sorts of bells and whistles and special features,” Musk said in May during a first-quarter earnings call. “We’ve designed it to be easy to make.”

Tesla has already responded to the NLRB’s complaint.

“As we approach Labor Day weekend, there’s a certain irony in just how far the UAW has strayed from the original mission of the American labor movement,” Tesla said in a statement. “Faced with declining membership, an overwhelming loss at a Nissan plant earlier this month, corruption charges that were recently leveled against union leaders who misused UAW funds, and failure to gain traction with our employees, it’s no surprise the union is feeling pressured to continue its publicity campaign against Tesla.”

Tesla further slammed the UAW for its role in trying to disrupt the Tesla production process, alleging that members even went as far as visiting the homes of Tesla employees.

“For seven years, the UAW has used every tool in its playbook: misleading and outright false communications, unsolicited and unwelcomed visits to the homes of our employees, attempts to discredit Tesla publicly in the media, and now another tactic that has been used in every union campaign since the beginning of time – baseless ULP filings that are meant only to generate headlines.”

The NLRB has also established a court date in November to address the charges at hand. Tesla has largely denied all allegations that call workers’ safety at the Fremont plant into question.

“These allegations, which have been filed by the same contingent of union organizers who have been so outspoken with media, are entirely without merit,” Tesla said in a statement.

Tesla CEO Elon Musk has previously made statements that the workers at the Fremont factory, which is tasked with ramping up Tesla Model 3 production, would be entering “production hell” in the coming months.

The “production hell” comes as part of Tesla’s plan to ramp up Model 3 production according to an S-Curve — a production model that requires intense investment and work early on to diffuse innovation and create the most efficient way to build a product.

Tesla and Musk have been under intense pressure to make sure the Model 3 goes off without a hitch, ensuring that a major component of Musk’s master plan — to create an affordable, high-volume EV — is within reach.