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Six questions about license plate scanners

Posted by Thomas Nephew on February 16th, 2009

On the neighborhood listserv, a DC police officer wrote in with factual information about how he uses a scanner in his work.  As I wrote him,

Thanks very much, [sir], for describing how the scanner / tag reader works: plates encountered by your car’s tag reader are compared to an onboard database of wanted license plates. It’s also good to know that matches are double-checked in the way you describe. Takoma Park police should no doubt do as DC police do in those respects if the city authorizes the system.

But your explanation doesn’t address some of the key civil liberties issues. Among the big questions (for me, at least) are:

(1) whether the system is always on or whether you turn it on only when you suspect a car is stolen,
(2) what happens with the images of unmatched license plates — likely 99.9% of the plates the tag reader encounters each day,
(3) recourse to the court system to safeguard against abuse,
(4) where do the lists of suspect vehicles come from — it’s not always just stolen cars,
(5) can bad guys trick the scanner, and what consequences does that have for the real value of the system, and
(6) what alternatives were considered and how the decision process should have worked.

I take up each of these questions below.

(1) Always on?
This may sound like a fine point, but do DC police turn the system on only when they suspect a nearby car may be stolen, or am I right to think it is on pretty much all the time?

If the latter, even with all the protocols described — doublechecking over radio that a plate is wanted, and so forth  — the search itself is unreasonable (because literally unreasoned) . Now I know that some people (and some courts) argue this kind of thing isn’t a search or seizure as understood by the 4th amendment. All I can say is that I think it is, kind of like that old New Yorker cartoon with the little girl saying “I say it’s spinach, and I say the h— with it.” There was a reason for opposing unreasonable searches and seizures in 1776, and for codifying that in 1789-1791. Maybe we should now update that understanding in 2009, at least in Takoma Park, by saying we don’t want it done by the government on autopilot either, even for seemingly public data.

(2) Data to be stored?
I don’t know what’s done in DC, and I don’t know for absolutely sure what the TPPD’s plan would be. But I was told that the 2 leading systems being considered are PlateScan and ELSAG. When I looked at those manufacturer’s web sites, the systems they sell envision retrospective surveillance; Capt. Coursey, in his briefing, also mentioned this possibility, as did the initial announcement on the PEN list. In this case, license plate images (and/or the recognized license plate text “XYZ 123” plus time plus location) that weren’t immediate matches would nevertheless be stored. This data could then be compared to new incoming “wanted” plate data, and the past whereabouts of a given wanted car could be traced.

That might not sound so bad, except that unless such data is immediately purged, you wind up storing a kind of ongoing movie of cars in Takoma Park — of you, of me, of demonstration-goers, of mosque visitors, of cars parked outside CASA de Maryland. Given the PATRIOT Act, national security letters, and the data-vacuuming approach of agencies like the NSA, such data could be secretly and completely acquired, and used for whatever purpose struck the NSA or FBI as worthwhile at the time. And you and I would not know about it. The only way to prevent that would be either not to store any data whatsoever — or not to get the system in the first place.

(3) Can we insist on judicial review?
What if data is stored anyway? Whether the initial scan can be considered a reasonable search or seizure or not, reviewing stored data should surely require a judicial warrant to prevent abuse. However, it’s not clear to me that Takoma Park can demand a Maryland court rule on a warrant request just because City Council might like them to — that safeguard may be something only Annapolis can provide, not Takoma Park.

(4) What database sources are used?
The TPPD grant proposal for the scanner system is specific about only one class of database as a source of wanted plates — those of suspected terrorists. Given that nuns, anti-death penalty sportswriters and environmentalists have been labeled as such, this was not impressive to me. The question is which databases supply the lists of wanted plates on DC scanners or that of the TPPD.

(5) Can the scanner be tricked?
One report I saw out of the UK indicated that police are complaining about bad guys altering license plates — sometimes just with tape. There will be great incentives for bad guys to find ways of defeating wholesale surveillance systems, and they are likely to find ways to do so — altered plates, fake plates, swapped plates. The rest of us won’t do that. If so, systems like this will increasingly only those for whom evasion isn’t worth the penalty. In Arlington, scanners were apparently pressed into service to collect late library book fees, at least in 2004.

(6) Alternatives; decision process
For $27000, it seems to me there may be other ways of reducing car theft, assuming that’s the main reason for scanners. For example, we might subsidize and/or otherwise encourage the purchase of anti car theft devices. The process here was flawed, I think: first the police department went and got the money for a device, then we wondered whether we wanted the device, and whether it was the best way of doing what we want.

===
NOTE: For a page that only provides links to resources and opinions about this issue — including original press releases, grant applications, hearing videos, and the like — go here: TPPD license plate scanner.

UPDATE, 2/17: The policeman wrote in with answers. I take him at his word that images are not stored with the system and procedures he uses; that is not necessarily the case with this technology, and would need to be stipulated by Takoma Park City Council. He’s doesn’t want his emails posted on the Internet, so I won’t post them in complete form, even minus identifying information. That said, his answers to questions 1, 4 and 5 are informative:

1. Once the system is turned on, we log on and it it starts reading tags. Our system requires a training course and only those officers that have successfully completed the training are allowed to use the system. All of the officers assigned to [a particular unit with the scanners – ed.] are trained for example as are a number of others in patrol. And an officer has to get approval from our training coordinator before they are allowed to go to the training. […]

4. The system we use only list stolen cars and the list is put together by the information that DC and other jurisdictions nation wide enter into a data base of stolen vehicles. Which would include stolen vehicles used in the commission of other crimes such as homicides, armed carjacking, armed robberies, kidnapping ect. But again the system we use is directly related to stolen vehicles. We can’t just enter a vehicle into the system assign it a code and track it.

5. No. The only way to trick the scanner is to cover the tag up or remove the tag and that’s an offense in it’s self and gives me the probable cause I need to make a traffic stop. The other way would be to take a tag off a vehicle that is duly registered to another vehicle and if it’s not stolen and entered into the data base the tag reader is relying on then it doesn’t have anything to match it up to so it’s blind. But if I run that tag on my laptop and it doesn’t come back to the vehicle it’s on then I have the PC [probable cause – ed.] to make a traffic stop.

In turn:
(1) So it is always on, all plates encountered are checked without any particular reason.  I may well be in the minority in being disturbed by this; so be it.
(4) The Takoma Park grant application specifically mentions “terrorist” databases as sources for wanted plates.
(5) With respect, why would a police officer investigate a swapped license plate to discover it didn’t match the vehicle? And with respect, how would one know how her plate scanner was being defeated by a piece of electrician’s tape, or a fake license plate? The scam doesn’t necessarily need to work for long — just long enough to get the car to the chop shop, or to abandon it after use for some other purpose.

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