I will assume that the question, in the case of France, concerns its North African and subsaharan colonies and protectorates. France was assigned the League of Nations mandate of Syria and Lebanon, but those territories were never considered colonies.

The short answer is that there was nothing in the French colonies that was strictly comparable to the Jim Crow laws in the US, such as legally enforced "white only" water fountains, but the system set in place by colonial authorities was not much better. It is important to understand that, with the notable exception of Algeria, French African and Asian colonies were not settler colonies: the European population was small and highly concentrated in urban areas, with some living in the countryside where they were needed. Algeria was different, with about 10% (1 million in 1954) of settlers living both in urban areas and in the countryside: there, it can be said that the system was, if not Jim Crow-kikz, at least apartheid-like.

Native people living in French colonies conquered in the 19th century were not French citizens, but French subjects. An exception was made for Algerian Jews, who became French citizens in 1870, and for the inhabitants of the "Four Communes" of Senegal in 1916. Throughout the Empire, it was always possible to become a fully naturalized French citizen, but this was reserved to individuals judged exceptional by their merit or their usefulness to the colonial system. Only these (rare) people enjoyed the full rights of regular French people. The rest of the native populations, from the late decades of the 19th century to the end of WW2, were put under a special legal code named Code de l'Indigénat, which set out rules and regulations (and the corresponding punishments) that were only applicable to the native subjects. The Indigénat was first implemented in Algeria in 1875, and variants of it were created for the rest of the colonies (not in Tunisia and Morocco, which were protectorates). There was never a single and unified code: it evolved regularly and all colonies had different versions whose legal value was actually dubious. The main objective of Code was to control the populations. As a French jurist wrote in 1925, the Indigénat was necessary "in countries where Europeans, a minority, are often threatened by fanatical and hostile populations" (cited by Le Cour Grandmaison, 2010). Natives could be fined or emprisoned, more or less arbitrarily, for a vast array of misdemeanours, which varied from a colony to another: showing disrespect to an official, being late in declaring births and deaths, living outside the assigned perimeter of the commune, or travelling without a permit. Sanctions were simply pronounced by military personnel or civilian administrators. In addition to the rules of the Code de l'Indigénat, colonial authorities practiced collective punishments (a whole village could be fined), used coerced labour, could sequester the belongings of people, could have people put in administrative detention, and created special taxes. The political rights of the native populations were much more limited than those French citizens. Access to education and to positions of authority were also limited, and, in the latter case, generally subordinate to people of European descent. Reforming the Code(s) was the subject of heated debates in the first decades of the 20th century, but it took WW2 to finally have it suppressed in French colonial territories.

The central and intractable paradox was that Republican France, who was by definition opposed to American-style, race-based segregation, created policies that were nevertheless based on ethnic categorization and that could be only implemented in the colonies. Native people travelling in France, where they were treated (almost) like regular people, returned with certain feelings about the way they were treated in their homeland (a comparable situation had existed in Ancien Régime France, where slavery was banned on the mainland but normalized in the colonies). The lack of a strong legal framework for the Indigénat, described by some contemporaries - even by those favourable to it - as a "legal monster" (Lecour Grandmaison, 2015), seems to have made the frontier between the colonists and the colonized much less defined than it was in the Southern United States or South Africa. The frontier still existed, but it was could be blurry and moving.

Segregation was mostly organic: Europeans and natives lived in different spaces, culturally and physically. In urban areas, residential segregation took the form of European and native quarters, as it did in all colonial cities. In Algeria, segregation also existed in the countryside, where there were "full-fledged" communes for the colonists, similar to French communes, "native" communes, and "mixed" communes where the two populations coexisted. In Vietnam, the creation of the Central Highlands town of Dalat at the turn of the 20th century is a good example of French-style spatial segregation. Built to provide Europeans with a place where they could escape the tropical climate, Dalat consisted in a French district separated from a native quarter that had grown organically to house the Vietnamese who were working for the Europeans. Zoning Dalat became a priority in the 1920s, and plans were drawn to cordon off the Vietnamese. Those plans were always coded in hygienic terms: officially, the segregation was done for health reasons, not racial ones. The four hotels in Dalat were not officially segregated, but only one was reputed to accommodate Vietnamese guests, and it was located in the Vietnamese quarter. What did happen, however, is that Vietnamese elites, including some who were wealthy, influent, and had full French citizenship, still managed to buy properties in the French quarters, and lived there with the French neighbours. They had the support of some of the French colonists - class trumped race - and of some of the authorities. Nobody was going to deny Emperor Bao Dai the right to have palace/villa there, complete with a swimming pool and other amenities.

In fact, there were always "spaces of socialisation" shared by European and native populations, at each end of the social ladder. In Algeria, the lower-class European colonists, the petits blancs, had often close relations with their native neighbours: they lived among them, went to the same market places, to the same coffee houses, etc. They shared cultural traits, from food to speech patterns. But they drew the line at intermarriage, which remained uncommon due to religious differences though not impossible: there were about 70-80 French-Algerians marriages per year in the 1940s (Alcaraz, 2021). Cultural distance was larger in Asia and Africa, but relationships between French men and native women (the reverse remained rare) were less frowned upon, despite official fears of misgeneation. In West Africa, the tradition of the mariage à la mode du pays, or "marriages in the local fashion", by which a European man took an African woman for his wife (not officially sanctified) for a more or less long-term union, had started in the 17th century as a way for French traders to secure commercial privileges with their African counterparts. The tradition was upheld throughout the colonial period, with merchants, administrators, and military men of all ranks taking local spouses (Jones, 2005; Zimmerman, 2020). Such unions were also relatively common in Indochina. In both continents, they resulted in a lot of mixed-race children, which posed a true conundrum for the authorities (Saada, 2007).

->to be continued