License plate reader searches should require a warrant • Hacker News Board

Re: License plate reader searches should require a warrant

#331

Post by arjie » Wed, Aug 12, 2026, 10:34 PM UTC

gs17 wrote: post #307

arjie wrote: post #193

Warrants for historical search with warrant-free flags for ongoing issues seems like a nice middle ground. Convincing. Good article. It seems that would easily impede a lot of abuse and it’s straightforward to believe that historical data is rarely so urgent as to not require a warrant. A matter of defining historical as a sufficiently old enough thing but that seems feasible.

> warrant-free flags for ongoing issues Why couldn't they get a warrant if it's an ongoing issue? It should be really easy, and warrants like that wouldn't take a long time to get usually.

Just for my own epistemic hygiene, would you mind clarifying your familiarity with applying for and receiving a similar warrant and the duration you envision when you say "wouldn't take a long time"?

Very reasonable not to, of course, but it helps me adjust my understanding of things. And yes, if a warrant is a 10 min process at p95 from call receipt to warrant acceptance then that certainly allows for things like "this car was stolen in an armed robbery 20 mins ago; we'd like to track it through the city" without too much concern, and I would switch to requiring such an SLA[0] on warrants combined with a requirement on warrants that can be rescinded if the SLA is violated.

0: strictly nonsensical here, but I think you get the picture

Re: License plate reader searches should require a warrant

#332

Post by dredmorbius » Wed, Aug 12, 2026, 10:38 PM UTC

semiquaver wrote: post #284

kentm wrote: post #29

Earlier quoted context omitted.

> I don't understand why a police cruiser can sit in a public space (or even a private one) and write down licence plates and descriptions of passers-by with pen and paper, or record everything around them with dashcams and bodycams for later use, but when it comes to cameras on a pole this would require a warrant. Scale actually matters. Things that are generally OK at a small scale become problematic at larger scal…

Scale does not matter. Here’s a quote from Chatrie : > Still more fundamentally, we have never understood Fourth Amendment protections as kicking in only once an intrusion “goes too far.” Pennsylvania Coal Co. v. Mahon, 260 U. S. 393, 415 (1922) (adopting that approach for regulatory takings). Where the Fourth Amendment applies, it applies—regardless of “the quality or quantity of information” the government obtains.…

Scale doesn't matter in a clear 4A violation.

Scale does matter in what characterises a clear 4A violation.

Nationwide pervasive cross-referenced AI-augmented ALPR is a 4A violation on account of that scale.

(I'd argue that that relevant scale threshold is far lower, but probably above the single-officer-in-a-single-cruiser manually taking notes level.)

Re: License plate reader searches should require a warrant

#333

Post by jameshart » Wed, Aug 12, 2026, 10:38 PM UTC

malwrar wrote: post #324

jameshart wrote: post #10

Earlier quoted context omitted.

This amounts to an argument against ever using general purpose computing devices to accomplish anything. You could say the same about literally any privately operated device. ‘I don’t know why they call these things cell towers. They do whatever they are programmed to and can be reprogrammed by anyone with access’ Heck the same applies to non electronic things too ‘why do they call it a house? It’s a general purpose…

Interesting perspective. As others have noted, I believe the brightline is less “general purpose computer…” and more “…that is remotely accessible & modifiable effectively anywhere in the world”. I worry not just about OEMs and cops, but also criminals, foreign intelligence agencies, etc. Honestly potentially anyone at this point, now that folks have figured out you can use LLMs to do analysis. This is a sound founda…

I think that’s a very different concern - your take is more ‘governments shouldn’t deploy these things because they are incompetent’ whereas the original concern seemed to be ‘governments shouldn’t deploy these things because they are malicious’.

Neither philosophy seems to have a good limiting principle for what they mean governments should be allowed to do to efficiently enforce traffic law

Re: License plate reader searches should require a warrant

#334

Post by SchemaLoad » Wed, Aug 12, 2026, 10:53 PM UTC

thewebguyd wrote: post #79

malwrar wrote: post #2

It frustrates me when people call them license plate readers. I guess you need to call them something, but they are general-purpose internet connected cameras. They will do whatever their firmware tells them to do, and could be reprogrammed at any time by anyone with access. No one expected doorbell cameras to join a mass surveillance network, but later the manufacturers added that feature. Why do we treat these came…

> Why do we treat these cameras like they can do only one thing? Because its useful messaging to disarm the populace. "License plate reader" sounds less alarming than "Internet connected camera" or "Mass surveillance device." Public attitudes vary around a "license plate reader" but will be more uniformly opposed to "Widespread, automated government mass surveillance tracking your every move via camera in real time"

Security cameras have been internet connected for a lot longer than we had this kind of system where they all have computer vision running and tagging everything in a massive database.

They were always internet connected and mass surveillance. It's the addition of search that changed things.

Re: License plate reader searches should require a warrant

#335

Post by SchemaLoad » Wed, Aug 12, 2026, 10:55 PM UTC

cmiles8 wrote: post #3

Either it needs a warrant or it’s fully open and people can start creating websites showing the movements of local politicians. This middle ground that municipalities try to carve out where it’s fully open to police without a warrant but not subject to FOIL laws doesn’t appear tenable for much longer. There’s been too many cases of police officers stalking exes, poking around the data for fun and such so it’s clear p…

IMO it shouldn't need a warrant, but it should require the searcher to fill out a form explaining which crime they are investigating with this search. It can then immediately show them results without approval, but with serious consequences for misuse.

They could even run some AI over the request forms to spot unusual activity like an officer constantly requesting the location of their ex wife.

Re: License plate reader searches should require a warrant

#336

Post by estearum » Wed, Aug 12, 2026, 10:59 PM UTC

fluidcruft wrote: post #321

estearum wrote: post #310

Earlier quoted context omitted.

You should go read the United States v Jones concurrence and try to figure out why five Justices disagree with you. Have some curiosity about the world! You can also read Carpenter v United States for some background thoughts on why it's not as simple as Justice Fluidcruft condescendingly imagines it to be. In fact if you're really curious, you could even look at the state cases that are bubbling their way up like Co…

idk how installing a GPS tracker is even remotely comparable to taking photographs of publicly visible license plates in plain view in public but please do go on refusing to engage facts.

Ah, someone didn't read the opinions. Shame.

Confidence and ignorance live another day!

Re: License plate reader searches should require a warrant

#337

Post by unethical_ban » Wed, Aug 12, 2026, 11:01 PM UTC

fluidcruft wrote: post #321

estearum wrote: post #310

Earlier quoted context omitted.

You should go read the United States v Jones concurrence and try to figure out why five Justices disagree with you. Have some curiosity about the world! You can also read Carpenter v United States for some background thoughts on why it's not as simple as Justice Fluidcruft condescendingly imagines it to be. In fact if you're really curious, you could even look at the state cases that are bubbling their way up like Co…

idk how installing a GPS tracker is even remotely comparable to taking photographs of publicly visible license plates in plain view in public but please do go on refusing to engage facts.

Both allow cops to track people as they travel without a warrant.

Re: License plate reader searches should require a warrant

#338

Post by SchemaLoad » Wed, Aug 12, 2026, 11:01 PM UTC

MrDrMcCoy wrote: post #251

metalcrow wrote: post #191

I do wonder though if the data retention should be restricted at all. This brings up a very good point that even old data (months or more) can be vital to cases or to the defense, but is there any downside to it that would make it worth restricting? And how long?

I think it should. 7 days without a warrant to retain, and only for the specific purpose of an active investigation following an identified crime.

This seems pretty logical. If a car is stolen, it's fair to allow fast access to it's live location. In the search request they can submit a form saying they are tracking the car after a report it's stolen. The requests can get stored in an audit log with penalties for abuse.

Re: License plate reader searches should require a warrant

#339

Post by vzaliva » Wed, Aug 12, 2026, 11:20 PM UTC

Imagine all licence plates being small screens and periodically showing numbers derived from a private key issued by the DMV. As they change, vehicles could not be tracked without knowing the private key, yet the DMV can verify the ownership because they know one. I am not a crypto expert, and the actual scheme may be a bit more sophisticated, but you’ve got the idea.

Re: License plate reader searches should require a warrant

#340

Post by krapp » Wed, Aug 12, 2026, 11:28 PM UTC

vzaliva wrote: post #339

Imagine all licence plates being small screens and periodically showing numbers derived from a private key issued by the DMV. As they change, vehicles could not be tracked without knowing the private key, yet the DMV can verify the ownership because they know one. I am not a crypto expert, and the actual scheme may be a bit more sophisticated, but you’ve got the idea.

That would be more expensive, as it requires electronics and infrastructure, the screens would be hacked and vandalized constantly, short out in bad weather, etc. It would be more robust just using some kind of transponder, but that might fall afoul of FCC rules, IDK.

Also the cops would just get the private keys from the DMV anyway. It's all the same government.