In research on authoritarianism in Turkey and beyond, there is a growing interest in Ernst Fraenkel’s concept of the dual state from the Nazi era. However, upon closer inspection, these articles lack a systematic application and implementation of Fraenkel’s concept. Mostly, there is no discussion of the strengths and weaknesses of such a ‘diachronic’ conceptual transfer. This case study therefore puts particular emphasis on the methodological issues and on the possibilities and limitations of an ‘updated’ application. As a result, it turns out that Fraenkel’s categories are useful tools to trace how the Turkish administration and judiciary are reorganized along a logic of prerogative power. Fraenkel’s state-centred approach can thus contribute to close a gap left by alternative approaches. However, among the weaknesses even of Dreier and Meierhenrich’s supplement is that the time dimension was, respectively is, not sufficiently taken into account. Dual state structures can be more sustainable than originally assumed by Fraenkel.