Resilient Institutions: The Impact of Rule Change on Policy Outputs in European Union Decision-Making Processes

The evolution of the inter‐institutional balance of powers has been a constant feature of the European integration process. Therefore, this thematic issue reopens these theoretical and empirical discussions by looking at an underexploited angle of research, namely the impact of rule change on policy outputs. We offer a discussion on how to theorise rule change, actors’ behaviour, and their impact on policy outputs. We also examine the links between theory and methods, noting the strengths and weaknesses of different methods for the study of institutional and policy change. We draw on the contribu‐ tions of this thematic issue to delineate further paths to push forward the current frontiers in EU decision‐making research.


Introduction
The evolution of the inter-institutional balance of powers has been a constant feature of the European integration process. The debate on 'who wins, who loses' is now at a crossroads: On the one hand, the EU supranational institutions (the Commission, the European Parliament [EP], and the European Court of Justice) have been reinforced in successive constitutional treaties (Dehousse, 2011); on the other hand, the successive crises, which have affected policy areas close to the sovereignty of member states, have reinforced the role of executives and favoured non-legislative forms of decision-making (Puetter, 2014).
Therefore, this thematic issue reopens the theoretical and empirical discussions about inter-institutional power dynamics in EU decision-making by looking at an underexploited angle of research, namely the impact of rule change on policy outputs. While numerous stud-ies have assessed the consequences of rule change for the inter-institutional balance of power (e.g., Farrell & Héritier, 2003;Kreppel, 2018), the question of how rule change affects policy outputs has barely been touched upon. Existing research has focused on a limited pool of policy areas and concentrated on the role of the EP (Bressanelli & Chelotti, 2018;Burns et al., 2013; and the rising powers of the European Council (Bickerton et al., 2015).
This extensive literature points to inconclusive and often contradictory conclusions on the effects that rule change has on the power of EU institutional actors and policy outputs. Therefore, this introduction reflects on how we theorise rule change, actors' behaviour, and their impact on policy outputs. We also discuss the links between theory and methods, noting the strengths and weaknesses of different methods for the study of institutional and policy change. We draw on the contributions of this thematic issue to delineate further paths to push forward the current frontiers in EU decisionmaking research.

Understanding Rule and Policy Change in EU Decision-Making
We consider that rule change cannot have an independent impact on policy outputs; its influence is mediated by the interpretations and use that actors make of these new rules (Figure 1). In addition, we are interested in understanding both positive and negative instances of policy change.
We consider three main sources of rule change. First, formal changes equate to treaty reforms and inter-institutional agreements. The introduction of codecision in the Treaty of Maastricht and its subsequent modification and expansion in Amsterdam and Lisbon is a central instance of formal rule change. However, 'interstitial' processes emerging from informal practices in-between treaty changes (Farrell & Héritier, 2007) have often had more pervasive effects than formal changes. A good example is the increase in early agreements and the use of trilogues in co-decision (Brandsma et al., 2021). Informal changes have also been the product of crises that have empowered executive organs such as the European Council, the Commission, the European Central Bank, and EU agencies.
Rule change may have different types of effects: First, it might introduce new actors into the field, as we have seen with the gradual empowerment of the EP as a co-legislator. Second, it might modify formal competences: The last treaty reforms saw a crucial shift from regulatory competences to EU involvement in core state powers, such as economic and monetary policies as well as justice and home affairs (Genschel & Jachtenfuchs, 2016). Finally, rule change can also act as a window of opportunity, notably when coupled with crises and uncertainty.
On the other hand, the study of policy change is often unsystematic, making it difficult to compare findings. We invite researchers to ask themselves: First, what is the status quo? Is it previous EU legislation? What was the status quo before any EU legislation was in place? What is the actual implementation on the ground once EU legislation has been adopted? Second, to what extent has the content of the policies changed (quantity)? Third, how deep does this change go (quality)?
Finally, we need to assess whether these (non-)changes can actually be attributed to the (strategic) use of rule change by specific actors since not all policy changes will have their source in the rule change. Indeed, rule change is a necessary but not sufficient condition for policy change; therefore, in order to explain outcomes, we need to pay particular attention to the mechanisms of policy change. Policy entrepreneurs might mobilise different types of mechanisms based on actor-centred strategies (e.g., purposefully including or excluding certain actors), ideas (framing solutions, linking issues), and processes (shifting venues, using norms to legitimise certain decisions).

Studying Rule and Policy Change in EU Decision-Making
Explaining the linkage between rule and policy change requires a broad methodological toolbox. In the past, the effects of changes in formal and informal rules have been dominated by formal modelling and quantitative methods which have provided general explanations about decision-making but often failed to account for the mechanisms leading to policy change. On the other hand, qualitative studies have remained compartmentalised and often failed to describe the general picture across policy fields.
The study of rule and policy change in EU decisionmaking has been dominated by game-theoretical and spatial models. These models consider that, taken together, actors' preferences, the location of the status quo, and the EU procedures determine policies (Crombez & Vangerven, 2014, p. 290). Formal models contributed greatly to the understanding of the different EU legislative procedures, the power of the EU institutions, and the degree of gridlock. However, they often failed to take the increased informalisation of EU legislative procedures into account and have tended to treat EU institutions as homogenous actors (Thomson et al., 2006). Some of these caveats have been addressed by bargaining models which use expert interviews, voting behaviour, or EP election manifestos to locate actors' positions on specific policy issues (e.g., Hix et al., 2007;Thomson et al., 2006). However, one of the main difficulties in using quantitative methods to study rule and policy change comes from the availability and quality of data. Indeed, formal powers, partisan ideologies, and parliamentary amendments provide only an approximation of influence and policy positions, as they do not capture, for example, informal negotiations, and they often measure only the revealed/strategic preferences of actors.
These details can be captured with qualitative methods which focus on the role of actors and the understanding of their functions and power. A sizeable body of work has analysed the impact of rule and institutional change on the substance of European policies, such as agriculture (Greer, 2005), macroeconomic policies (Hodson, 2011), environment (Burns & Carter, 2010), justice and home affairs (Tacea, 2018;Trauner & Ripoll Servent, 2015), and social policies (Falkner et al., 2005). These studies offer in-depth analyses of the conditions and mechanisms in different policy areas. However, most of them are case studies examining very salient EU proposals and focusing on new areas of EU activity, which limits their generalisability beyond their policy field.

Contributions of This Thematic Issue
The contributions of this thematic issue offer significant insights on the effects of rules change on policy change by combining quantitative and qualitative perspectives. Most contributions depart from Lisbon as the most significant turning point for the EU's architecture in the last decades. The expansion of co-decision and consent have made a significant difference, both in formal and informal terms (Gravey & Buzogány, 2021;Laloux & Panning, 2021;Peffenköver & Adriaensen, 2021;Piquet, 2021;Tacea, 2021). Zeilinger (2021) underlines how, despite its limited role in labour market and social policies, the Commission acts as a policy entrepreneur in these areas through Country-Specific-Recommendations. However, we also see that crises have served as crucial windows of opportunity, especially for the Commission, which has often used them to redefine its powers in areas where it did not have strong competences (Vaagland, 2021;Zeilinger, 2021).
When it comes to the mechanisms of change, we see how rule changes have indeed led to new forms of competition that force us to assess winners and losers beyond the traditional institutional triangle. Several contributions show that the Commission is now more dependent on the EP, which has led to new forms of early consultation and cooperation in formal procedures (Gravey & Buzogány, 2021;Peffenköver & Adriaensen, 2021). However, this dependency has also pushed the Commission to strategically increase the use of nonlegislative procedures in order to circumvent the legislative powers of the EP (Tacea, 2021;Vaagland, 2021). Indeed, in a context of higher politicisation and conflict, Commission actors have been particularly effective in re-framing proposals or linking them to other issues to expand their chances of success (or block alternative understandings). Laloux and Panning (2021) show the importance of anticipating conflicts to explain the success of individual Commissioners, which often involves re-framing and issue-linkage to mobilise epistemic communities around an idea (Vaagland, 2021;Zeilinger, 2021). Finally, we see how politicisation has become crucial to explain the role of actors in proactively using the decision-making process to bias or block policy change. This is particularly visible in a highly frag-mented European Parliament, which makes it easier for particularistic interests and those happy with the status quo to win (Gravey & Buzogány, 2021;Vinciguerra, 2021). Piquet (2021) and Peffenköver and Adriaensen (2021) also show the crucial role that inter-actor communication plays in understanding how gridlock and unwanted policy change can be prevented.
By using quantitative, qualitative, and text-mining techniques, this thematic issue bridges the gap between empirical case studies and large-N analyses. Indeed, various contributions show the advantages of using process-tracing and structured (theory-led) comparisons to uncover the mechanisms linking rule and policy change (Peffenköver & Adriaensen, 2021;Vaagland, 2021;Vinciguerra, 2021;Zeilinger, 2021). Piquet (2021), Gravey and Buzogány (2021), and Vinciguerra (2021) demonstrate the importance of mixed methods to explore mechanisms and explain patterns of rule and policy change. Finally, Laloux and Panning (2021) and Tacea (2021) use text mining to capture how much change an actor introduces during the legislative process and explain their success/failure. Therefore, the thematic issue demonstrates the need to strengthen the dialogue between institutionalists and policy analysts but also between formal modellers, quantitative, and qualitative researchers in order to gain a better understanding of the patterns and mechanisms of change and stability in EU decision-making.