Compliance studies thus far have largely focused on a binary assessment of state behaviour to understand why states comply or fail to comply with international law. This article expands on this literature by further delineating the concept of over-compliance. If compliance is costly, why do states choose not merely to meet, but to exceed, international minimum requirements? This article presents a theoretical framework through which to explain over-compliance, examining the explanatory power of rationalist and constructivist explanations as to how membership in an IO can cause states to adopt over-compliant behavior. It suggests over-compliance results from specific incentive structures during accession processes to international institutions. To further their chances to obtain admission, states whose compliance with membership rules has been questioned, signal their commitment to international cooperation through the adoption of over-compliant legislation. A comparative case study of the Baltic states’ parental leave regime finds empirical support for this argument.
