Why cops won’t need a warrant to pull the data off your autonomous car

Lt. Saul Jaeger, who commands the traffic unit at the Mountain View Police Department, remembers the first time a few years ago when he was given a demo of Waymo's self-driving cars.

Jaeger was not only interested from a professional point of view, but also as a citizen. After all, he lives in Mountain View near one of the Waymo facilities. He watched in awe as the engineers showed him the autonomous vehicle's (AV) own view. This screen reduces everything to line drawings and other simplified sensory inputs.

"It's incredible," he told Ars. "It felt like The Matrix, when they flip the switch—it's seeing everything, it's seeing way more than you or I can—and it's making decisions."

Jaeger, a veteran of the department, said that as someone whose job requires that he "reconstruct" serious traffic accidents, he could only dream of a machine that captured as much as an AV does.

"I felt like I was in heaven," he said. "It's like instant replay in the NFL, I can tell what happened. The engineers looked at each other like, 'Aw, crap.'"

Instantly, Jaeger realized that the promise of AVs to not only be safer for those inside the car, but it may also, potentially, be a way for law enforcement to collect data and information about everything else around it.

For now, law enforcement in one major hub of AV development and testing seems to have few clear ideas as to how they will integrate these vehicles into their traffic enforcement practices, much less their investigative process.

But AVs could soon become—absent a notable change in the law—a TiVo-on-the-ground. In other words, as auto manufacturers and tech companies race to take AVs mainstream, they may become a gold mine for law enforcement.

What’s the standard?

In order for AVs to work, they have to snag all kinds of data about the world around them: where precisely other objects are at any given moment and how fast they are moving. That data can seemingly be kept forever.

Under current law, all of that data can be obtained relatively easily by federal law enforcement. In other words, if you're a privacy-minded citizen, your threat model just changed.

"Because of all of the sensors and data that is being captured—[AVs] are giant recording things," Jaeger said. "Even if they're not involved in an incident directly, they captured some of it. Maybe infrared data or something."

This is profoundly different from older cars that lack such sensors and do not gather up such vast quantities of stored data. As such, Tesla's terms and conditions—like those of other non-automotive tech companies, including Apple, Google, and more—say that the company will hand over data to law enforcement when legally compelled to do so. Waymo did not respond to Ars' multiple queries for clarification its position, so how far that assistance will go is anyone's guess.

For now, federal law and Supreme Court precedent dictates that law enforcement has the authority to legally monitor anyone in public. The basic idea is that none of us have a "reasonable expectation of privacy" when we are in public. So just as the police can capture us with video cameras and license plate readers, so, too, could they contract with AV automakers to simply get at vast quantities of future AV data. And if the companies don't want to play ball, such data can be accessed with a mere court order (known as a "d-order") under the Stored Communications Act of 1986.

Carpenter v. United States

This is the exact legal issue at the heart of a case currently pending before the Supreme Court, known as Carpenter v. United States.  The case involves phone company records and a string of robberies in Michigan around 2010, but Carpenter essentially asks, does law enforcement need a warrant to be able to access potentially intimate location information? Or, as the government has claimed, is such data easily accessible to law enforcement under the increasingly-anachronistic third-party doctrine?

"There is nothing to stop a federal agency from requesting location data from an autonomous vehicle maker," Catherine Crump, a law professor at the University of California, Berkeley, told Ars.

She pointed out that, while Article I, Section 1 of the California Constitution explicitly grants a right to privacy to all citizens of the Golden State, "it's not an absolute right."

"It can be outweighed where the government has a legitimate interest that is furthered by the privacy invasion," she continued. "It's not hard to imagine all sorts of sympathetic circumstances in which we would want the government to have access to location data. The best way to handle this is probably through legislation."

California does have a relatively new law, known as the California Electronic Communications Privacy Act (2015), which does impose a warrant requirement to access location data. So state and local authorities in the Golden State, at least, would likely have to clear the warrant hurdle before getting at such data.

As of today, there appears to be no publicly-known instance of law enforcement going to an AV manufacturer, with a warrant or otherwise, to obtain data.

"The federal government would likely argue that it is not constrained by state constitutional protections," said Nathan Freed Wessler in an email to Ars. Wessler is the American Civil Liberties Union lawyer who represented Carpenter before the Supreme Court.

But there may be a silver lining.

"If the Supreme Court rules for the government in Carpenter, I anticipate more states will pass laws like CalECPA," Geoffrey King, a UC Berkeley lecturer and attorney, told Ars.

A Waymo vehicle during testing. In this scenario, a car unexpectedly backed out in front of the Waymo self-driving van. The Waymo vehicle was able to stop even though the reversing car was initially mostly obscured by another car in front of it.

Credit: Waymo

No one’s got a clue

At present, Silicon Valley law enforcement agencies that operate near AV testing facilities say that they have no specific AV policies. That means it's not clear exactly by what means law enforcement would try to obtain AV-related data held by a future itinerant Uber-like company, or by an AV owned and operated by an individual.

The California Department of Motor Vehicles has proposed that there be a standard way that autonomous vehicles manufacturers communicate with first responders and law enforcement, but no standard has officially come into force yet. The issue was raised briefly during hearings held in Sacramento earlier this year.

For years, Waymo and Google have been reaching out to local first responders (including Lt. Jaeger) to educate them on how their AVs work in practice. In June 2015, for example, Google showed that its AV had an emergency "E-stop." But they seemingly have not explained to the public how Waymo might interact with law enforcement.

As of 2018, all California AVs driven on public roads must have a human driver ready to take control at all times. So police continue to generally treat AVs as they would any other car. The California Highway Patrol, which is a state-level law enforcement agency, said that "AV policies are not yet developed."

"The development of autonomous vehicle (AV) technology is changing fundamental aspects of transportation and could lead to marked improvements in traffic safety, mobility, and the reduction of traffic congestion on the roads of California," Fran Clader, a CHP spokeswoman, emailed Ars in a statement. "The California Highway Patrol (CHP) is committed to providing the highest level of safety, service, and security to California."