The study, to be released Monday, corroborates the findings of a White House-appointed review group, which said last month that the NSA counterterrorism program “was not essential to preventing attacks” and that much of the evidence it did turn up “could readily have been obtained in a timely manner using conventional [court] orders.”…

The researchers at the New America Foundation found that the program provided evidence to initiate only one case, involving a San Diego cabdriver, Basaaly ­Moalin, who was convicted of sending money to a terrorist group in Somalia. Three co-conspirators were also convicted. The cases involved no threat of attack against the United States.

“The overall problem for U.S. counterterrorism officials is not that they need vaster amounts of information from the bulk surveillance programs, but that they don’t sufficiently understand or widely share the information they already possess that was derived from conventional law enforcement and intelligence techniques,” said the report, whose principal author is Peter Bergen, director of the foundation’s National Security Program and an expert on terrorism.

In at least 48 instances, traditional surveillance warrants obtained from the Foreign Intelligence Surveillance Court were used to obtain evidence through intercepts of phone calls and e-mails, said the researchers, whose results are in an online database.