Driverless cars are becoming more common in some California cities, but when the autonomous vehicles violate traffic laws, police haven't been able to ticket them - until now.

The state's Department of Motor Vehicles (DMV) has announced new regulations on autonomous vehicles (AVs), including a process for police to issue a "notice of AV noncompliance" directly to the car's manufacturer.

The new rules, which will take effect on 1 July, are part of a broader 2024 law that imposed deeper regulation on the technology.

There have been numerous reports of the cars violating traffic laws, including during a San Francisco blackout last year.

The California DMV is calling the new rules "the most comprehensive AV regulations in the nation".

Under the new rules, police can cite AV companies when their vehicles commit moving violations. The rules will also require the companies to respond to calls from police and other emergency officials within 30 seconds, and will issue penalties if their vehicles enter active emergency zones.

"California continues to lead the nation in the development and adoption of AV technology, and these updated regulations further demonstrate the state's commitment to public safety," DMV Director Steve Gordon said in a press release.

Waymo is one of the main operators of fully self-driving robotaxis in the San Francisco Bay Area and Los Angeles County, but several companies, including Tesla, also have permits to test their AVs in some California cities. The BBC has contacted Waymo and Tesla for comment.

When the vehicles violate traffic laws, some police have been stumped as to how to hold the driverless cars accountable.

In an incident last September, police officers in San Bruno - a city south of San Francisco - noticed a Waymo AV making an illegal U-turn at a light directly in front of them, the San Bruno Police Department said at the time. But when officers stopped the car, they were not able to issue a ticket without a driver to give it to. Instead, they contacted the company about the "glitch".

In December, a massive blackout in San Francisco left a number of Waymo vehicles stalled in the middle of busy intersections, worsening an already congested traffic situation.

San Francisco Fire Department officials have also repeatedly complained about robotaxis getting in the way of emergency responses.