“Most Americans carry cellphones, but many may not know that government agencies can track their movements through the signals emanating from the handset.

In recent years, law enforcement officials have turned to cellular technology as a tool for easily and secretly monitoring the movements of suspects as they occur. But this kind of surveillance – which investigators have been able to conduct with easily obtained court orders – has now come under tougher legal scrutiny.

In the last four months, three federal judges have denied prosecutors the right to get cellphone tracking information from wireless companies without first showing “probable cause” to believe that a crime has been or is being committed. That is the same standard applied to requests for search warrants.” [continued]

NYT – Live Tracking of Mobile Phones Prompts Court Fights on Privacy