An anonymous reader sends this quote from the NY Times:
"Staking out new ground in the noisy debate about technology and privacy in law enforcement, the New Jersey Supreme Court on Thursday ordered that the police will now have to get a search warrant before obtaining tracking information from cellphone providers. The ruling (PDF) puts the state at the forefront of efforts to define the boundaries around a law enforcement practice that a national survey last year showed was routine, and typically done without court oversight or public awareness. With lower courts divided on the use of cellphone tracking data, legal experts say, the issue is likely to end up before the United States Supreme Court. The New Jersey decision also underscores the extent of the battles over government intrusion into personal data in a quickly advancing digital age, from small town police departments to the National Security Agency's surveillance of e-mail and cellphone conversations."