As America marked the 50th anniversary of US president John F. Kennedy’s assassination four years ago, a clear majority of Americans (according to polls by Gallup and AP/GfK) still believed that the whole truth of what happened in Dallas on November 22, 1963 remains unknown: That Lee Harvey Oswald did not act alone and that the killing was in fact the result of a conspiracy. One good reason for that belief, or at least for skepticism as to the truth of the official narrative, is continued government secrecy. To this very day, thousands of government files — mostly produced by the Federal...

As America marked the 50th anniversary of US president John F. Kennedy’s assassination four years ago, a clear majority of Americans (according to polls by Gallup and AP/GfK) still believed that the whole truth of what happened in Dallas on November 22, 1963 remains unknown: That Lee Harvey Oswald did not act alone and that the killing was in fact the result of a conspiracy. One good reason for that belief, or at least for skepticism as to the truth of the official narrative, is continued government secrecy. To this very day, thousands of government files — mostly produced by the Federal...