The Obama administration has been quietly advising local police not to disclose details about surveillance technology they are using to sweep up basic cellphone data from entire neighborhoods. Citing security reasons, the U.S. has intervened in routine state public records cases and criminal trials regarding use of the technology. This has resulted in police departments withholding materials or heavily censoring documents in rare instances when they disclose any [information] about the purchase and use of such powerful surveillance equipment. One well-known type of this surveillance equipment is known as a Stingray. The equipment tricks cellphones into identifying some of their owners' account information, like a unique subscriber number, and transmitting data to police as if it were a phone company's tower. That allows police to obtain cellphone information without having to ask for help from service providers ... and can locate a phone without the user even making a call or sending a text message. The Obama administration is asking agencies to withhold common information about the equipment, such as how the technology is used and how to turn it on. These extreme secrecy efforts are in relation to very controversial, local government surveillance practices using highly invasive technology," said Nathan Freed Wessler, a staff attorney with the American Civil Liberties Union, which has fought for the release of these types of records. "People should have the facts about what the government is doing to them."