A week-long clash between California regulators and Uber over the company’s self-driving cars culminated Wednesday with officials revoking the vehicles’ registrations after the state deemed them to be operating illegally. That move put a halt to Uber’s testing of autonomous vehicles in San Francisco, at least until the company agrees to obtain permits required by the state.

The bumpy week saw accusations that Uber’s self-driving cars broke basic traffic laws and complaints from cyclists that the cars were unsafe additions to the roadway.

The suspension of service comes as Uber looks to expand the use of self-driving cars as part of its popular ride-hailing service.

In case you haven’t been following every twist and turn of the issue, here’s what you need to know and why it matters even if you don’t live in San Francisco.

When did Uber start testing self-driving technology in San Francisco? Why? 

Uber formally announced its self-driving program in San Francisco on Dec. 14, though the company has been testing the cars on roads there for a month. The self-driving cars — Volvo XC90s equipped with a system of lasers and cameras for guidance — included an engineer and safety driver, who could take control of the vehicle if necessary.

Compared with Pittsburgh, San Francisco presented Uber with a new set of challenges for its self-driving technology. For one, it is a smaller city with major traffic congestion. It also has a strong culture for alternative transportation, meaning the car would share the road with a bevy of cyclists, street cars and buses.

But the program was public less than a day before the Department of Motor Vehicles told the company to shut it down. If Uber did not comply, the DMV threatened legal action that would force the company to do so.

Just one week after it started, Uber's self-driving car program in San Francisco is over. (Reuters)

Why did California regulators consider those tests to be ‘illegal?’

California law requires entities that test self-driving technology on public roads to obtain a special permit, and provide proof that they are financially and legally responsible for any issues that arise. Those companies must also disclose when self-driving cars are involved in accidents or when a human driver must take control of them.

“These requirements serve to build public trust in the safety of the technology and to foster confidence in allowing autonomous vehicles on public streets,” Brian Soublet, the department’s deputy director and chief counsel, wrote in a letter.

Uber disagreed and debuted in San Francisco without obtaining permits.

What happened most recently and why does it matter?

On Wednesday, California’s Department of Motor Vehicles revoked the registrations for Uber’s self-driving cars.

“It was determined that the registrations were improperly issued for these vehicles because they were not properly marked as test vehicles,” regulators said in a statement. “Concurrently, the department invited Uber to seek a permit so their vehicles can operate legally in California.”

Those permits have already been issued to 20 other companies testing autonomous vehicles in the state, regulators said, including Google, Ford, General Motors and Honda, among others. Once an application is submitted, permits are typically issued within three days.

“The department stands ready to assist Uber in obtaining a permit as expeditiously as possible,” regulators said Wednesday.

What other issues did Uber’s program encounter in San Francisco?

A business owner there claims that a self-driven Uber vehicle ran a red light and nearly caused a collision, according to The Guardian. Uber denies the claim and said traffic errors have been the fault of the human drivers operating the vehicles.

What’s more, the San Francisco Bicycle Coalition raised concernS about whether Uber’s technology would cause cars to cut across the bike lane when making a right hand turn, rather than merging into the lane and accommodating cyclists. A petition asking Uber to address the complaint garnered hundreds of signatures, KCBS reported.

What will Uber do now? 

To start, Uber shipped its self-driving cars from California to Arizona on Thursday morning. The company plans to begin testing them there in the next several weeks, a spokeswoman for the company said.

Executives do not have immediate plans to obtain a California permit. “We are open to having the conversation about applying for a permit, but Uber does not have plans to do so,” the spokeswoman said.

Uber maintains that its cars do not meet California’s legal definition for autonomous vehicles because they require a human driver to be present at all times. The company also accused regulators of inconsistent enforcement of the permit requirement because Tesla’s cars equipped with driver assist technology do not require permits. (Tesla Motors is listed among the companies that have obtained permits from the state.)

I don’t live in San Francisco. Why should I care? 

The self-driving car movement isn’t just taking hold in tech meccas like San Francisco. Uber’s self-driving program actually started in Pittsburgh. Michigan recently passed legislation that will allow automakers to test self-driving technology on the public roads there, and General Motors already plans to take advantage of that this winter. An increasing number of states have already passed legislation allowing at least some testing of autonomous driving, and more are poised to do so when their governments meet next, according to the National Conference of State Legislatures.

In short, this technology could soon be coming to a road near you.

The Switch's Brian Fung got a front row seat (or really, a back seat) demonstration of Uber's self-driving vehicle launch in Pittsburgh. (Daron Taylor/The Washington Post)

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