Attempting to dial back what a federal judge called “pretty convincingearly signs about claims that Uber stole self-driving-car technology from Google spinoff Waymo, Uber on Friday unleashed what it hoped was a killer retort.

The ride-hailing giant said it couldn’t have used a stolen Waymo design for laser sensor technology known as lidar, which scans a self-driving vehicle’s surroundings to help it navigate, because Uber’s system is fundamentally different, according to new filings in a federal lawsuit alleging the theft of trade secrets.

Waymo uses a single-lens Lidar. And Uber uses a four-lens device.

“This fact alone demonstrates the misguided nature of Waymo’s request for ‘extraordinary and drastic relief,’ ” an Uber attorney wrote in a filing Friday, adding, “Waymo could not be more wrong, and Uber’s design could not be more different.”

Uber made its argument as it tries to fight Waymo’s request for a preliminary injunction to stop Uber from using what Waymo says are stolen trade secrets, an action that would halt Uber’s progress toward developing a self-driving car, seen as the inevitable future for ride-hailing firms. An injunction “would impede Uber’s efforts to remain a viable business” and potentially put the public in danger, because self-driving cars are safer, the company warned in its court filing.

Waymo filed its suit in February, claiming that former Waymo engineer Anthony Levandowski took 14,000 pages of documents when he left to found autonomous truck start-up Otto, which Uber later acquired.

Levandowski now runs Uber’s self-driving-car project.

Earlier in the week, the case was consumed with the hunt for the 14,000 documents that Waymo says were taken from its system and downloaded onto a thumb drive. The 9.7 gigabits of data contain trade secrets, Waymo says.

Uber attorney Arturo Gonzalez told the court that none of the documents were found on Uber’s servers. He said there was no evidence the documents had made their way into the company’s hands.

“We can’t produce something that we do not have,” Gonzalez said.

But the one place the firm hasn’t haven’t looked is on devices belonging to Levandowski, because he has invoked his Fifth Amendment right to avoid self-incrimination. He has declined to provide information to Uber, his employer.

U.S. District Judge William Alsup warned in court recently that he was unimpressed by Levandowski’s rights claim.

“If you think for a moment that I’m going to stay my hand, because your guy is taking the Fifth Amendment, and not issue a preliminary injunction to shut down what happened here,” Alsup said, “you’re wrong.

The judge also has said he plans to order Uber to allow experts to examine its lidar sensors to see how they measure up against Waymo’s technology.

Waymo said in a statement, “Uber’s assertion that they’ve never touched the 14,000 stolen files is disingenuous at best, given their refusal to look in the most obvious place: the computers and devices owned by the head of their self-driving program.”

Waymo first became suspicious about Uber’s lidar system when an employee was mistakenly included on an email chain that featured a schematic drawing of a circuit board used by Uber. Waymo said it then discovered from documents submitted to Nevada regulatory authorities that Uber was developing its own lidar technology.