GM is being sued after an autonomous Chevy Bolt was involved in an accident with a motorcycle in San Francisco.

General Motors Co. is facing a lawsuit by a motorcyclist, who says he was hit by a Chevrolet Bolt, which was operating in autonomous mode with a backup driver behind the steering wheel.

The motorcyclist claims the Chevrolet Bolt operated by Cruise, GM’s self-driving car subsidiary, “suddenly veered back into motorcycle’s lane, knocking the bike to the ground.”

The accident happened on Dec. 7, in heavy traffic in the Hayes Valley district of San Francisco, with the GM vehicle reportedly travelling at 12 mph and the motorcycle 17 mph. The accident report filed after the accident contradicts the claim made in the lawsuit.

The police report states that the autonomous vehicle was driving in the center of three one-way lanes. It attempted to move into the left lane when the available space was truncated by braking traffic, causing the GM car to abort its move and return to the center of the middle lane.

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“As the Cruise AV was re-centering itself in the lane, a motorcycle that that had just lane-split between two vehicles in the center and right lanes moved into the center lane, glanced the side of the Cruise AV, wobbled and fell over,” according to the report by the investigating officers.

“The motorcyclist was determined to be at fault for attempting to overtake and pass another vehicle on the right under conditions that did not permit that movement in safety.”

The motorcyclist was able to walk his bike to the side of the road before exchanging information with the GM car’s occupants and receiving medical care for shoulder pain. GM said that it intentionally tests its self-driving vehicles in challenging conditions, but safety is always a primary concern.

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The company has been testing its autonomous vehicles in San Francisco since August, allowing employees to hail the cars with a backup driver behind the wheel. Its cars were involved in six no-fault collisions in September.