Legislating softly: The effect of preference heterogeneity on the share of EU soft-law instruments over time

This study analyses how preference heterogeneity across EU member states affects the adoption of soft-law acts over time. On the one hand, high diversity in policy preferences is expected to increase the proportion of soft-law instruments because governments are less likely to agree to binding measures. Conversely, preference heterogeneity could also decrease soft law due to the perceived threat of compliance problems. We test these competing arguments using a dataset on all EU soft-law and hard-law instruments adopted between 1967 and 2019. The results show that preference heterogeneity increases the share of soft EU instruments. However, more past heterogeneity prompts EU legislators to decrease the proportion of softer measures in areas that experience high levels of past non-compliance.