Beyond Policy Design: Explaining Stable Divergence in EU Migration Governance

Abstract This article explains the stable and predictable divergence in the implementation of European Union migration and asylum policies across member states. Whilst existing explanations emphasise policy design failures, insufficient solidarity or administrative capacity constraints, they do not account for the persistence of differentiated outcomes over time. The article addresses this gap by introducing the concept of institutional loyalty deficit, defined as a structural condition in which actors formally recognise supranational authority whilst systematically adapting implementation to domestic constraints. The mechanism is specified in four stages, with political salience treated as an accelerating condition and administrative capacity as a determinant of the form divergence takes. Drawing on four analytical illustrations, from Dublin transfers to return policy, the analysis shows that selective implementation constitutes a normalised equilibrium rather than a series of episodic failures. Divergence is an emergent property of shared‐competence governance under uneven enforcement.