Google is suing Uber for allegedly stealing some of its self-driving technology. The online transportation network stands accused of appropriating Waymo’s, formerly Google self-driving car project, LiDAR laser-based scanning and mapping technology.

The San Francisco-filed lawsuit relates to Uber’s subsidiary Otto, which it acquired back in August, and an ‘unexpected email’ which showed Otto’s LiDAR circuit board to bare ‘a striking resemblance to Waymo’s unique LiDAR design’.

“Otto and Uber have taken Waymo’s intellectual property so that they could avoid incurring the risk, time, and expense of independently developing their own technology,” says the suit. “Ultimately, this calculated theft reportedly netted Otto employees over half a billion dollars and allowed Uber to revive a stalled program, all at Waymo’s expense.”

Upon further investigation, Waymo discovered that former Google employee Anthony Levandowski, who founded Otto, had downloaded ‘over 14,000 highly confidential and proprietary design files’ relating to various Waymo hardware systems. These included designs for Waymo’s LiDAR and circuit board. In addition, it found that other former Waymo employees, now working at Otto and Uber, also downloaded confidential information relating to the LiDAR technology.

“We believe these actions were part of a concerted plan to steal Waymo’s trade secrets and intellectual property. Months before the mass download of files, Mr. Levandowski told colleagues that he had plans to “replicate” Waymo’s technology at a competitor,” said Waymo, in a Medium post, explaining the reasons behind the suit.

“Our parent company Alphabet has long worked with Uber in many areas, and we didn’t make this decision lightly. However, given the overwhelming facts that our technology has been stolen, we have no choice but to defend our investment and development of this unique technology.”