Think of the things you can do with a smartphone. You can check your e-mail. You can Web surf. You can watch videos, play games and use lifestyle apps such as calorie counters. You can placate a fretful child in the doctor’s office waiting room with apps for kids. You can take photos, stay in touch with friends via social media and even order a taxi or a pizza.

But that’s not where the benefits of smartphones stop. If you’re a member of law enforcement, you can keep track of suspects, at least under some circumstances. This isn’t a benefit that gets advertised in the window of shops that sell smartphones, however.

Once upon a time, keeping track of a suspect was a hassle for police. It was expensive: it involved lots of overtime and (as multiple “Law & Order” episodes have shown us), a lot of boring time sitting in a car outside a suspect’s house downing coffee by the gallon. But thanks to the GPS tracking capability of the average cell phone, keeping tabs on suspects goes from being an endeavor that might costs tens of thousands of dollars and brings the cost to just a few dollars.

In a recent paper published in the Yale Law Journal, authors Kevin S. Bankston and Ashkan Soltani, note that this is a real problem, both in light of Fourth Amendment rights against unreasonable search and seizure, and a recent Supreme Court decision, United States v Jones, that found that warrantless government surveillance of an individual’s public movements for 28 days using a GPS device violated a reasonable expectation of privacy and constituted a Fourth Amendment search.

According to the paper, it’s the ease with which cops can keep tabs on someone with GPS that makes it so problematic.

image via shutterstock 

“The simple idea is that structural constraints—physical and technological barriers—make certain conduct costly, sometimes impossibly costly,” wrote the paper’s authors. “These costs act as non-legal regulations, essentially providing a non-legal ‘right’ against the behaviors they prevent.”

In other words, physical surveillance using lots of manpower is simply too expensive to use on anyone but suspects of extremely egregious crimes. With GPS technology, it’s cost-effective to track nearly anyone. And because modern technology makes surveillance easy and cheap, it may be necessary to tighten Fourth Amendment restrictions, something that United States v Jones did not clearly do.

“A central shortcoming of Justice Alito’s [writing for the majority in U.S. v Jones] opinion is that it hinges on the ever-decreasing cost of prolonged location tracking, but never supports its reasoning with data,” according to the authors. “It doesn’t specifically describe or compare the cost of prolonged tracking done with and without GPS technology. Nor does the opinion use any data to elaborate on how great a cost difference between prolonged tracking before and after the introduction of GPS technology would justify an equilibrium-adjusting increase in Fourth Amendment protection. If the opinion had ‘shown its work,’ other courts could emulate and apply it.”

This lack of clarity may leave many enforcement departments scratching their heads, and it will mostly certainly lead to more time in the courtroom sorting it all out.