Why did Bismarck's annexation of Alsace-Lorraine conflict with the principle of self-determination?

Bismarck’s annexation of Alsace-Lorraine in 1871 conflicted with the principle of self-determination because it transferred territory and its inhabitants between sovereign powers without regard for the political will or national identity of the local population.12

While the annexation was justified by the German Empire based on the region's historical associations and its large German-speaking population, the move disregarded the inhabitants' own aspirations. Following the transfer, the population remained largely loyal to the French Republic, and many residents actively protested the annexation, with thousands choosing to emigrate rather than live under German rule.1

By incorporating the region as a Reichsland (imperial state) and denying it effective self-government for decades, the German administration suppressed the local population's right to choose their own political status. This imposition of sovereignty over a people who identified with another nation directly violated the ethical principle that populations should have the freedom to determine their own political, social, and cultural systems.12