Saturday, April 11, 2015

AT&T: Historical cell-phone location data provides 'detailed and intimate portrayal of the targeted person’s daily habits and work and leisure routines'

At a hearing Wednesday evening on HB 2263 by Rep. Bryan Hughes requiring warrants for the government to access personal location data from cell phone companies, cops from Dallas and Houston testified that historical information should be subject to a lower standard than a Fourth Amendment probable cause warrant because it's less accurate than real-time tracking. The argument is that you can only tell which cell tower someone connected to, further narrowed by which third of the tower's range the signal came through. They depicted the scope of a cell tower's expanse as up to ten miles, and in rural areas I suppose that could be true. But these were Dallas and Houston cops and, as a factual matter, coming from those urban jurisdictions that's some pretty weak tea.

Here's how AT&T described the accuracy of historical cell phone location data in an amicus brief on the issue in November 2014:
The precision of this location information varies according to the array of the towers and technology employed. As the density of the cell towers increases (decreasing the area covered by any particular tower), the precision of the CSLI increases correspondingly. Rural or sparsely populated areas generally have fewer cell towers, each serving a larger territory. In more densely populated areas, towers are much closer together and serve smaller areas, generating more specific location information. As customers demand more bandwidth to support smartphones, video services, and other high-volume Internet access, service providers are increasing the density of cell towers, further shrinking the size of particular cells. Service providers are also increasingly boosting their network coverage through small cells known as “microcells” or “femtocells” that may cover an area as small as a single floor of a building or an individual house.
Cellular communications technology may also generate other, more precise forms of location information. For example, some mobile devices, such as smartphones, are equipped with GPS technology which determines the device’s exact location based on signals received by the phone from a network of satellites.  In addition, because mobile devices are often in contact with more than one cell tower at a time, it is often possible to  locate the device through triangulation – i.e., determining the point of overlap among the areas covered by each of the multiple towers within range of a particular device. ...
CSLI at times may provide more sensitive and extensive personal information than the car tracking information at issue in Jones [ed. note: a SCOTUS decision declaring use of GPS trackers is a search]. Users typically keep their mobile devices with them during the entire day, potentially providing a much more extensive and continuous record of an individual’s movements and living patterns than that provided by tracking a vehicle; CSLI, therefore, is not limited to the largely public road system or to when the device user is in a vehicle. That difference, in turn, may enable officials to use historical and prospective CSLI to construct a more detailed and intimate portrayal of the targeted person’s daily habits and work and leisure routines – including activities related to the home.
If "historical data is inaccurate" is the best argument they've got (all law enforcement witnesses granted that real-time tracking should require a warrant), this bill with its 97 House authors ought to do fine!

The whole AT&T brief (pdf) is quite a remarkable document for those interested in the topic. It staked out the corporate arguments in a systematic and compelling way for installing a probable-cause warrant requirement for government to access this detailed personal information.

MORE: It's worth noting both AT&T and Verizon registered in favor of Hughes' bill at the hearing.


Anonymous said...

Grits some believe, and I agree that Stingrays have evolved to where the police can actually listen in on phone conversations. This is the legal issue--they are listening in without a warrant. We are way past the location issue which quite frankly is not such a big deal--anybody can do that.

Gritsforbreakfast said...

There are different models of Stingrays and the ones local cops are allowed to buy, as I understand it, cannot intercept phone calls. But the feds have access to ones that do.

That said, that's all second or third hand. Because of the NDAs we can't know for sure. But that's how it's been represented to me by experts I trust.

We'll have to agree to disagree that location data is "not such a big deal."

Anonymous said...

Anon @ 8:40 is absolutely right. There is no longer any distinction between the NSA, FBI and local police. Grits would be advised to watch 2 c span videos titled "Fourth Amendment and Technology" dated April 3 2015

Gritsforbreakfast said...

Here, we're talking about state and local cops and warrants in state courts. Some of the tech is similar, though not identical. But the processes are different. Hughes' bill is about regulating access to this data for the 95%+ of criminal cases in state and local courts. The Texas Lege can't control what the feds do.

Robert Langham said...

Let me state unequivocably again: No Texas LEO who gave an oath to protect and Defend the US Constitution and Bill of Rights would EVER use any technology that would restrict or violate those rights in any way. Period. To do so would invalidate their commission that they voluntarily swore an oath to obtain, correct? These folks are heroes and patriots, not just street muscle that follow any order that comes down the chain of command.

Anonymous said...

I am a contractor for all of the phone companies...cell phone service or land line. I have installed equipment that records and stores all voice and data information transmitted. Not all of the equipment operates in "real time", but all of the equipment does retain the information passed on anyone's device whether "smart phone or I-phone, wireless or landline. Stingrays can assist law enforcement with real time events for making a bust faster and efficient for their purposes but all users should be aware, that nothing transmitted is personal or private. When I have indicated to individuals that this occurs, most respond with " I don't care...I don't do anything illegal". Requiring warrants to access the data transmissions is essential in protecting our personal rights, but the technology in place can rear its head at any time and bite us all in the butt. Location data is irrelevant when the substance of a conversation or data transmission can be mined effectively once a warrant is issued and that information is provided by the suspects service provider to be used against them in a court proceeding.
Prosecutors have easier access to the information because they have easier access to funds needed to mine the information. The only saving grace is that defense attorneys and watch dogs can utilize the same process, if they are willing to pay for it, to investigate and expose the corruption and unethical practices of the opposition...of course, most know this but don't have the teeth to do it.
It's easier to make a buck selling out the client with a plea deal offered so the court machine can stay in business.