Review of the Evidence
The empirical chapters of this study investigated variation in the creation of EU-related parliamentary oversight institutions in response to the deepening of European integration owing to the major treaty reforms since the mid- 1980s (Chapters 4 and 5); parliamentarians' individual-level preferences regarding different proposals to give parliaments a direct European role (Chapter 6); and, finally, in the context of the reforms that the EU has recently implemented in the area of economic and monetary union, national parliaments' adaptation to European Stability Mechanism (ESM) decision-making and their preferences as to the design of the new inter-parliamentary Article- 13 conference (Chapter 7).
The analysis of EU-related oversight institutions revealed a substantial effect of parliamentary parties' constitutional preferences on the strength of oversight institutions that they have at any given point in time and on the likelihood that they decide on reforms in reaction to steps to deepen European integration. The strength of existing parliamentary rights and competences in national policy-making, as measured through the rights of parliamentary committees, furthermore, have a positive impact on how significant the changes are that parties implement in response to EU treaty revisions. These findings support the theoretical argument. They are also in line with existing contributions in the literature that stressed the relationship between party support for the EP (Winzen etal. 2015), which could be taken as an indicator of parties' constitutional preferences, as well as with studies that find an effect of existing institutions (Dimitrakopoulos 2001; Raunio 2005; Benz 2004; Karlas 2012). Unlike several of these studies, however, the argument here stresses that institutions matter for a particular reason, namely because they reflect past constitutional conflicts and constitutional preferences that have since become accepted domestically and constrain the reforms policy-makers consider appropriate in EU affairs. Institutional effects are, thus, part of a more general explanation of parliamentary adaptation based on constitutional preferences. In supporting such an explanation, the findings, taken together, are different from studies arguing that institutions reflect contemporaneous incentives for influence-seeking parliamentarians (Benz 2004). And although Dimitrakopoulos (2001) is, thus, right in relating the effect of institutions to domestic policy-makers' conceptions of appropriate institutional change, his argument, being limited to what constrains parliamentary adaptation to integration, nonetheless, stops short of fully identifying the impact of constitutional preferences. It is not only the case that the existence of weak parliamentary rights limits parliamentary adaptation, as Dimitrakopoulos illustrates. Adaptation is also strong where parliaments have far-reaching domestic competences. Moreover, these institutional effects are part of a broad explanation that also takes into account the impact on EU-related oversight institutions of parties' federal and intergovernmental views of the right constitutional design of the EU.
In contrast to an explanation based on constitutional preferences, arguments putting emphasis on the partisan exigencies arising from minority and coalition government turn out to be of limited empirical relevance. The evidence thus speaks out against the idea that strong EU-related oversight institutions exist or emerge only or primarily in times of minority government (Martin 2000; Bergman 2000). It appears that the coincidence of strong EU competences and regular minority rule in Denmark has had an undue impact on scholars' intuitions on why parties and parliamentarians seek to create parliamentary rights in EU policy-making. In contrast to expectations that coalition conflicts would lead to legislative institution-building in EU affairs (Saalfeld 2005), no relevant effect exists empirically regarding conflict between coalition partners on the left-right dimension of political contestation. Having said this, there are signs that, in the very rare cases of European cabinets being seriously divided in their support for European integration, reforms of EU-related oversight institutions follow. It should be stressed, however, that these situations are so rare that they should not be seen as the most relevant explanation of parliamentary adaptation to integration. What is more, for reasons discussed in detail in Chapter 3, support for European integration should be seen as an indicator of parties' constitutional preferences. Finding that coalition conflict over parties' constitutional preferences enhances institutional reform is, therefore, while not fully in line with the reform processes envisaged here, not incompatible either.
Investigating parliamentarians' individual-level preferences for different proposals to give national parliaments a direct role in EU affairs, Chapter 6 found a strong constraining effect of existing EU-related and domestic parliamentary rights and capacities. Constitutional preferences mattered, albeit only when federalists and intergovernmentalists did not agree, as for instance regarding the suggestions to integrate members of the EP into national parliamentary proceedings—a reform intergovernmentalists oppose. In contrast to the existing literature that focuses on negotiations between parliaments over how to design their direct role in EU affairs (e.g. Rittberger 2005; Kreilinger 2013; Herranz-Surralles 2014; Cooper 2014), the analysis presented here sheds light on the factors underlying parliamentary preferences. Thus, it does not dispute the insights of already available contributions that show, most importantly, how disagreement between different member state parliaments pushes outcomes towards the lowest common denominator—that is, towards outcomes that leave the freedom to decide over their own extent of participation in EU policy-making to each national parliament. The added value rather is to show the origins of inter-parliamentary disagreement and, in drawing on the assumptions and arguments used to explain the creation of EU-related oversight institutions, to establish a connection between analyses of different facets of national parliaments' adaptation to integration.
Finally, the analysis of the parliamentary reforms national parties decided on in response to the recent reforms of the EU's Economic and Monetary Union showed a particularly strong impact of existing institutions. In countries in which parliaments have strong institutional rights in the domestic budgetary process, they acquire strong rights in ESM decision-making. Moreover, where far-reaching EU-related oversight institutions exist, parliaments advocate a narrowly circumscribed mandate for the new inter-parliamentary Article-13 conference envisaged in the Treaty on Stability, Coordination and Governance (TSCG). While these results are in line with the arguments and evidence of the previous chapters, they suggest no effect of the federal or intergovernmental inclinations of parliamentary parties. This was to be expected in light of strongly intergovernmental character of the ESM treaty and the findings of Chapters 5 and 6. A strong Article-13 conference will be regarded with scepticism by federalists, who see it as a threat to the European- level pre-eminence of the EP, as well as by intergovernmentalists, who see it as a distraction from the domestic orientation of parliaments in EU affairs. In the case of parliamentary adaptation to ESM decision-making, parties' intergovernmentalism or federalism should not matter because of the strongly intergovernmental character of the ESM. This strongly intergovernmental character appeases intergovernmentalists and reduces their demand for the creation of significant national parliamentary competences. The lack of co-decision rights for the EP, in turn, motivates federally oriented parties to seek domestic parliamentary adaptation. The analysis of parliamentary adaptation to the new institutions of economic and monetary union, finally, revealed effects of political-economic factors. Highly indebted countries and contributors to the EU budget appear to be particularly interested in interparliamentary cooperation to monitor European level economic and fiscal policy-making. These or other issue-specific factors might also matter for parliamentary reforms more generally in addition to the general factors put forward here.