Can the police get your cellphone location data without a warrant?

It's a case that's been winding through the courts for years. Now, the U.S. Supreme Court is set to hear Carpenter v. United States. Its decision will have a major impact on how police in the U.S. can access phone metadata.

The story goes back to a string of armed robberies at Radio Shack and T-Mobile stores in 2010 and 2011. Timothy Carpenter was convicted of six counts of robbery.

Police had accessed what's known as cell site location information records. They used that data to put Carpenter at the time and approximate locations that the robberies occurred.

Whenever you make or receive a phone call or text message, or even just have an app running in the background, your phone connects to cell towers in your area.

And records of when and where those connections happened are retained by phone companies.

In this case, the police requested data regarding Carpenter's phone from several service providers.

The cell companies turned over the data, without the police needing a warrant. It's important to note that this is metadata about the phone's activity, as opposed to the content of phone calls or texts.

Jennifer Lynch is a senior staff attorney at the Electronic Frontier Foundation. "This case is addressing whether the Fourth Amendment requires the government to seek a warrant before accessing cell site location information," she says.

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.- Fourth Amendment, U.S. Constitution

"This is one of a number of cases across the United States that are addressing this same exact issue," she explains.

In this case "what the defense has argued is that the data is very sensitive. It provides a pretty robust picture of everywhere you go in your life," she says.

Conversely, Jennifer explains, the government argues that it's not particularly sensitive. Furthermore, this type of metadata is information that's shared with the cell phone company. Cases from the late 1970s, looked at this question of privacy and the metadata shared with a service provider.  

We're at a point where the data collected is much more granular and specific- Jennifer Lynch

"One case in particular, Smith v. Maryland, looked at the numbers dialed...and the Supreme Court, in a very deeply divided opinion, held that because the numbers you dial on your phone are shared with...the phone company, you don't have a privacy interest that's protectable," she says.

She argues that today's cellphone era is very different. "We're at a point where the data collected is much more granular and specific...In Smith, it was one landline phone in one location, and the phone numbers dialed over a matter of days, and in Mr. Carpenter's case, we're talking about the cellphone that he keeps on his person at all times, pretty much, and five months of data."

Here in Canada, the situation is different. Steven Penney is a professor in the Faculty of Law at the University of Alberta. He specializes in criminal procedure, evidence, and law and technology.

"Under section 8 of the Charter of Rights and Freedoms, which protects all of our rights against unreasonable search and seizure, the collection of metadata in the telecommunications field...has been considered by our courts to attract the protection of section 8," he explains.

"It engages what we call a 'reasonable expectation of privacy', and up until this Carpenter case, the U.S. Supreme Court has held that in similar situations in the U.S., that information is not protected," Steven says. Section 8 is roughly equivalent to the Fourth Amendment in the U.S.

There have been cases in Canada where this issue has come up. "Some of those cases stand for the proposition that this information is protected," Steven explains. "In order to obtain it, the police have to engage in a reasonable search, and that will in almost all circumstances require them to get some kind of warrant or production order."

It would have involved the revealing and disclosure of metadata of thousands and thousands of potential customers.- Steven Penney

Steven cites one decision by the Ontario Superior Court where a police service requested a large metadata dump from Telus' and Rogers' cell towers. "The judge in that case found that the request was grossly overbroad," Steven says.

"It would have involved the revealing and disclosure of metadata of thousands and thousands of potential customers, most of whom, obviously, would have had nothing to do with the investigation."

Steven thinks that sends a strong message. "Not only is this information protected by our Charter, but that any request to obtain a warrant is going to have to be narrowly tailored to avoid that kind of overbreadth," he argues.