The federal judge overseeing a trade secret dispute between Uber and the Google spin-off Waymo has recommended that federal prosecutors begin a criminal investigation into the alleged theft of Waymo’s self-driving car technology.

Judge William Alsup’s referral of the case to the US attorney came amid a flurry of orders in the contentious lawsuit between two Silicon Valley giants. Alsup also denied Uber’s attempt to force the case into arbitration and partially granted Waymo’s request for a preliminary injunction against Uber.

The details of the preliminary injunction are sealed, so it is unclear to what extent Uber will be affected by the order. Waymo had sought to compel the return of its documents and to bar Uber from using lidar technology it said was stolen.

Waymo, which is owned by Google parent company Alphabet, sued Uber in February, alleging that the ride-sharing company had orchestrated the “calculated theft” of its lidar technology. Waymo’s case centered around Anthony Levandowski, a longtime Google employee who left to start his own self-driving trucking company, Otto, in 2016.

Uber purchased Otto and installed Levandowski as the head of its self-driving car program, which Uber CEO Travis Kalanick has said is “existential” to the company’s future.

Waymo alleged that Levandowski downloaded 14,000 documents from Waymo servers prior to leaving the company and has used them to help Uber kickstart its own program.

Uber has denied using Waymo technology, but the case has been complicated by Levandowski’s invocation of his fifth amendment right against self-incrimination. Levandowski has refused to answer questions about the alleged document theft or submit his personal computer for a search for the documents.

Alsup referenced the difficulty this has created for the case in his order denying arbitration, writing: “Levandowski’s assertion of his fifth amendment privilege has obstructed and continues to obstruct both discovery and defendants’ ability to construct a complete narrative as to the fate of Waymo’s purloined files.”

Waymo called the attempt to move to arbitration, which takes place behind closed doors, a “desperate bid by Uber to avoid the court’s jurisdiction”, adding: “We welcome the court’s decision today, and we look forward to holding Uber responsible in court for its misconduct.”

“It is unfortunate that Waymo will be permitted to avoid abiding by the arbitration promise it requires its employees to make,” a spokesperson for Uber said in a statement. “We remain confident in our case and welcome the chance to talk about our independently developed technology in any forum.”

Uber declined to comment on the referral to the US attorney.

In court hearings, Alsup has commented on the strength of the evidence that Levandowski downloaded the documents, saying at one point: “I’ve never seen a record this strong in 42 years.”

In his referral of the case to the US attorney “for investigation of possible theft of trade secrets based on the evidentiary record supplied thus far”, Alsup wrote that he “takes no position on whether a prosecution is or is not warranted, a decision entirely up to the United States Attorney”.

Brian Horne, an intellectual property attorney at Knobbe Martens, said that referrals for criminal prosecution in trade secret cases were “not very common”. Prior to 2016 any prosecution would have likely occurred under state laws, he said, but the Defend Trade Secrets Act of 2016 allows for federal prosecution.

Violation of the DTSA can carry up to a 10-year prison term.

“Certainly if you’re a defendant and your case gets sent to the US attorney, that’s probably not a good sign,” Horne said. “I don’t think you want to be in that position.”