Yale Law Journal

The monetary cost to law enforcement to track people has taken a nosedive following the broad adoption of cell phones, putting a dollar figure to the practice. Or to be more precise, a cents figure.

Tracking a suspect using their cell phone's Global Positioning System (GPS) costs around 1/1000th of what it costs to track them using the visual surveillance method, according to a new study published in the Yale Law Journal on Thursday by privacy researchers Kevin Bankston and Ashkan Soltani.

The cost of nonstop surveillance has been reduced from an average of $275 an hour for a five-car "surveillance box" to less than a few dollars per hour, depending on which cell phone carrier the suspect uses. Sprint, for example, is significantly cheaper at 4 cents per hour for 28 days of surveillance than AT&T ($1.19) or even T-Mobile ($4.17).

The goal of the research was not to prove what many already suspected, the researchers wrote, but to demonstrate that cell phone and GPS surveillance represent such a dramatic shift in the technology used to track suspects that it represents a "radical shift in police power." That shift indicates that cost can be a "powerful yardstick" in evaluating the privacy impact of technology.

Yale Law Journal

"For now, our modest hope is to inspire an enterprising criminal defense attorney to articulate cost-based arguments when moving to suppress GPS or cell tracking data," they said. "Our less modest hope is to see that motion granted."

But truly, there's more to it than a mere legal argument. The researchers juxtaposed their research against the Supreme Court's decision in 2012's US v. Jones, a landmark surveillance and Fourth Amendment privacy rights case, to show that technological and cost changes in tracking can require an entirely different legal standard. Without a tougher standard, they argue, technologically-advanced surveillance techniques run the risk of running roughshod over privacy rights.

Given the revelations contained in the document leaked by former NSA contractor Edward Snowden, one could argue they already have.