A letter written by a former Uber Technologies Inc. employee to an in-house lawyer has thrown a wrench into the company's blockbuster trade secrets battle with autonomous car rival Waymo.

During a pretrial conference Tuesday morning in San Francisco, Uber's former manager of global intelligence Richard Jacobs testified that Uber used encrypted messaging services and other techniques to keep intelligence on other companies off its server, where it could be found during litigation, and that he had informed in-house counsel at the ride-hailing company in a letter after he left the company about what he saw as ethically problematic practices.

U.S. District Judge William Alsup of the Northern District of California, who is presiding over the case, noted that the techniques could have been used by Uber to skirt its obligation to hand over information to Waymo and he delayed the trial, which was due to begin next week.