U.S. Congressman Edward Markey (D-Mass.) wants cellphone carriers to disclose their role in helping police departments track suspects and conduct investigations, reports the New York Times.
In a letter to the carriers, Rep. Markey said he is "deeply concerned" that routine tracking of cellphone use may violate the privacy rights of Americans.
The issue received renewed public attention after a Supreme Court ruling in January finding that police use of a GPS device on a drug suspect's car without a warrant violated his Fourth Amendment rights.