If you’ve spent any time in a city council meeting lately, you’ve likely heard someone recite this phrase: “there’s no reasonable expectation of privacy in public.” It is intended as a conversation-ender, the legal equivalent of a shrug and a wave of the hand. A citizen raises a concern about a new license plate reader bolted to a pole at the entrance to their subdivision, and a councilman, law enforcement leader, or an ALPR company representative answers with that line as if the matter were settled some forty years ago and there’s nothing left to discuss.
It’s good to know where this line comes from, because the case from which it originates says much more than the isolated sound bite intimates.
1983: The chloroform in the trunk
The line traces back to United States v. Knotts, decided by the Supreme Court in 1983. Minnesota narcotics investigators suspected a man named Armstrong of buying chemicals to cook illegal drugs. With the seller’s cooperation, they hid a radio transmitter, a “beeper”, inside a container of chloroform before Armstrong retrieved it. From there, agents followed the car by sight and by signal as it made its way from Minneapolis to a cabin in rural Wisconsin (owned by the defendant, Knotts), where they eventually found a drug lab.
Knotts argued that tracking him this way without a warrant violated his Fourth Amendment rights under the U.S. Constitution. The Court disagreed. Writing for a unanimous bench, Justice Rehnquist reasoned that a person driving on public roads has already made his movements visible to anyone who cares to watch. The beeper, in the Court’s view, was no different in kind from an officer trailing the car with a good pair of binoculars. The technology just made the officers’ job easier. That’s the origin of the phrase everyone quotes:
A person traveling on public thoroughfares has no reasonable expectation of privacy in his movements.
Fair enough, as far as it goes. However, this is not where the full opinion ends.
The Raincheck Clause
Buried in the same paragraph, Knotts’ own legal brief warned the Court about exactly what a ruling like this could enable down the line. His attorneys wrote that if the government’s argument won, “twenty-four hour surveillance of any citizen of this country will be possible, without judicial knowledge or supervision.”
The Court didn’t dismiss this as paranoia, nor did it even appear to disagree. What it said instead was that the “reality hardly suggests abuse,” and that if “such dragnet-type law enforcement practices as respondent envisions should eventually occur, there will be time enough then to determine whether different constitutional principles may be applicable.” [emphasis mine.]
Read that again.
The Court wasn’t closing the door on Knotts’ concern but was rather punting it. It said, in effect: that future you’re describing isn’t here yet, so we don’t have to rule on that today. Should it arrive, the courts will take a fresh look then.
In this way, the Court ultimately issued a raincheck on the issue. Interestingly, the word the Court chose to describe the future it was declining to rule on at the time was a specific one: dragnet. Not “widespread” or “extensive.” Dragnet, a word that means sweeping up everyone in an area regardless of individual suspicion, or whether they’re a person of interest or not. The justices in 1983 had a fairly precise picture in mind of the criteria that would eventually force them to reconsider, and even put a name to it.
Cashing the check
It is now forty-three years later, and most people looking honestly around their own communities would likely agree that future has arrived.
Automated license plate readers (ALPRs), the kind sold by companies like Flock Safety and Axon, tread far beyond a single beeper hidden in a single drum of chemicals tied to a specific ongoing investigation. They are fixed or mobile cameras logging every license plate that passes, whether the driver has ever been suspected of anything or not. The data collected stored in databases, owned and controlled by private companies, that are searchable other agencies across the country. A single one of these networks can process billions of scans per month. This involves more than tailing a suspect; it creates a searchable record of where nearly everyone goes, built and installed without any individualized suspicion at all, which is close to a textbook definition of a dragnet.
The comparison to law enforcement following a car isn’t quite honest anymore, either. A police officer trailing a vehicle has a finite shift, a limited fuel budget, and a supervisor who eventually asks why the overtime is so high. A camera network doesn’t get tired, doesn’t need a warrant to keep running, and doesn’t forget. The Court’s whole argument in Knotts rested on the idea that the beeper was just a stand-in for an officer’s own eyes and legs. Once you’re logging millions of people a day into a searchable, retained database, you’ve now built something categorically different from an officer with a good pair of binoculars, and pretending otherwise is where I think the “no expectation of privacy” line gets stretched well past what it was ever meant to cover.
Furthermore, the technology continues to expand past even this. Many of these camera systems are being fitted with add-on sensors that pick up individually identifiable Bluetooth, Wi-Fi, and other wireless signals coming from phones, earbuds, and smartwatches inside passing vehicles. This practice shifts the entire premise of the system as it has been intially presented. It becomes no longer about identifying a license plate, but about identifying the specific people riding inside the car, whether or not they’re the registered owner, whether or not they’ve done anything to draw attention, etc. The device evolves from being a license plate reader and starts being a people-tracking surveillance checkpoint that happens to be mounted near a road.
Why this should matter to you, regardless of politics
I’d ask you to set aside, for a moment, whatever your priors are about policing generally. This is not a partisan issue, and treating it as one is perhaps partly how these systems get installed without due public conversation or consideration. A searchable record of where every driver in an area has been doesn’t discriminate based on who’s asking to see it. It’s just as available to a well-meaning detective solving a hit and run as it is to an agency doing immigration sweeps, an abusive ex-partner or bad actor with a badge and access to the system, or whoever ends up running these databases twenty years from now under laws and politics none of us can predict today.
These are all valid arguments for caution here, and the latter is the same one Knotts’ lawyers made in 1983: it’s not really about whether today’s use is reasonable, but what the infrastructure makes possible once it exists, because infrastructure, once installed, tends to outlast the specific justification that got it funded.
You can be sure the vendors lobbying your local councils and/or agencies for this technology are well aware of this.
What you can actually do about it
Regardless of where you land on this issue, none of this requires you to become a constitutional scholar. It mostly requires showing up. Camera contracts get approved at city council and parish/county council meetings, often with very little public comment because most residents don’t know the vote is happening. Find out if your town already has this technology, and if it doesn’t yet, find out if it’s on an upcoming agenda somewhere near you.
A few places to start:
- DeFlock — a crowdsourced, open map of ALPR camera locations across the country, so you can see what’s already installed near you.
- EFF’s Atlas of Surveillance — a broader project from the Electronic Frontier Foundation tracking surveillance technology used by police departments nationwide, including but not limited to license plate readers.
Read your city or parish/county/city council’s meeting minutes. Ask your local police department, in writing, whether they have a contract with an ALPR vendor, and if so, ask for the data retention policy and who else has access to the database. These are public records requests any resident can make. You don’t need permission to ask.
The Supreme Court told us plainly in 1983 what would eventually force a second look. We are the generation that gets to decide on taking that look, or whether to let this raincheck expire unclaimed.