SAN FRANCISCO, Nov 3 (Reuters) - A federal judge in San Francisco made it more difficult for Alphabet Inc's Waymo unit to prove it suffered financially from the alleged theft of autonomous car trade secrets by Uber Technologies Inc, ruling to exclude testimony from Waymo's damages expert.
Waymo has estimated damages in the case at about $1.9 billion, according to court filings. Uber has denied using any of Waymo's trade secrets and rejects the financial damages claim.
Uber and Waymo are competing to develop autonomous car technology. A Waymo attorney said previously the goal of the case was "to stop Uber from using its trade secrets."
The chief of Uber's self-driving car program has left the company because of the lawsuit, for instance.
U.S. District Court Judge William Alsup late on Thursday issued an order excluding Waymo's expert, Michael Wagner, from the case and restricting use of financial evidence at trial and denying other relief, according to a docket entry.
The docket summarizes the decision, but the details are under seal until later on Friday.
University of Florida law professor Elizabeth Rowe said it was a setback to not be able to put the damages expert on the stand, but that it was not yet clear how broad the ruling was.
"It might affect their ability to show - to prove - the high monetary damages using their own expert," she said, adding there are ways to get the information in, if the scope of the exclusion is limited to the one person.
Uber described rulings on the expert, the exclusion of a potential defendant related to Uber's former self-driving car chief and others as signs of success.
"Waymo's case continues to shrink," the ride-services company, which is developing its own autonomous car technology, said in a statement.
Waymo did not immediately respond to a request for comment on the damages expert decision.
Alsup recently agreed to Waymo's request to delay a trial to decide the dispute from October to early December, citing the need to investigate evidence Uber had not disclosed earlier.
Waymo sued Uber in February, claiming that Anthony Levandowski, the former head of Uber's self-driving effort who Waymo alleges downloaded more than 14,000 confidential files before leaving Waymo to set up a self-driving truck startup company that Uber then acquired.
Waymo in settlement talks had sought at least $1 billion from Uber, which rejected that and other terms as non-starters, sources previously told Reuters.
Waymo views winning a permanent injunction against Uber using any Waymo intellectual property as the main priority, another source familiar with the company's thinking said.
Reporting by Peter Henderson, editing by G Crosse