The past fifty years has witnessed an evolution in technology advancement in police surveillance. Today, one of the essential tools of police surveillance is something most Americans carry with them in their pockets every day, the cell phone. Cell phones not only contain a huge repository of personal data, they also provide continuous surveillance of a person’s movement known as cell site location information (CSLI).

In 1986, Congress sought to provide some privacy protections to CSLI in the Stored Communication Act. Although this solution may have struck the proper balance in an age when cell phones were a mere novelty in the hands of a comparative few, we now live in an age where, as the U.S. Supreme Court recently recognized, cell phones could be seen “an important feature of human anatomy.” In 1986, there were only an estimated 681,825 subscribers serviced by 1531, cell sites. By 2013, there were 335 million subscribers and over 340,000 cell sites.

Recently, cell phone service providers have begun to use small cell technologies, miniature cell phone towers that can provide additional coverage and bandwidth support to overburdened cellular networks. Small cells, known variously as femtocells, picocells, and microcells, are already installed throughout the United States, in particular in urban areas. As small cells overtake traditional cell phone towers as the most common means of transmitting cellular signals, CSLI will transform from a means of placing a person’s phone in a general area within a matter of miles to a precise location tracking tool charting a person’s movements down to a matter of feet.

The late Justice Scalia in his 2001 majority opinion in Kyllo v. U.S., a case involving thermal imaging, opined that “while the technology used in the present case was relatively crude, the rule we adopt must take account of more sophisticated systems that are already in use or in development.”

This Article explores the evolution of CSLI by focusing on the rise of small cell technologies. It also canvasses decisions in the circuits involving CSLI. It points out that the third-party exception to the Fourth Amendment is inapplicable to CSLI. Following Justice Scalia’s admonition, we believe that CSLI will only grow more precise as small cells infiltrate cellular networks and we therefore adopt an approach that incorporates the Fourth Amendment requirements for a search warrant particularly describing the place to be searched and items to be seized as well as the requirement for probable cause. Placing CSLI under the Fourth Amendment would make a major section of the Stored Communication Act unconstitutional.