Posts Tagged ‘pen register’

Cell Site Data — Is a Warrant Really Required?

Monday, March 23rd, 2009


The 3rd Circuit is hearing an interesting appeal on whether the government needs to get a warrant before demanding cell site data from phone companies.

Cell sites are those transmitters you see on rooftops and towers, beaming and receiving cell phone communications. Their range varies from a few blocks to a circle twenty miles across, depending on their power and local geography. When a cell phone is being used, it’s communicating with a particular cell site.

Phone company records will show what cell site was being used by a particular phone at any given time. Law enforcement often requests such records, to help narrow down possible locations for an individual using a phone. This can be particularly useful if the individual is in motion, because his signal will be picked up by a series of cell sites, which can be used to map his progress.

This is passive data, as opposed to an active “ping” whereby a signal is sent directly to a particular phone for the purpose of identifying its location.

Most phone companies will not provide real-time cell site data to law enforcement without a court order. So court orders are routinely sought, often in conjunction with pen registers (calling records which show the time and phone number for calls sent and received). 18 U.S.C. § 2703 permits such an order when there are “specific and articulable facts showing that there are reasonable grounds to believe that… the records… are relevant and material to an ongoing criminal investigation.” These are called 2703(d) orders, and are different from eavesdropping warrants requiring probable cause.

In this case, the feds asked for a 2703(d) order, but unusually did not seek real-time cell site info. Instead, they asked for an order permitting them to get historical data. They’d been investigating drug trafficking, and were tracking one subject’s phones already. During the investigation, they identified what they believed to be the phone of their subject’s supplier. Physical surveillance proving difficult, the feds wanted to see historical cell site data, to see if they could figure out how the supplier had moved around.

The magistrate denied that request, holding that a request for real-time data would have been fine, but that historical data is not permitted pursuant to a 2703(d) order.

(As an aside, the investigators learned of the supplier’s number in June 2007, but didn’t apply for the historical data until February 2008. We know the feds take an inordinate amount of time in their wire and pen applications — one reason why they do comparatively few of them — but eight or nine months is astonishing.)

The feds appealed to the district court, arguing that the magistrate’s decision was bizarre. Instead, however, the district court went further than the magistrate had, and ruled that a warrant based on probable cause would be required for such historical records.

Although we are on the defense side, it seems as though both the magistrate and the district court judge got things backwards. Real-time cell site data, one would expect, is significantly more intrusive of privacy than historical data from up to six months ago. Real-time data can be used to locate where a person is now. The law clearly permits this more invasive search to be performed with a mere order. To require a probable cause warrant for the clearly less-invasive search makes little sense.

The ACLU, meanwhile, has stepped in with an amicus brief opposing the government. They basically argue that, yes, a 2703(d) order would have been sufficient, but the magistrate had the discretion to require a probable cause warrant instead. They then argue that, no, a 2703(d) order would not have been sufficient, and in fact a probable cause warrant ought to be required for all cell site information. People don’t know their cell site data is being collected, so they have an expectation of privacy.

We’re frankly not thrilled with the quality of either side’s brief. But the ACLU wins the “silliest syllogism” award for this one: They hypothesize a subject named Bob. Bob is talking on his cell phone as he enters his office, so with real-time cell site info the police now know he’s in his office. Bob is surveilled to his house. Once inside his house, he makes another call. But without the cell-site info, the cops would have no reason to believe the cell phone never left Bob’s office. Riiiight.

This is a case of first impression in the Third Circuit. One could easily see them ruling against the feds, too.

Feds who, by the way, brought this on themselves.

Seriously. They could have simply subpoenaed the historical business records without going to a judge in the first place. Asking permission to do something novel is the best way to create a precedent saying you can’t do it. But subpoenaing already-existing business records from phone companies is strictly routine. If they’d done it that way, we’d wager that the court would even have compelled the phone company to comply, if the need arose.