Uber appears to be standing their ground and not planning to conform to the California Department of Motor Vehicles’ request for them to acquire a permit first before testing its self-driving cars on the streets of San Francisco.

The DMV explains that it approves the responsible exploration of self-driving vehicles; however, the permit process for testing the technology will ensure public safety.

See also: Uber’s self-driving fleet in Pittsburgh goes live

Furthermore, the DMV said twenty other car-makers “have already obtained permits to test hundreds of cars on California roads. Uber shall do the same.”

Uber began testing its autonomous cars with passengers in Pittsburgh back in September, and the ride-hailing company made the decision to expand the experimental project to San Francisco, beginning on Wednesday.

“Starting today, riders who request an UberX in San Francisco will be matched with a Self-Driving Uber, if one is available,” Uber stated.

But the company disagrees with the need to have a permit to proceed with testing, explaining that those rules only apply to vehicles that can drive without a person in charge and monitoring them.  They believe that since their vehicles are still in the early stages, and not yet ready to drive without a person monitoring them, that they should be except from needing this permit.

Of its testing in Pittsburgh, the company says, “Self-Driving Ubers have a driver in the front seat, because the vehicles require human intervention in many conditions such as bad weather.”

Uber threatened by DMV with legal action

The DMV disagrees with Uber, citing California regulations that establish that a permit is necessary for testing an autonomous vehicle on public streets, and has threatened legal action if Uber does not agree to stop its testing in San Francisco until it has acquired the needed permit.

“The permitting requirement serves the important public policy objectives of ensuring that those testing the vehicles have provided an adequate level of financial responsibility; have adequately trained qualified test drivers on the safe operation of the autonomous technology; and will notify the DMV when the vehicles have been involved in a collision and specify the instances when the technology had to be disengaged for safety reasons,” explains the DMV in a letter sent to the company.

Along with the lack of a proper permit, Uber’s trials in San Francisco hit another glitch, too. One of its cars – a Volvo XC90 – was videotaped running through a red light. The company states that vehicle is not part of the pilot program.