In 1948, the UN General Assembly adopted the Convention on the Prevention and Punishment of the Crime of Genocide (CPPCG), legally defining the crime of genocide for the first time. Amazingly, the United States did not ratify this international agreement until nearly 40 years later, when President Reagan finally signed the genocide convention bill. Attempts to enforce international law against genocide did not begin until the 1990s.

"Genocide: A Reference Handbook" examines the antecedents of the term "genocide" in the mid-19th century and explains the current challenges of preventing...