Legalities of automated license plate readers for speed limit enforcement.

Without falling into a discussion of what we all think of speed limits, their enforcement, police officers and The Man in general.

Is it legal to use automated license plate readers to enforce speed limits? Meaning, you read all the plates of the cars passing a certain point, then further down the road you check for them again and see how long they took to traverse that segment. If they did it under the time it would take to do it at the legal speed limit, then ticketing ensues.

It produces a lot of false negatives (people who broke the limit momentarily but averaged less than the speed limit), but it nabs what I think are the worst offenders, which are the ones who don’t just speed a little but consistently drive above the speed of traffic.

Of course this varies with location. I just would like to hear if this is being used anywhere and if there are locations with specific laws against this (or be unconstitutional or something).

I would also welcome studies (or even well explained cases, not opinions) on the effectiveness (or lack thereof) of this method.

Thanks in advance.

I’ve never heard of this particular method of traffic enforcement, but I don’t see any legal problems with it. A long line of U.S. Supreme Court cases has held that your privacy rights while in a vehicle are considerably more limited than in your home. A license plate is exposed for all to see, and if the scanning system is proven reliable, I think it would likely pass muster.

I’m not aware of this in use anywhere, but it would just be a varient of using aircraft for enforcement. In aircraft enforcement, the observer starts a stopwatch when you cross a fixed ebservation point and then stops it when you reach another. Get there too fast and they either have a ground unit pull you over or mail a ticket to the registered owner.

I admit I really haven’t thought it through, but on the surface it wouldn’t seem to be any different from using a radar gun.

It is funny that you say “on the surface” when the alternative offered is aerial surveillance.

Anyways, I guess the obvious difference would be that it is a massive always-on, every-car system as opposed to a guy finger picking examples and not keeping track of anything.

I hadn’t thought of aerial surveillance as a comparison (having lived in an area where it was used). Is it done by a guy tracking you manually?

The gist of my question is about the “every car counted” aspect of it. I guess the privacy issue would be easy enough to address if you can convince the (privacy oriented) public that no record is being kept and that the system cannot be used to pick a car from the mass.

**Elendil’s Heir **addressed the privacy issue, but to add to it, the surveillance camera at a convenience sotore is always on, so every customer is recorded. Same with a bank, hospital, etc. Is that a privacy issue? Pretty much whatever you do in public is not a private matter, by definition.

I’ve got no problems with it, assuming it can be done reliably.
Passes the “does Todderbob have a problem with it,” legal muster, at least. :stuck_out_tongue:
I also don’t think there’s a constitutional issue… rights to privacy and such counting in public.

They’re unconstitutional in my state (Montana), along with red light cameras, precisely because they violate our explicitly enumerated right to privacy in our state constitution. Also, just to be sure, the legislature passed a law against them.

In many states “time over distance” traps are illegal, with the only exception being made for air enforcement. The way I’ve always interpreted this is that back before radar, people just wanted to do away with speed traps in general, but that public outrage had waned by the time radar came on the scene and they never bothered making that illegal too. But that’s just me speculating.

They are a HUGE subject here in Arizona. Personally, I don’t know why people don’t just slow the f*&% down, and stay AT the limit, but they get all bitchy when the camera clocks them doing a minimum 11MPH over the speed limit of 65MPH (so they are doing 76). The alternative they suggest, of course, would be to hire actual patrolmen to do the work, but of course the legislature refuses to fund them either. So, what is a state to do?

I don’t know how the law is going to deal with it, nor does the state. The tickets continue to pile up, but the pressure is on to dump the whole program (and the millions it cost).

Lots of people here refuse to pay the tickets. One worker was shot and killed as he worked on the freeway (the shooter was caught). There are various reports of some people being sought out and served with papers. I’ve know some people who did not pay and got hung up later at MVD come auto registration time. Some wear masks on the highway so they can’t be “legally” identified. They are all morons if you ask me.

Actually, my Facebook picture is a speed camera shot. I paid it.


Sorry, OP, I should have not gone on about the discussion of my opinions. Apologies, too late to edit.

But it is an interesting story, and bouncing around in the local news a lot.

Well, for many a year, when I used to drive the 95 corridor often up and down the east coast of the US, there were signs posted in many places … “Speed Monitored By Helicopter”, and there used to be chase cars later on to pull you over. So, in this case, I see no difference, except efficiency.

I don’t see any privacy issue at all personally. Whether I like it or not, driving a vehicle is a privilege, not a right. If you get nabbed speeding, well, deal with it (except for those small-town speed traps, I have much h8 for them, even though I’ve not yet been stopped).

As an aside, the “every car counted” aspect might not be all that bad, if the data is used in appropriating necessary funding for road development, and additional infrastructure.

And, what is the difference between a system as described, and the “Red Light Camera” systems popping up in so many cities now?

Another ‘like it or not’… people exceeding speed limits, or not observing road rules cause a LOT of accidents.

Then there is yet another reason I can see for this type of system… In the US, Federal Highway Dollars are often doled out depending on a state’s compliance to highway safety, and with state, county, and municipal dollars being cut so drastically, they need to become more efficient in demonstrating compliance in order to receive the Federal Money!


In many municipality/county cases around here (to add to my last point), they put up those big flashy radar-gun signs “Your Speed Is xx”, in trouble areas, but have no actual enforcement. The sign itself becomes a modification to driving habits.

If a guys truck is really muddy, :wink: the license may not be easily read from a distance. :wink: That trip to deer camp can pay off, at least until it rains.

I’m unaware of monitoring occuring in the method the OP states. I’ve always just seen cameras with radar attached. Seems much more efficient.

There are a lot of scam products that claim to obscure the license plate. Mythbusters tested several. No surprise that none fooled the camera. Some of the devices were probably illegal. The penalty for using them was worse then the traffic ticket.

The issue I have with this is the same as I have for a red light camera ticketing system.

The tickets are for the owner of the vehicle, not the driver.

If I get into someone else’s car, and break the speed / red light laws, they get hit with potentially thousands of tickets. That just isn’t fair at all.

In the heli example above, there was a chase car which apprehended the vehicle immediately after the violation, yes? This allowed the offending party to be penalized, not someone who may be in a coma(i know, i know, bad example…).

Whether such a method is legal depends on state law so we’d need 50 answers.

49 to go

BTW why is it considered to be a privacy violation, but it wouldn’t be a privacy violation if a cop were sitting there in his car with a dozen donuts in his lap clocking with radar every car that went by?

Perfectly legit. Th machine is simply doing what anyone standing by the road could do. Looking at cars and reading the number plates is perfectly fine.

No problem with legalities over here in Australia (What?.. Nobody specified the US!)

We have them in some states, but not all. My particular state only has them recording data for heavy vehicles (the argument being that heavy vehicles are over-represented in fatalities). One day they’ll change that to all vehicles, I’m sure.

Beats me. I think it’s just the photographing every car aspect (even though only scofflaw cars get photographed in the case of red light cameras). Perhaps the concern is that an overzealous police force could use such a system to keep track of every car that goes past the cameras to track people’s movement. So to follow your example, it’s okay for the cop to sit there watching for speeders, but the cop couldn’t sit there and take pictures of every car that went by.

I believe a British friend told me that this is actually done in the UK.

He also said that the poles that held the scanners were frequent vandalism targets.

Brit Dopers are invited to elucidate and/or correct me on either point.