Catherine Crump: The small and surprisingly dangerous detail the police track about you

The shocking police crackdown on protestors in Ferguson, Missouri,

in the wake of the police shooting of Michael Brown,

underscored the extent to which advanced military weapons and equipment,

designed for the battlefield,

are making their way

to small-town police departments across the United States.

Although much tougher to observe,

this same thing is happening with surveillance equipment.

NSA-style mass surveillance is enabling

local police departments to gather vast quantities

of sensitive information about each and every one of us

in a way that was never previously possible.

Location information can be very sensitive.

If you drive your car around the United States,

it can reveal if you go to a therapist,

attend an Alcoholics Anonymous meeting,

if you go to church or if you don't go to church.

And when that information about you

is combined with the same information about everyone else,

the government can gain a detailed portrait

of how private citizens interact.

This information used to be private.

Thanks to modern technology,

the government knows far too much about what happens behind closed doors.

And local police departments make decisions about who they think you are

based on this information.

One of the key technologies driving mass location tracking

is the innocuous-sounding Automatic License Plate Reader.

If you haven't seen one,

it's probably because you didn't know what to look for --

they're everywhere.

Mounted on roads or on police cars,

Automatic License Plate Readers capture images of every passing car

and convert the license plate into machine-readable text

so that they can be checked against hot lists

of cars potentially wanted for wrongdoing.

But more than that, increasingly,

local police departments are keeping records

not just of people wanted for wrongdoing,

but of every plate that passes them by,

resulting in the collection of mass quantities of data

about where Americans have gone.

Did you know this was happening?

When Mike Katz-Lacabe asked his local police department

for information about the plate reader data they had on him,

this is what they got:

in addition to the date, time and location,

the police department had photographs that captured

where he was going and often who he was with.

The second photo from the top is a picture of Mike and his two daughters

getting out of their car in their own driveway.

The government has hundreds of photos like this

about Mike going about his daily life.

And if you drive a car in the United States,

I would bet money that they have photographs

like this of you going about your daily life.

Mike hasn't done anything wrong.

Why is it okay that the government is keeping all of this information?

The reason it's happening is because,

as the cost of storing this data has plummeted,

the police departments simply hang on to it,

just in case it could be useful someday.

The issue is not just that one police department

is gathering this information in isolation

or even that multiple police departments are doing it.

At the same time, the federal government

is collecting all of these individual pots of data,

and pooling them together into one vast database

with hundreds of millions of hits,

showing where Americans have traveled.

This document from the Federal Drug Enforcement Administration,

which is one of the agencies primarily interested in this,

is one of several that reveal the existence of this database.

Meanwhile, in New York City,

the NYPD has driven police cars equipped with license plate readers

past mosques in order to figure out who is attending.

The uses and abuses of this technology aren't limited to the United States.

In the U.K., the police department

put 80-year-old John Kat on a plate reader watch list

after he had attended dozens of lawful political demonstrations

where he liked to sit on a bench and sketch the attendees.

License plate readers aren't the only mass location tracking technology

available to law enforcement agents today.

Through a technique known as a cell tower dump,

law enforcement agents can uncover who was using

one or more cell towers at a particular time,

a technique which has been known to reveal

the location of tens of thousands and even hundreds of thousands of people.

Also, using a device known as a StingRay,

law enforcement agents can send tracking signals

inside people's houses to identify the cell phones located there.

And if they don't know which house to target,

they've been known to drive this technology

around through whole neighborhoods.

Just as the police in Ferguson possess high-tech military weapons and equipment,

so too do police departments across the United States

possess high-tech surveillance gear.

Just because you don't see it,

doesn't mean it's not there.

The question is, what should we do about this?

I think this poses a serious civil liberties threat.

History has shown that once the police have massive quantities of data,

tracking the movements of innocent people,

it gets abused, maybe for blackmail, maybe for political advantage,

or maybe for simple voyeurism.

Fortunately, there are steps we can take.

Local police departments can be governed by the city councils,

which can pass laws requiring the police

to dispose of the data about innocent people

while allowing the legitimate uses of the technology to go forward.

Thank you.

(Applause).