WASHINGTON — A Senate security officer stepped out of the December chill last year and delivered envelopes marked “Top Secret” to the Pentagon, the C.I.A., the State Department and the Justice Department. Inside each packet was a disc containing a 6,700-page classified report on the C.I.A.’s secret prison program and a letter from Senator Dianne Feinstein, urging officials to read the report to ensure that the lessons were not lost to time.

Today, those discs sit untouched in vaults across Washington, still in their original envelopes. The F.B.I. has not retrieved a copy held for it in the Justice Department’s safe. State Department officials, who locked up their copy and marked it “Congressional Record — Do Not Open, Do Not Access” as soon as it arrived, have not read it either.

Nearly a year after the Senate released a declassified 500-page summary of the report, the fate of the entire document remains in limbo, the subject of battles in the courts and in Congress. Until those disputes are resolved, the Justice Department has prohibited officials from the government agencies that possess it from even opening the report, effectively keeping the people in charge of America’s counterterrorism future from reading about its past. There is also the possibility that the documents could remain locked in a Senate vault for good.

In a letter to Attorney General Loretta E. Lynch last week, Ms. Feinstein, a California Democrat, said the Justice Department was preventing the government from “learning from the mistakes of the past to ensure that they are not repeated.”