License Plate Scanners Logging Our Every Move

Eugen Leitl eugen at
Wed Nov 23 06:01:09 PST 2011

License Plate Scanners Logging Our Every Move

The Washington Post reported on Sunday that the District of Columbia is
engaging in widespread tracking of citizenbs movements using automated
license plate readers (ALPRs). According to the Post, the D.C. police:

    Are running more than one ALPR per square mile;

    Are planning on sharply increasing the density of these devices until
they form a bcomprehensive dragnet;b

    Retain the time/date/location/tag number even of innocent people for whom
nothing is found to be wrong;

    Store that data in a database for three years. 

It has now become clear that this technology, if we do not limit its use,
will represent a significant step toward the creation of a surveillance
society in the United States.

The first we heard of this technology was in a March 2002 piece in The Boston
Globe with the headline bParking Enforcement on a Roll.b At that time, the
technology was being deployed to scan parking lots for licenses associated
with unpaid parking tickets and other fines. As we said at the time as we
began to get questions about the technology, we donbt have any fundamental
objections to the technology itself b after all, a police officer could
manually phone in all the tags in a parking lot to check for unpaid tickets,
and this just did the same thing in a quicker, more efficient way. Sometimes
the speed and efficiency of computers does fundamentally change the nature of
surveillance compared to non-computerized equivalents b as with GPS tracking,
for example. Quantity can change quality. But checking for unpaid tickets and
stolen cars does not affect the innocent, so this did not seem to us to be a
problem b as long, we said, as the police do not retain location data about
innocent people where nothing is found to be wrong.

Our main concern was that the technology not grow into a means for the
constant, routine tracking of Americans and their whereabouts.  Sometimes
when we say things like that, webre accused of being paranoid. But I am
always amazed by the speed and consistency with which our worst fears for
these kinds of technologies turn into reality.

Clearly this technology is rapidly approaching the point where it could be
used to reconstruct the entire movements of any individual vehicle. As we
have argued in the context of GPS tracking (and as I said to the Post
reporter) that level of intrusion on private life is something that the
police should not be able to engage in without a warrant.

The Post article cites a number of examples in which the technology has
proven useful to police. Of course, if the police track all of us all the
time, there is no doubt that will help to solve some crimes b just as it
would no doubt help solve some crimes if they could read everybodybs e-mail
and install cameras in everybodybs homes. But in a free society, we donbt let
the police watch over us just because we might do something wrong. That is
not the balance struck by our Constitution and is not the balance we should
strike in our policymaking.

Finally, technologies that have such significant implications for our privacy
b and more broadly, what kind of society we want to live in b should not be
put in place through what I call bprocurement policymaking.b The police
should not be able to run out and buy a new technology and put it in place
before anybody realizes whatbs going on b before society has a chance to
discuss and debate it and consider where we want to draw the lines between
police power and the freedom to live a private life. That decision is one
that should be made through the full, open, democratic process b not quietly
and unilaterally by police departments.

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