This is a Cato special podcast. I'm Caleb Brown. The Supreme Court today ruled that when it comes to your cell phone location data held by a third party, the cops generally need a warrant. But in a decision there was more than a hundred pages, most of those pages were devoted to dissents, differing ideas about the reasonable expectation of privacy, property interests in your data, and more.

Cato's Ilia Shapiro and Julian Sanchez break down the ruling of Carpenter, the United States.

There were a string of robberies in the Toledo area and police arrested someone.

There was a confession and they began to suspect certain other people, but either they

didn't have probable cause or in any event they did not seek a warrant.

What they did though was ask various cell phone companies for data on the

location of various cell phones that were then traced to their owners. And based on that they found

that the cell phones were pinging off towers in the general area of the

stores, cell phone stores, ironically, that had been robbed and so arrested the people who were

the owners of those cell phones and ultimately got convictions and Mr. Carpenter challenged

his conviction on the ground that the police conducted a search of his data

improperly.

They needed a warrant and this is what went up to the Supreme Court which

decided five to four that indeed this was a violation of the fourth amendment

extending somewhat the reasonable expectation of privacy tests that's been around for more than 50 years now

That you don't give up your privacy when even a third party has some of that data at least in this context when we're talking about cell phone

location data the court was very cautious John Roberts the chief justice

wrote the majority opinion joined by the the four Democratic

appointees saying we're not setting new doctrine.

This is a narrow ruling doesn't affect other technologies, doesn't affect

national security related investigations, but at least in the context of cell phone data,

you maintain a privacy interest in that and the police need a warrant.

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