The Obama administration secretly won permission from a surveillance court in 2011 to reverse restrictions on the National Security Agency’s use of intercepted phone calls and e-mails, permitting the agency to search deliberately for Americans’ communications in its massive databases, according to interviews with government officials and recently declassified material. In addition, the court extended the length of time that the NSA is allowed to retain intercepted U.S. communications from five years to six years — and more under special circumstances, according to the documents, which include a recently released 2011 opinion by U.S. District Judge John D. Bates, then...