In the context of a growing interest in comparative administrative law in Latin America, an emerging academic project asserts the existence of a "common administrative law" in the region, inspired by the so-called ius constitutionale commune in Latin America. In this essay, we examine the impact of the Baena decision (Inter-American Court of Human Rights, 2001) on the administrative regimes of Argentina, Chile, and Mexico so as to reveal the limitations of such a project. We speculate that the limited impact of this decision can be explained by particular characteristics germane to administrative law that tend to be overlooked from a constitutionalist optic. Finally, we draw from our case studies to make methodological recommendations to those who want to undertake comparative administrative law studies in the region.