An American judge has denied Google’s self-driving car offshoot Waymo access to details of how Uber hunted for allegedly stolen documents handed to it by former Waymo employee Anthony Levandowski.

The attempt to secure discovery came as part of the long-running American court battle between Waymo – owned by Google daddy Alphabet Inc – and controversial taxi app Uber.

In spite of Waymo’s insistence that evidence was being withheld, Judge Jacqueline Scott Corley, sitting in the US District Court for Northern California, ruled:

“Waymo’s insistence that it is entitled to all privileged communications regarding Uber’s efforts to get Mr Levandowski to return Waymo’s files is unpersuasive and unsupported by citation to any authority.”

Legal news website Law360 reported [paywalled] that some disclosure from Uber had been ordered by the judge, relating to two letters. One was from Uber to Levandowski, banning him from working on LIDAR sensor tech, while the other formally notified him that he had been sacked by Uber.

Waymo is suing Uber for theft of trade secrets. A former Google/Waymo employee, Levandowski left the self-driving car unit to set up his own autonomous vehicle company, Ottomotto, which was bought by Uber for $680m. He allegedly took more than 14,000 documents with him when he quit Waymo, which at the time was still an integral part of Google rather than a standalone venture.

Though he is not named as a defendant, Levandowski has pleaded the 5th Amendment and refused to testify. He has since been fired from Uber after not producing various documents that the parties alleged he held. A judge in an earlier hearing declared:

“If Uber were to threaten Levandowski with termination for noncompliance, that threat would be backed up by only Uber’s power as a private employer, and Levandowski would remain free to forfeit his private employment to preserve his Fifth Amendment privilege.” ®