what will happen if the feds get warrantless access to phone location data?

TheAtlantic | On Tuesday prosecutors for the Obama administration argued that records of location data gathered by cell-phone companies should be available to law enforcement even when no search warrant has previously been issued by a judge.

In other words, If Uncle Sam wins on this argument, every law-enforcement agency in the country will be able to track your every move. More importantly, access to location data as comprehensive as that available to cell-phone carriers could allow law enforcement to determine everything from your complete social network and your your health status to how likely it is that you'll repay a loan.

The case at hand does not suggest that the Obama administration is attempting to gain this level of insight into the lives of every American citizen, but it's telling that the prosecutors seem ignorant of the power of the data they're requesting.

To understand how important location data is, especially of the variety gathered by smartphones, it's important to understand what academics have already accomplished with this data.

Sandy Pentland, a computer scientist at MIT who coined the term "reality mining" to describe the process of extracting and processing this data, put it this way in a recent essay for Edge.org:

The people who have the most valuable data are the banks, the telephone companies, the medical companies... Who you actually are is determined by where you spend time, and which things you buy... by analyzing this sort of data, scientists can tell an enormous amount about you.

In research published in 2009, Pentland and his colleagues were able to determine, for example, which students were friends based solely on mobile phone location records. Law enforcement could some day use such data to map entire criminal networks, but it could just as easily be used to visualize and contain networks of lawful protestors.

Knowing a person's location reveals their social network, which in turn reveals enormous amounts about who they are and how they are likely to behave.