(CBS DETROIT) — Stellantis has filed a lawsuit against the United Auto Workers union, which is continuing to fight over its 2023 bargaining agreement and the UAW’s threat to strike.

The lawsuit, filed Thursday in the U.S. District Court Central District of California, claims that the UAW “filed sham grievances designed to justify mid-contract strikes against Stellantis that otherwise would violate [the collective bargaining agreement’s] no strike clause.” 

Stellantis claims that the union ignored the language in Letter 311, which allows the automaker to make plans for future investments with company approval and are subject to change based on consumer demand, changes in market conditions and plant performance.

The automaker is seeking a court declaration that the union “acted in bad faith” and violated the bargaining agreement.

“Ignoring this negotiated-for and mutually agreed-upon language in Letter 311, the UAW and its agents, including President Shawn Fain, have embarked on a sustained, multi-month campaign against the Company to force the planned investments without Company approval and regardless of business factors,” read the lawsuit.

This comes as the UAW announced that a supermajority of members at Stellantis’ Los Angeles Parts Distribution Center voted to request strike authorization from the International Executive Board if they cannot settle grievances. 

This is the first time Stellantis union members have held such a strike vote since multiple locals began filing grievances against the automaker, according to a news release.

“Stellantis made a contractual promise to invest in America and we are not going to let them weasel out of it,” UAW President Shawn Fain said in a statement. “Our members won those investments during the Stand Up strike, and we will strike again to make Stellantis keep the promise if we have to.”

According to an internal email obtained by CBS News Detroit, Stellantis informed workers that the company would sue the UAW.

The email also said the lawsuit “would hold both the International and the local union liable for the revenue loss and other damages resulting from lost production due to an unlawful strike.”

However, Fain has repeatedly stated that the union earned the right to strike under the 2023 agreement over alleged broken promises. Fain also said other UAW locals plan to vote on strike authorization in response to claims that the company was attempting to move production of the Dodge Durango out of the country and delaying the reopening of the Belvidere Assembly Plant in Illinois.

Stellantis cited market conditions as contributing to the delay of the Belvidere plant and proposed a consolidated Mopar Mega Hub, stamping operations in 2025 and allocating a new midsize truck in 2027, according to the lawsuit. The company also said Letter 311 included a planned future investment in the next-generation Durango in 2026 at the Detroit Assembly Complex. The plans are subject to committee approval due to “unpredictability” and “highly volatile” vehicle markets.