Federal judge William Alsup delayed the upcoming trial between Uber and Waymo because the ride-hailing company withheld key evidence during the discovery process. Waymo, the self-driving car company that was spun out of Google, sued Uber in February for allegedly stealing key parts of its autonomous vehicle technology.

The evidence in question is a 37-page memo from ex-Uber security analyst Ric Jacobs that was written to the company’s legal team. The letter states that Uber’s “Marketplace Analytics” team existed for the sole purpose of “acquiring trade secrets, code base,” and other intelligence from competitors including Waymo, according to Gizmodo. The letter also describes concern over clandestine practices performed by Uber, such as using “non-attributable” devices and self-destructing chat apps like Wickr that helped hide communications about these practices. (Uber was previously found to be using Wickr when it was caught investigating its legal foes in 2016.)

Jacobs, who was fired by Uber in April, took the stand at a hearing Tuesday in San Francisco to answer questions about the letter. He contradicted some of the claims made in it, including the specific mention of knowledge of stealing from Waymo. Jacobs’ disagreements reportedly come from the fact that he didn’t fully read the letter before his legal team sent it.

Jacobs says he didn’t read the whole letter before his own lawyers sent it

He added that he reached a settlement with Uber after his firing, and that he has agreed not to disparage the company in the press or public. But Jacobs made other claims during his time on the stand that could damage Uber’s defense in the Waymo lawsuit.

The suit centers around the alleged theft of thousands of documents by former Google self-driving engineer Anthony Levandowski. Shortly after Levandowski left Google, he founded Otto, a self-driving truck startup. Otto was eventually acquired by Uber. Waymo’s lawyers have argued that Uber wound up with those allegedly stolen files and merely masqueraded the process as an acquisition.

Jacobs testified that Uber established these shadow communications channels and practices in order to protect the company from potential litigation. He also testified that Ed Russo, who works for Uber’s Strategic Services Group, bragged about using these communication methods to set up secret meetings between CEOs of a “big” and “small” company around this time. He also testified that this Strategic Services Group had two "off the books" employees working on the company’s self-driving car unit.

The letter from Jacobs was reportedly shared with Alsup last week by the US Department of Justice. It was apparently collected by the US attorneys’ office earlier this year as part of one of the many ongoing criminal investigations into Uber’s business practices. Waymo asked Alsup Monday to delay the case in light of the letter’s surfacing, and argued that Uber intentionally withheld and destroyed evidence related to the letter.

The in-house counsel that Jacobs’ letter was addressed to, Angela Padilla, testified Tuesday that the company had used approved search terms to search for any documents related to the trial. She had previously testified that the company looked “everywhere” for evidence to include in the discovery process.

“I can no longer trust the words of the lawyers for Uber in this case,” Alsup said at today’s hearing. “We’re going to have to put the trial off because if even half of what’s in that letter is true it would be a huge injustice to force Waymo to go to trial.”

“We have to get more to the bottom of this shadow system Uber set up,” Alsup reportedly added. It’s clear, he said, that the “real stuff goes on the shadow system.”

The trial was slated for December 4th, but no new date has been set. The jury duty process has been canceled for now.