In late 2014, Senate Democrats delivered to a handful of federal agencies copies of a 6,700-page classified report about the secret prison network the Central Intelligence Agency established after the Sept. 11 attacks. Senator Dianne Feinstein of California, who oversaw the report, hoped it would become a seminal document for national security professionals for generations to come. Now the report ... is at risk of remaining under wraps for more than a decade. At the Justice Department's direction, officials at the C.I.A., State Department, Pentagon and Office of the Director of National Intelligence placed their copies in safes, unread. In January 2015, Senator Richard Burr, the new chairman of the Senate Select Committee on Intelligence ... wrote to President Obama demanding that all copies be returned to the Senate. He also instructed the administration not to enter the report into the executive branch's system of records, since doing so would ... mean that the report could at some point see the light of day. On Friday, the White House informed Ms. Feinstein that it intended to preserve the report under the Presidential Records Act. That step bars the incoming administration from destroying all copies of the report. But President Obama did not ... declassify the study, which means that the report would remain secret for at least 12 years. "We can't erase our mistakes by destroying the history books," said Ms. Feinstein, who released a partly redacted summary of the report in December 2014.