In recounting the interventions of Belgian lawyers in the institutionalization of the discipline of international law at the end of the 19th century and the beginning of the 20th century, Vincent Genin’s Le laboratoire belge du droit international offers new materials and documentary evidence of the complicity between the construction of the international legal discipline and the colonial project. Taking his cue from Martti Koskenniemi’s Gentle Civilizer, Genin has produced a biographical and agent-based historicization of an unprecedented archival rigour, allowing international lawyers, and especially Belgian international lawyers, to take another hard look at the dark roots of their tradition.