Mapping European law
ABSTRACT This article constitutes the first systematic effort to promote a spatial and a subnational turn in the study of EU legal integration by demonstrating how geospatial methods and the selection of a subnational unit of analysis can improve our understanding of the use of the preliminary reference procedure. We conduct a theory testing case study leveraging an original dataset of all references submitted by Italian courts from 1964 through 2013 and utilize geographic information systems (GIS) technology to analyze subnational patterns in reference activity. We use these data to evaluate whether several existing hypotheses explain recent subnational variation in reference rates. We uncover several illuminating findings. First, although population levels and domestic litigiousness best explain variation in reference rates, there is evidence that the domestic litigation effect is subnationally heterogeneous. Second, although use of the reference procedure has diffused since the 1960s, subnational reference rates are spatially clustered by issue area.