600 Billion Data Points Per Day? It’s Time to Restore the Fourth Amendment

by on August 17, 2009 · 17 comments

Jeff Jonas has published an important post: “Your Movements Speak for Themselves: Space-Time Travel Data is Analytic Super-Food!”

More than you probably realize, your mobile device is a digital sensor, creating records of your whereabouts and movements:

Mobile devices in America are generating something like 600 billion geo-spatially tagged transactions per day. Every call, text message, email and data transfer handled by your mobile device creates a transaction with your space-time coordinate (to roughly 60 meters accuracy if there are three cell towers in range), whether you have GPS or not. Got a Blackberry? Every few minutes, it sends a heartbeat, creating a transaction whether you are using the phone or not. If the device is GPS-enabled and you’re using a location-based service your location is accurate to somewhere between 10 and 30 meters. Using Wi-Fi? It is accurate below 10 meters.

The process of deploying this data to markedly improve our lives is underway. A friend of Jonas’ says that space-time travel data used to reveal traffic tie-ups shaves two to four hours off his commute each week. When it is put to full use, “the world we live in will fundamentally change. Organizations and citizens alike will operate with substantially more efficiency. There will be less carbon emissions, increased longevity, and fewer deaths.”

This progress is not without cost:


A government not so keen on free speech could use such data to see a crowd converging towards a protest site and respond before the swarm takes form — detected and preempted, this protest never happens. Or worse, it could be used to understand and then undermine any political opponent.

Very few want government to be able to use this data as Jonas describes, and not everybody wants to participate in the information economy quite so robustly. But the public can’t protect itself against what it can’t see. So Jonas invites holders of space-time data to reveal it:

[O]ne way to enlighten the consumer would involve holders of space-time-travel data [permitting] an owner of a mobile device the ability to also see what they can see:

(a) The top 10 places you spend the most time (e.g., 1. a home address, 2. a work address, 3. a secondary work facility address, 4. your kids school address, 5. your gym address, and so on);

(b) The top three most predictable places you will be at a specific time when on the move (e.g., Vegas on the 215 freeway passing the Rainbow exit on Thursdays 6:07 – 6:21pm — 57% of the time);

(c) The first name and first letter of the last name of the top 20 people that you regularly meet-up with (turns out to be wife, kids, best friends, and co-workers – and hopefully in that order!)

(d) The best three predictions of where you will be for more than one hour (in one place) over the next month, not counting home or work.

Google’s Android and Latitude products are candidates to take the lead, he says, and I agree. Google collectively understands both openness and privacy, and it’s nimble enough still to execute something like this. Other mobile providers would be forced to follow this innovation.

What should we do to reap the benefits while minimizing the costs? The starting point is you: It is your responsibility to deal with your mobile provider as an adult. Have you read your contract? Have you asked them whether they collect this data, how long they keep it, whether they share it, and under what terms?

Think about how you can obscure yourself. Put your phone in airplane mode when you are going someplace unusual – or someplace usual. (You might find that taking a break from being connected opens new vistas in front of your eyes.) Trade phones with others from time to time. There are probably hacks on mobile phone system that could allow people to protect themselves to some degree.

Privacy self-help is important, but obviously it can be costly. And you shouldn’t have to obscure yourself from your mobile communications provider, giving up the benefits of connected living, to maintain your privacy from government.

The emergence of space-time travel data begs for restoration of Fourth Amendment protections in communications data. In my American University Law Review article, “Reforming Fourth Amendment Privacy Doctrine,” I described the sorry state of the Fourth Amendment as to modern communications.

The “reasonable expectation of privacy” doctrine that arose out of the Supreme Court’s 1967 Katz decision is wrong—it isn’t even founded in the majority holding of the case. The “third-party doctrine,” following Katz in a pair of early 1970s Bank Secrecy Act cases, denies individuals Fourth Amendment claims on information held by service providers. Smith v. Maryland brought it home to communications in 1979, holding that people do not have a “reasonable expectation of privacy” in the telephone numbers they dial. (Nevermind that they actually have privacy—the doctrine trumps it.)

Concluding, apropos of Jonas’ post, I wrote:

These holdings were never right, but they grow more wrong with each step forward in modern, connected living. Incredibly deep reservoirs of information are constantly collected by third-party service providers today.

Cellular telephone networks pinpoint customers’ locations throughout the day through the movement of their phones. Internet service providers maintain copies of huge swaths of the information that crosses their networks, tied to customer identifiers. Search engines maintain logs of searches that can be correlated to specific computers and usually the individuals that use them. Payment systems record each instance of commerce, and the time and place it occurred.

The totality of these records are very, very revealing of people’s lives. They are a window onto each individual’s spiritual nature, feelings, and intellect. They reflect each American’s beliefs, thoughts, emotions, and sensations. They ought to be protected, as they are the modern iteration of our “papers and effects.”

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