This book provides a comprehensive account of national parliaments' adaptation to European integration. Advancing an explanation based on political parties' constitutional preferences, the volume investigates the nature and variation of parliamentary rights in European Union affairs across countries and levels of governance. In some member states, parliaments have traditionally been strong and parties hold intergovernmental visions of European integration. In these countries, strong parliamentary rights emerge in the context of parties' efforts to realise their preferred constitutional design for the European polity. Parliamentary rights remain weakly developed where federally-oriented parties prevail, and where parliaments have long been marginal arenas in domestic politics. Moreover, divergent constitutional preferences underlie inter-parliamentary disagreement on national parliaments' collective rights at the European level. Constitutional preferences are key to understanding why a 'Senate' of national parliaments never enjoyed support and why the alternatives subsequently put into place have stayed clear of committing national parliaments to any common policies. This volume calls into question existing explanations that focus on strategic partisan incentives arising from minority and coalition government. It, furthermore rejects the exclusive attribution of parliamentary 'deficits' to the structural constraints created by European integration and, instead, restores a sense of accountability for parliamentary rights to political parties and their ideas for the European Union's constitutional design.

Differentiated integration has become a durable feature of the European Union and is a major alternative for its future development and reform. This book provides a comprehensive conceptual, theoretical, and empirical analysis of differentiation in European integration. It explains differentiation in EU treaties and legislation in general and offers specific accounts of differentiation in the recent enlargements of the EU, the Eurozone crisis, the Brexit negotiations, and the integration of non-member states. Ever Looser Union? introduces differentiated integration as a legal instrument that European governments use regularly to overcome integration deadlock in EU treaty negotiations and legislation. Differentiated integration follows two main logics. Instrumental differentiation adjusts integration to the heterogeneity of economic preferences and capacities, particularly in the context of enlargement. By contrast, constitutional differentiation accommodates concerns about national self-determination. Whereas instrumental differentiation mainly affects poorer (new) member states, constitutional differentiation offers wealthier and nationally oriented member states opt-outs from the integration of core state powers. The book shows that differentiated integration has facilitated the integration of new policies, new members, and even non-members. It has been mainly 'multi-speed' and inclusive. Most differentiations end after a few years and do not discriminate against member states permanently. Yet differentiation is less suitable for reforming established policies, managing disintegration and fostering solidarity, and the path-dependency of core state power integration may lead to permanent divides in the Union.

International parliaments are on the rise. An increasing number of international organizations establishes 'international parliamentary institutions' or IPIs, which bring together members of national parliaments or - in rare cases - elected representatives of member state citizens. Yet, IPIs have generally remained powerless institutions with at best a consultative role in the decision-making process of international organizations. Why do the member states of international organizations create IPIs but do not vest them with relevant institutional powers? This study argues that neither the functional benefits of delegation nor the internalization of democratic norms answer this question convincingly. Rather, IPIs are best understood as an instrument of strategic legitimation. By establishing institutions that mimic national parliaments, governments seek to ensure that audiences at home and in the wider international environment recognize their international organizations as democratically legitimate. At the same time, they seek to avoid being effectively constrained by IPIs in international governance. The Rise of International Parliaments provides a systematic study of the establishment and empowerment of IPIs based on a novel dataset. In a statistical analysis covering the world's most relevant international organizations and a series of case studies from all major world regions, we find two varieties of international parliamentarization. International organizations with general purpose and high authority create and empower IPIs to legitimate their region-building projects domestically. Alternatively, the establishment of IPIs is induced by the international diffusion of democratic norms and prominent templates, above all that of the European Parliament. Transformations in Governance is a major academic book series from Oxford University Press. It is designed to accommodate the impressive growth of research in comparative politics, international relations, public policy, federalism, and environmental and urban studies concerned with the dispersion of authority from central states to supranational institutions, subnational governments, and public-private networks. It brings together work that advances our understanding of the organization, causes, and consequences of multilevel and complex governance. The series is selective, containing annually a small number of books of exceptionally high quality by leading and emerging scholars. The series is edited by Liesbet Hooghe and Gary Marks of the University of North Carolina, Chapel Hill, and Walter Mattli of the University of Oxford.