Since Raphael Lemkin's pioneer work, several scholars have published comparative studies on genocides. The works of Leo Kuper, Helen Fein, Frank Chalk and Kurt Jonassohn are among the best known. However, they have not been able to agree on a definition of the concept of genocide. Researchers go from a sweeping approach – such as the one favored by the Encyclopedia of Genocide – to a more restricted one, based on the United Nations 1948 Convention on the Prevention and Punishment of the Crime of Genocide, favored by Ben Kiernan, the founder of the Genocide Studies Program at Yale University.

Considering that the UN definition is both too narrow and too restrictive, other scholars have introduced new terminology, such as “politicide” or “democide.” The 1990s saw a growing number of comparative studies on “massacres” that distanced themselves from former studies on genocides: among them, the works of Brenda Uekert, Denis Crouzet, Mark Levene, Stahtis Kalivas, Luis Martinez, and myself. In some of them, the dividing line between “genocide” and “massacre” disappeared, leading such authors as Brenda Uekert or Yves Ternon to use the expression “genocidal massacres.” In addition, Mark Levene gave a definition of “massacre” that is close to the definition of “genocide” given by other scholars, that is, “one-sided killings.”

And yet, it is essential that the words “massacre” and “genocide” be clearly and precisely differentiated, if only for one reason, that “genocide” comes under international law.