"The American Civil Liberties Union was curious about warrantless government snooping on citizens’ text messages. So the group filed a Freedom of Information Act request to the Justice Department. 
Here’s what they got back: A memo header:  “Guidance for the Minimization of Text Messages over Dual-Function Cellular Telephones” and then 15 pages, completely blacked out.” 
Source

"The American Civil Liberties Union was curious about warrantless government snooping on citizens’ text messages. So the group filed a Freedom of Information Act request to the Justice Department. 

Here’s what they got backA memo header:  “Guidance for the Minimization of Text Messages over Dual-Function Cellular Telephones” and then 15 pages, completely blacked out.” 

Source