‘Ours is an era of “cases”,’ Diana Trilling wrote several years ago, ‘starting with the Sacco-Vanzetti case in the 1920s, proceeding through the Hiss and Oppenheimer cases to the Rosenberg case, the Chessman case, the Eichmann case, and [the subject of Mrs Trilling's essay]…culminating…in the Profumo case.’ We could add several since then, of course, and her chronology is misleading – the Rosenbergs having followed Hiss but preceded Oppenheimer – but Mrs Trilling's point, that such cases and others provoked within their society basic ‘confrontation(s) between opposing social principles’, remains valid. The Hiss, Rosenberg and Oppenheimer episodes were American society's most controversial post-World War II security cases. Each in turn dramatized the political and cultural impact of the Cold War for large numbers of Americans. They serve as useful paradigms, when examined together, for studying the process by which complex problems of evidence are reduced to compelling images of an event. Almost from the moment the ‘facts’ emerged in each case they congealed, first into partisan accounts and then into minor mythologies, in which each case became the subject-matter for a simple morality tale. Alger Hiss and Whittaker Chambers, Julius and Ethel Rosenberg, Robert Oppenheimer, and the supporting caste in each drama achieved, in their own time, the status of icons in the demonologies and hagiographies of the opposing camps. Looking recently through the dreary record of trials and hearings connected with security problems during the Truman-Eisenhower era, I found certain continuities in the appraisal by intellectuals and politicians of these three otherwise singular episodes.