Colonial Algeria was in a peculiar situation in regards to the French legal tradition, since citizenship and nationality were legally distinguished: the natives, the Indigènes, were recognised as French but were rejected as citizens. The purpose of this article is to trace the categorization of citizenship in Algerian colonial law. It becomes clear then that, through this attempt to construct a legal coherence, the exceptional character of colonial domination was continuously denied. In conclusion, this legal formalization appears to be incomplete and imperfect; instead of being a fact, it seems to have constrained – and sometimes even to have offered argumentative possibilities to – colonial actors.