On September 21, 1976, Joseph Czarny pointed to a photograph of John Demjanjuk, a Cleveland autoworker and naturalized US citizen, and declared: “This is Ivan Grozny, that is the Ivan, the infamous Ivan. Thirty-three years have gone by, but I recognize him at first sight with full certainty.”When authorities suggested there was evidence Demjanjuk had not been at the extermination camp at Treblinka, Czarny remained adamant that Demjanjuk was the sadistic “Ivan the Terrible.” Ten days later, Gustav Brooks, who had cut the hair of naked women about to be gassed at Treblinka, also identified Demjanjuk as Ivan, “with 100% certainty.”Over the next four decades, John Demjanjuk would be stripped of his US citizenship (twice), sentenced to death in Israel, and convicted in Germany for aiding and abetting the Nazis in murdering more than 28,000 Jews. It would turn out, however, that the longest legal action ever to arise from the Holocaust was a bizarre case of mistaken identity. Demjanjuk was not Ivan the Terrible; he was not a guard at Treblinka.He was, however, a Soviet prisoner of war, who received special training at an SS facility and provided assistance in the extermination of Polish Jews at Sobibor.For this reason, Lawrence Douglas, a professor of law, jurisprudence and social thought at Amherst College and the author of The Memory of Judgment: Making Law and History in the Trials of the Holocaust, has titled his study of the Demjanjuk saga The Right Wrong Man. Sophisticated and suspenseful, the book provides a trenchant analysis of the legal and moral dilemmas surrounding trials for genocidal crimes against humanity.Demjanjuk had every incentive to deny he had been at Sobibor, even if it provided proof he was not Treblinka’s Ivan, Douglas demonstrates, because service at any concentration camp affected the outcome of denaturalization hearings in the United States. And, as Demjanjuk knew, Feodor Federenko, a former guard at Treblinka (then living in Watertown, Connecticut), had been deported to the Soviet Union and executed shortly after he arrived there.The trial in Israel, which began in 1987, Douglas suggests, was complicated by the desire to use survivor testimony to provide “remedial Holocaust education” to a new generation of Israelis. Because judges permitted witnesses to “narrate broadly” (one witness spent considerable time pinpointing where the socks and shirts of guards were hung to dry), they boxed themselves in. They could not cast doubt on the accuracy of their identification of Demjanjuk “without implicitly discrediting the deeper truth” of their accounts of the horrors of camp life.That said, Douglas praises the Supreme Court of Israel for “taking the brave and necessary step” of throwing out the conviction of Demjanjuk as erroneous in 1993.The decision, he reminds us, unleashed a fury in Israel, epitomized by Czarny’s anguished cry “Am I not authentic?” According to Douglas, a coincidence (a German official in the Central Office for the Investigation of Nazi Crimes chanced upon the second deportation order against Demjanjuk) led to the trial of Demjanjuk as an accessory to murder in Sobibor. The German legal system, Douglas reveals, was ill-equipped to add Nazi-era crimes. Rejecting paradigms that called for special courts to adjudicate state-sponsored mass crimes and endorsing “bars against retroactivity” that precluded charging perpetrators with crimes against humanity or genocide, jurists relied on the ordinary criminal code.Nor was it entirely clear (when there was no conclusive evidence of a specific act) what constituted “functional participation” in mass murder. Did one have to kill without orders, in violation of SS law (a standard often set by postwar German courts)? Did it matter that the defendant was acting – or said he was acting – involuntarily? Was it sufficient to establish that a defendant engaged in an activity necessary to the operation of an extermination camp, collecting, sorting and storing the shoes of murdered Jews or working in the bakery? Or did an accessory have to play a demonstrable role in an act of killing? Douglas claims that the Munich trial in Germany broke new ground. It was the first time a German court had tried, let alone convicted, a “foot soldier” of Nazi genocide.And it relied heavily, indeed almost exclusively, on the testimony of professional historians that in death camps culpability followed function as well as individual acts of cruelty or savagery. The historians demonstrated as well that even when prisoners of war like Demjanjuk were pressed into service, their participation in the killing process was not involuntary. They wore uniforms; carried weapons; received pay (and salary increases), regular days off, ready access to tobacco, vodka and women; drew paid leave and free medical care; and were eligible for promotion. Some were allowed to opt out of service, including a guard who asked to be discharged on the grounds that he was “not suited” to this kind of work.Without the efforts of the Wachmänner, who outnumbered the SS by more than five to one at Sobibor, the historians concluded, the Nazis could not have murdered 1.7 million people there.After 93 open sessions over 18 months, the court announced in May 2011 that Demjanjuk was guilty of aiding and abetting mass murder. Sentenced to five years in prison, and asked by the chief judge if he wished to make a statement, the defendant murmured a single word: “Ne.” Demjanjuk died about 10 months later.The Demjanjuk case, Douglas concludes, marked a tacit admission by German courts that they had previously “tortured history by pigeonholing Nazi atrocities into the conventional murder statute.” Although he acknowledges that the admission was belated, coming as it did when the generation of perpetrators had essentially left the scene, Douglas notes that it is in some sense fitting that the era is closing not with a Goering, an Eichmann, or even an Ivan the Terrible in the dock, but a Demjanjuk, whose conviction helps demonstrate that the Holocaust was made possible by the thousands of “replaceable cogs in an exterminatory machine.” Glenn C. Altschuler is the Thomas and Dorothy Litwin Professor of American Studies at Cornell University.