Police use of technology to locate and track criminal suspects has drawn increasing attention from courts, commentators, and the public. In United States v. Jones, the Supreme Court held that police installation of a GPS tracking device on a suspect’s vehicle constituted a search under the Fourth Amendment. Less attention has been paid to police tracking of cell phones—a far more common practice. Police can now locate a cell phone within several feet, using either GPS or information taken from cell towers.

In August 2011, the government asked a federal magistrate judge in Maryland to allow thirty days of cell phone GPS tracking to aid in the apprehension of the subject of an arrest warrant. The judge denied the application, ruling that precise tracking for any period would be a search, and that an arrest warrant did not make the search reasonable under Payton v. New York, which allows officers to arrest the subject of an arrest warrant in his home if the officers reasonably believe he is present.

This Note examines the magistrate judge’s opinion, considers critical commentary, and analyzes a 2006 district court case holding that imprecise tracking to aid apprehension was constitutional. Cell phone tracking raises different issues than the vehicular GPS considered in Jones. Cell phone tracking does not involve a physical trespass, but it does follow individuals into private spaces. The Note concludes that precise cell phone tracking is a search and argues that such a search could be reasonable under Payton, but only if carefully limited. While cell phone tracking to aid arrest increases public safety by helping police arrest criminal suspects quickly and efficiently, it should not be used to find evidence of crime. Judges should only allow tracking for one or two days to ensure that police quickly apprehend subjects of arrest warrants, conduct unauthorized investigations.