Court Says It’s OK to Track Cell Phones Without a Warrant

Over at a public defender, Gideon is talking about a disturbing new ruling from the 6th Circuit:

Law enforcement and cops have been using cell tower data to pinpoint the location of a cell phone (and by extension its user) for a few years now, but this was mostly done post-hoc, to prove that a particular individual was at a particular location at the time of the crime. I’m also fairly certain that prosecutors and cops have been getting warrants to track cell phones in order to locate an individual they are chasing.

But can all of this be done without a warrant? Is there a reasonable expectation of privacy in the location signal of your phone? Is this something that society today is prepared to accept? That one doesn’t generally expect someone to know where you are based on the contact your cellphone has (covertly and unbeknownst to you) with a cell phone tower and the cell phone company?

That’s what the 6th Circuit just said in a decision [PDF] released two days ago: that there is no reasonable expectation of privacy in that information and thus, no need to get a warrant in order to conduct surveillance.

I didn’t realize it at first, but on reflection, that’s one of the most frightening anti-privacy decisions I’ve ever heard about, because it’s about data. I mean, sure it’s a bad thing that cops can, for example, stop and frisk people for no good reason, but at least stop-and-frisk is limited by the supply of police officers. No such limits apply to location queries on the cellular networks: If they can track one of us without a warrant, then there’s nothing to stop them from tracking all of us.

(Don’t fall for the claim that there would be “too much data” to track us all. That’s a familiar argument, and it’s wrong. We live in an age of cheap and ubiquitous computing. You can rent a cloud of processors with a credit card, and fault-tolerant distributed database software for problems of this size is available for free.)

The court basically said that following a cell phone is no different than using a dog to track someone’s scent, so no warrant is necessary. Gideon quotes the Cato Institute’s response to that:

But it does not follow at all. “What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection,” the Supreme Court explained in the seminal case of Katz v. United States, “But what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected.” Any member of the public can buy a dog and follow a scent. Any member of the public can view and copy down a license plate number. Any member of the public can view the external paint job of a car. But any member of the public cannot just track the GPS signal of a random cell phone–and if they could, most of us would be extremely wary about carrying cell phones. Unlike all these other examples, GPS tracking as employed here depends crucially on the ability of police to invoke state authority–a seemingly salient distinction the court fails to take any note of.

That’s a good explanation of my own objection to these kinds of searches. A lot of recent weakening of our 4th Amendment rights has been justified on the grounds that we have no expectation of privacy in information that we store with third parties. But it’s the government that is using its unique powers to force those third parties to turn over that information. And when the government uses those powers, it seems to me that should trigger Constitutional protections. That’s why we have rights; to limit government power over us.

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