This article explores the political geography of legal integration in Europe. It asks: how do preexisting state institutions influence processes of political development across space and time? The authors develop a spatiotemporal theory of institutional change, analyzing patterns and paces of domestic judicial enforcement of EU law.

Using an original, geocoded dataset of cases referred to the European Court of Justice by national courts, they visualize subnational penetration of Europe's supranational legal order. The study focuses specifically on France (unitary state), Italy (unitary state), and Germany (federal state).

Key Findings

* National judiciary structure matters: Countries with centralized judiciaries differ from those with decentralized systems in their adoption of EU law.

* Geospatial patterns reveal institutional constraints: Visual analysis shows how domestic political structures shape the spread and implementation of European legal norms.

This research demonstrates that legal integration is spatiotemporally patterned, offering new insights into understanding supranational influence through a geographical lens.