Your cell phone's a snitch

In the winter of 2010, there was a robbery in Detroit. Two men rush into a Radio Shack on Jefferson Avenue carrying a handgun, and demand smartphones, enough smartphones to fill laundry bags. Then they flee. A few days later, they do it again at a T-Mobile store. And a few months after that, another robbery. They are criminals that need to be stopped.

Police try to gather every bit of evidence they can use to catch the robbers and make the case stick.

By the time Timothy Carpenter is facing robbery charges, the FBI already has a trove of data on him. Enough data to piece together an intimate portrait of his life. They could tell where he went and when, which Sundays he skipped out on church, and which nights he decided to sleep somewhere other than his own house.

They could also tell he was near a Radio Shack in Detroit just about the time it was held up by two armed men.

Authorities had this information because they had Carpenter's cell phone number. Police asked Carpenter's cell phone carrier to turn over 200 spreadsheets detailing where his phone was at the beginning and end of every call for four months straight. They didn't even need a warrant. That's how it works. Each major cell phone carrier gets tens of thousands of requests like this one from law enforcement every year.

For Tim Carpenter, this information helped land him in prison for 116 years.

But should police be able to get that level of intimate data so easily? That's the question before The Supreme Court right now.

Today on the show, the story of Tim Carpenter, his cell phone, and the court battle it sparked.

The government says this kind of data helps fight crime and stop criminals like Carpenter. They say it's like old fashioned police work — tailing someone or staking out a suspect's home — adapted for the digital age. Carpenter's attorneys argue that this is a whole new level of surveillance, seizing this data without a warrant is a violation of the 4th amendment, which protects against illegal searches and seizures. They say this has huge stakes: Everyone is walking around with a spy in their pocket, gathering data on the intimate details of our lives. The police shouldn't be able to get that data so easily.

The case could reach well beyond cell phone location records — and affect what kind of privacy we can expect for all the footprints we leave behind in the digital age.

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