The Wall Street Journal reported that Apple’s iPhones and iPads and Google’s Android mobile phones all collect and transmit back to the companies data about a device’s nearby WiFi access points, geo-location data, and in Google’s case, a unique identifier. This raises serious privacy concerns regarding the ease with which law enforcement agencies can access this sensitive data. The primary law in the US that governs the privacy of information kept by Internet and communications companies is the Electronic Communications Privacy Act (ECPA) This law dates back to 1986, long before cloud computing, email inboxes larger than 5 megabytes, or GPS enabled smartphones.”]
Source: http://paranoia.dubfire.net/2011/04/how-can-us-law-enforcement-agencies.html