Uber employee Anthony Levandowski is at the center of the ride-sharing service’s current legal battle with competitor Waymo. But now, Levandowski has another potential adversary against him: his own company. Uber said in a letter to Levandowski that if he did not follow the court’s orders, the company could take action that could include firing him, the New York Times reports.

Via TechCrunch, the letter, which was sent May 15, requested that Levandowski either confirm he never took documents from Waymo or that he hand over any documents within his possession. Levandowski, who is not directly being sued, has so far claimed his Fifth Amendment rights against self-incrimination during the case.

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Below is an excerpt from the letter:

[A]s you know, your employment at Uber is on an at-will basis. See A. Levandowski Employment Agreement, Aug. 17, 2016 ¶ 5(a) (“August 17, 2016 Employment Agreement”). As a condition of your employment at Uber, you must comply with all of the requirements set forth in this letter. If you do not agree to comply with all of the requirements set forth herein, or if you fail to comply in a material manner, then Uber will take adverse employment action against you, which may include termination of your employment and such termination would be for Cause.

If you comply with these requirements, your employment at Uber will continue on an at- will basis. For the avoidance of doubt, Uber retains the sole right to determine whether you are in compliance with the requirements set forth above.

The move is the latest turn in a winding case involving Uber, Levandowski and Waymo, which is owned by Google parent company Alphabet. Levandowski previously worked as a Google engineer before leaving to form self-driving truck startup Otto last year and Otto was then purchased by Uber. However, Waymo accused Uber of working with Levandowski to steal confidential documents relating to Waymo’s self-driving car efforts and brought a case against the company earlier this year.

While Uber earlier conceded that Levandowski took Waymo documents, the company has steadfastly denied that any information from the documents was used in its self-driving car development. Levandowski has also made several recent concessions in light of the case, including stepping away from Uber’s work on LiDAR implementations, which plays a central role in self-driving technology.

Read: DOJ Investigating Uber Over Greyballing Issue

For many tech companies, self-driving car technology has been a major point of emphasis. Companies ranging from Apple to Lyft have all invested significant resources into research and development for their own autonomous technology, in hopes of getting to market first.