The term "genocide"--"group killing"--which first appeared in Raphael Lemkin's 1944 book, Axis Rule in Occupied Europe, had by 1948 established itself in international law through the United Nations Convention on the Prevention and Punishment of the Crime of Genocide. Since then the charge of genocide has been both widely applied but also contested. In Genocide: The Act as Idea, Berel Lang examines and illuminates the concept of genocide,...