Since the late 1990s the question of whether to ratify the status of Swedish as the “principal” language of Sweden by means of a language law has been subject to considerable public dispute. Drawing on Blommaert’s concept of a “language ideological debate,” this paper explores how and why this particular debate seemingly ground to a halt without achieving any kind of tangible closure. In order to do so, we introduce Habermas’s notion of “legitimation crisis” and describe how such crises are, according to Habermas, typically underpinned by one or more “rationality deficits,” i.e. discursive paradoxes that emerge in a given historical, cultural, social and economic context. It is then proposed that the concept of “legitimation crisis” not only may help to explain why some language ideological debates sometimes reach a stalemate at a specific historical moment as in the Swedish case, but also constitutes a theoretical framework that could be productively incorporated into the study of language politics more generally.