The causes of violations of law beyond the nation state by certain states have been well studied. The sometimes considerable variance between different policy sectors (policy non-compliance) has so far remained largely neglected. Why do the EU Member States violate environmental laws more than twice as likely as EU-driven health and consumer protection regulations? Why account breaches in the field of competition for less than one percent of all breaches, while tax and social policy, in which the EU (Commission) has only limited powers, representing a number more than ten times higher? To explain these sector-specific variances, the project aims bringing together, country-specific, sector-specific and rule-specific explanations of the compliance literature, formulating a set of hypotheses and exploring possible interaction effects between the different variables. The basis for the empirical testing of hypotheses is a database of violations of European law, which was created under a previous DFG-project (BO 1831/1-1) and should be updated and expanded. The database will collect more than 10,000 violations on record against European law over a period of more than 30 years (from 1978 on). The large number of cases, varying from policy sector, member state legislation and the nature and date of the offense, will for the first time allow examining explanations for the occurrence and persistence of sector-specific rule violations in a quantitative study.