San Francisco — The federal judge overseeing the driverless car brawl between Waymo and Uber got the fireworks started a little bit early this Independence Day week.

On Monday, U.S. District Judge William Alsup of the Northern District of California asked Uber's outside lawyers at Morrison & Foerster to explain whether they had violated court orders by failing to hand over Waymo computer files in the firm's possession.

Last month, Waymo asked that Uber's attorneys be held in contempt for failing to disclose they had access to a portion of the 14,000 files allegedly stolen by former Waymo engineer Anthony Levandowski that sit at the heart of the dispute. Uber claims it never received or used any of the files in its own driverless car technology. But Waymo's lawyers at Quinn Emanuel Urquhart & Sullivan claim that Morrison & Foerster lawyers had access to some of the files as part of due diligence conducted prior to Uber's purchase of Levandowski's driverless car startup.