Langley, the founder and CEO of Flock Safety, is an unlikely spokesperson for the dangers of the surveillance industry: His company says it has deployed more than 120,000 roadside cameras across 49 states. But in August, while defending his products and policies, he perhaps inadvertently showed why Americans should be alarmed by this technology.

My own sleep has been troubled by the private surveillance industry for more than a decade. In 2014, three years before Flock was founded, I warned in The Atlantic that mass surveillance of all car trips was nearly upon us. I noted that private companies were deploying automatic license-plate readers, or ALPRs, at scale on America’s public roads, threatening a privacy we’ve always enjoyed, and that Congress should regulate the fast-growing surveillance industry. Today, if you drive in much of the continental United States, Flock may profit by selling others the means to reconstruct your movements.

Opposition to this form of surveillance is now a plurality position, according to an August YouGov survey, which found that more Americans oppose the technology’s use in their neighborhood than support it. Politicians in both major parties are criticizing ALPRs, whose name has become something of a misnomer: The cameras can capture detailed images of passing vehicles, not just of the license plate. And anti-Flock activists who track clients of the company list scores of past and potential clients that have canceled their contracts or deactivated cameras in recent months.

“I’ve never really seen such a grassroots uprising against surveillance technology,” Jay Stanley, an ACLU senior policy analyst, told The Guardian. “On the left, there’s a historical memory of law enforcement spying on and interfering with advocates for social change … On the right, there’s a long tradition of ‘don’t tread on me’—keep the government out of my life, keep it from looking over my shoulder.”Still, most of Flock’s network and its competitors’ cameras remain in place.

And fans of the technology want to keep it that way; they argue that there is no reasonable expectation of privacy on roads, and that a network of cameras that logs every passing vehicle is a vital tool for catching criminals. Most surveillance boosters don’t deny that serious abuses have happened or wholly dismiss privacy concerns. Instead, they urge the use of safeguards and the passage of regulations to address them.

But this technology is already ubiquitous. States and localities should not permit its dangers to persist in the hope that one day, our often passive legislators will act. Instead, Americans should work to ban mass surveillance of public roads in every jurisdiction where they can secure support from elected officials until strong protections are in place. The pro-surveillance coalition has significant political influence, and some of its members employ accomplished lobbyists. The only way that it will hasten privacy safeguards is if doing so is the only way to sustain the surveillance business.

Before sketching out what specific legislative protections could look like, it’s helpful to notice that popular debates about ALPRs overstate their likely benefits and understate their dangers. The primary benefit––they help catch some criminals––will grow less effective over time as knowledge of the technology and how to evade it spreads. For example, license plates are already being cloned. And as the benefits decline, the cost that law-abiding citizens pay in lost privacy will persist.

It may even increase. After all, the business model––pay us and we’ll help you catch criminals––creates a powerful incentive for surveillance companies to address falling effectiveness with new privacy intrusions. Flock may eschew facial recognition today, but no federal law prevents it from changing its mind tomorrow, or requires that it alert the public before introducing a new tool.

While evidence remains limited that ALPRs reduce crime in general or violent crime in particular, there is solid evidence that they reduce car theft: A working paper, published in August by the criminologists Scott M. Mourtgos and Ian T. Adams, found that ALPR networks are associated with an 11 percent decline in such thefts and an increase in arrest clearance (though they cautioned that clearances were already rising in the weeks before camera deployment). But if vehicle owners installed their own trackers, benefits could be had for all who opt in without imposing costs on everyone’s privacy.

Some dangers of roadside cameras are well understood. The Institute for Justice maintains a database of known and alleged police abuses of the technology, including stalking and wrongful stops. And although Flock’s rollout of Audit Assistance, the tool that helps catch abuse by cops, redounds to the company’s credit, it is no cure-all: It “detects abnormal activity and flags it for Administrator review,” a Flock spokesperson clarified to me by email, which “refers to review by an authorized administrator at the customer agency—not a Flock administrator.”This leaves open the possibility that abuse will remain undisciplined by some police departments.

A less widely understood danger is what might be called the foreign-adversary problem. China, Russia, and others have real incentives for gaining access to data collected by license-plate readers. Doing so could assist hostile actors in recruiting assets, blackmail, intimidation, and more. Breaching Flock would be the biggest prize––and the public is in no position to evaluate how competently the company or its competitors secure their data.

If Edward Snowden could make off with the NSA’s most sensitive secrets, a systems administrator at Flock or a competitor could theoretically attempt a large-scale theft. The company (let alone the public) may not even know about it.

That worst-case scenario aside, a hostile foreign actor could do damage to U.S. interests merely via the access that normal Flock clients enjoy. Thousands of law-enforcement agencies use Flock. That means thousands of targets for incidents such as a phishing attack, well-placed bribe, or blackmailing a corrupt county sheriff.

What specific legal safeguards would justify the use of this technology? Figuring that out requires distinguishing between two different ways road cameras might operate. Say that a 1961 Ferrari 250 GT California Spyder is reported stolen by its owner when he arrives home from work to find the car missing from his garage, and the Highland Park, Illinois, police department puts its license plate, NRVOUS, on a “hot list” of missing vehicles.

In one approach, Chicago-area license-plate readers could (if the local regulatory scheme allowed it) scan all passing cars for “hot” plates, and instantly delete data on all vehicles that are not a match.

If a collect-and-store-it-all approach endures, equally comprehensive safeguards are justified. First, companies should be permitted to retain data for no longer than a week, on encrypted, local servers; retaining data longer than permitted should be a crime. Authorization by a city council or county board of supervisors should precede installing cameras in any jurisdiction and constrain how that data are shared. And periodic reauthorization votes should be required.

Second, the federal government and all of its agencies should be banned from deploying ALRP technology on public roads or from accessing data collected there.

Third, state and local police should be required by statute to get a warrant to query ALPR data, whether or not federal courts consider these queries Fourth Amendment searches.

Fourth, permissible reasons to query the data should be limited––for example, to investigating felonies or missing or endangered persons, or responding to imminent threats of serious injury or death. And all queries should be made by a named person whose actions can be audited.

Fifth, every camera should beed with the DMV in the state where it is located, display a physical license number on the device itself, and appear on a publicly accessible map that shows the location of all devices that capture data on public roads.

Sixth, individuals should have a right to know that their license plate was queried, by whom, and for what reason; to obtain records stored on their plate; and to compel deletion and payment of damages if the record was collected unlawfully or retained beyond statutory limits.

Seventh, as Mike Fox of the libertarian Cato Institute suggests, Congress should pass a law that authorizes victims of automated-surveillance errors to sue technology vendors for damages.

What’s more, significant harms related to ALPRs have already materialized. Mass tracking by the federal government is reality rather than speculation: Last year, the Associated Press reported that “the U.S. Border Patrol is monitoring millions of American drivers nationwide in a secretive program to identify and detain people whose travel patterns it deems suspicious,” and that “suddenly, drivers find themselves pulled over” and are “aggressively questioned and searched, with no inkling that the roads they drove put them on law enforcement’s radar.”

And a 2015 investigation by the Electronic Frontier Foundation found that “100 ALPR cameras in Louisiana, California and Florida were connected unsecured to the internet, many with publicly accessible websites that anyone could use to manipulate the controls of the cameras or siphon off data.”Details from a few entries in the Institute for Justice database of alleged police abuses help to convey their gravity: A Georgia police chief allegedly tracked an ex-girlfriend and her teenage daughter about 600 times.

In Texas, a deputy reportedly used data from tens of thousands of Flock cameras to find a woman accused by her partner of having an abortion (the deputy later claimed that he made the search out of concern for the woman’s welfare). In Lenexa, Kansas, police reportedly tracked “a writer who wrote a column critical of them,” whom they also suspected of hanging anti-police posters on city property (which the writer has denied). In Toledo, Ohio, an innocent driver was attacked by a police dog, held at gunpoint, and jailed for hours after a Flock camera misread a digit on his license plate (the Toledo police said that they took “appropriate administrative action” after the incident, which included a “verbal reprimand” for the officer involved).

Getting a new privacy law through Congress is hard. Preventing its passage or watering down its provisions is easy. As a result, the intrusions on privacy just keep growing. But if people who favor and even profit from mass surveillance confronted state and local bans until adequate federal protections were in place, they would suddenly have a powerful reason to push for the speedy passage of new privacy rules. That change in incentives may be the best hope for Americans who see how quickly technology is changing and want to stand athwart the surveillance state, yelling Stop.