The Role of Political Actors’ Preference Variation in the Decision-Making Process of the European Union

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

The revised manuscript may be considered to cover the bare minimum standards to warrant publication. I am still concerned about the definition of interest groups and member states as "critical stakeholders." Such an equal-order treatment of interest groups and (and their conflicts) and the heterogeneity of member states' preferences obscures the process of preference formation for the EU member states anchored in domestic politics (exporters, interest groups, consumers...). Process tracing is otherwise conducted in a systematic way allowing for a conclusive discussion of the evidence.

Please proofread the text.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I would like to thank the author for the revised version of the manuscript, as it is clar that s.he has put a lot of effort to revising it, and for the clear answer to my comments. However, I am sorry but must maintain my decision to reject the paper. In my view, the fundamental issues remain too substantial, and the revisions made in response to my comments are insufficient to address them.

 I believe that most of my comments on the previous version of the paper remain valid. In particular, I find that the paper is still quite unclear in several places, making it often difficult to see the author’s point and what s•he is trying to convey. In addition, I have three additional points regarding the revisions:

1.     While the author has improved the literature review, it is still not comprehensive enough. It gives the impression that the author has cherry-picked some studies rather than providing a balanced and thorough overview of the relevant literature.

2.     I believe the observable implications should also concern more directly the relationships between the components of the mechanism rather than merely the presence of those components.

3.     The justification for the case selection remains unconvincing. First, the author claims that the EU legislative procedure has not fundamentally changed since 2003, but this is highly debatable. Since then, significant developments have occurred, including the 2004 enlargement, the Lisbon Treaty, and the increasing institutionalization of trilogue negotiations. Second, the author is not clear enough on the TTIP . On one hand, the author sometimes refers to it as a legislative process -which is hardly the case. On the other hand, it is unclear which procedure is being discussed: the actual negotiations with the USA (which was conducted by the Commission and not the member states…)  or the Council's recommendations—neither of which qualify as non-binding legislation. The author references 2014/2228(INI), but this is a recommendation from the European Parliament, in which the Council and, therefore, Member States were not involved. This raises questions about how the mechanism can be applied in this particular case.

I regret having to maintain my decision to reject the manuscript, but I believe that the paper requires a thorough overhaul rather than marginal revisions -notably on its aim and what it can (and cannot) do with the empirical analysis. It is only with such a substantial reboot that it has the potential to make a clear and meaningful contribution to the literature

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

This is not the simplest of articles, to be sure. However, it rewards its readers with a range of insights, in terms of identifying political actors, defining and explaining their preferences both AS actors, and in terms of preference variation, set against the overall multilevel decision-making processes of the EU. The article explores the complex role of multi-level actors (in this case EU member states and interest groups), and their ability to play key roles as political actors, and more specifically to play central, frequently causal roles in within the wider terrain of EU decision-making by virtue of the variation  / heterogeneity of their given preferences, both endogenous and exogenous.  This is an area that is well covered in many areas of literature and research, but from so many different directions that a clarified piece of work that - based on process-tracing - looks at the stakeholders involved in a generally clear way, but with the added benefit of a contemporary set of two case studies—the Transatlantic Trade and Investment Partnership (TTIP) and the EU Emissions Trading System (EU ETS)— which are used n this article to investigate the specific causal mechanisms that link actors' preference heterogeneity to and within the duration of decision-making processes. 

The paper provides an in-depth analysis of how preference heterogeneity among political actors, specifically interest groups and member states, influences the decision-making process within the European Union (EU). The study employs process-tracing to examine two key cases: the EU Emissions Trading System (EU ETS) and the Transatlantic Trade and Investment Partnership (TTIP). 

In terms of policy domain and objectives, the primary distinction between the two cases lies in their policy focus. The EU ETS is an environmental policy initiative designed to regulate greenhouse gas emissions through a market-based mechanism. Its main objective is to reduce carbon emissions by capping total emissions while allowing companies to trade allowances, thus incentivizing emission reductions. In contrast, TTIP was a trade and investment agreement aimed at reducing regulatory barriers and enhancing economic integration between the EU and the United States. The focus was on eliminating tariffs, harmonizing regulations, and facilitating transatlantic investment.

The article is less clear on HOW these two cases studies are different, and how this in turn could affect the salience of actor choices. As a reminder, EU ETS stakeholders were primarily technical experts and environmental policy advocates within the EU’s governance structure, whereas TTIP faced intense public scrutiny and political activism, with significant opposition from civil society groups and national parliaments.

The article has interesting insights in a number of areas, including the linear connection between input, throughout, and output, in terms of decison-making process, a broadly well thought out causal mechanism in terms of determining the goal, and indeed the length of the decision-making process. 

The article is clearer on the complexity of negotiations also varied between the two cases. The EU ETS evolved through a series of legislative amendments and regulatory adjustments within the EU’s existing institutional framework. Though negotiations were often prolonged due to disagreements over emission allowances and carbon leakage protection, the process remained within the EU’s policymaking structures.

In contrast, TTIP negotiations were far more complex due to the involvement of two sovereign entities—the EU and the U.S.—each with different regulatory philosophies and economic interests. Unlike EU ETS, which operated within an established legislative framework, TTIP negotiations had to reconcile fundamental differences in trade regulations, environmental and labor standards, and dispute resolution mechanisms. Further work could have been undertaken on the role of the 'intermediate mechanisms', in terms of overall transaction costs - this was not particularly clearer explained, either generically or in terms of the ETS/TTIP case studies. I am not a great expert in the field, but I would argue that the article does break new ground in enlist the differences between four hypothesis tests developed from Bayesian Logic.

The comparison between EU ETS and TTIP underscores how preference heterogeneity impacts decision-making in different policy contexts. While both cases involved significant stakeholder engagement and complex negotiations, the nature of their challenges differed. EU ETS faced technical and economic hurdles within an existing regulatory framework, whereas TTIP encountered ideological and political obstacles that led to its failure. The study effectively highlights how issue salience, public opposition, and the institutional setting shape the trajectory of EU policymaking.

The paper could benefit from further exploration of alternative explanations for decision-making delays in both cases. Additionally, examining the role of domestic political dynamics within key member states could provide deeper insights into how national interests shape EU policymaking. Finally, a comparative analysis with other failed trade agreements or successful climate policies could strengthen the study’s generalizability.

Overall, this research provides a generally helpful analysis of how preference heterogeneity influences the EU decision-making process, offering valuable insights for scholars and policymakers alike.

The findings reveal that preference heterogeneity arising from actor decision-making functions itself as a multidimensional factor, rolling in both outright disagreements, but - more crucially - the unrestricted interplay of diverse interest group demands, set against the the targeted, frequently strategic positioning of 16 member states within institutional frameworks. In sum, the article is generally clear in its ability to identify specific mechanisms, which in turn helps to reveal the need in scholarship to pay greater attention in the need to account for varying levels of 'issue salience' and their ongoing impact on procedural dynamics  within legislative strategies. 

I would in conclusion agree with the findings postulated, i.e. that the range of causal mechanisms that were causally operable relative to TTIP and ETS. The alignment set up is that negative opinions of interest groups operate parallel to the heterogeneous preferences of the MS attached to  these two cases. Meanwhile, the the end result of the specific input of cited interest groups within these cases generally coincides with 'throughput' agreement/ legitimacy of the MS own positions (e.g. in Council), ensuring is determinative causal relationship between the preference-based heterogeneity of political actors and the length of the decision-making of the EU.

Comments on the Quality of English Language

As above.

Author Response

Comment 1: [The article is less clear on HOW these two case studies are different, and how this in turn could affect the salience of actor choices.]

Response 1：

I have revised the manuscript to provide a clearer comparison between the EU Emissions Trading System (EU ETS) and the Transatlantic Trade and Investment Partnership (TTIP). The differences in the policy focus of both cases are now more explicitly explained, highlighting that the EU ETS primarily involved technical experts and environmental advocates within an existing regulatory framework, whereas TTIP faced greater public scrutiny and political activism, which influenced the decision-making process differently. This revision should clarify how the salience of actor choices varied across these two contexts.

More specifically, in the “case selection and sampling”(section 4.2), a comparative table has been added to systematically contrast the two cases across four dimensions: policy type, stakeholder structure, public engagement level, and institutional constraints (see revised manuscript page 9-10, lines 405–406).

In the “discussion (section 6)”, supplementary analysis has been incorporated to clarify that the technical nature of EU ETS concentrated interest bargaining within expert communities and industry lobbies, whereas the highly politicized nature of TTIP subjected it to challenges from civil society movements and domestic parliamentary veto points. I also explained how the divergence in issue salience shapes member states’ preference aggregation patterns through media visibility and public risk perception (see page 20, lines 895–906).

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Comment 2: [Further work could have been undertaken on the role of the ‘intermediate mechanisms’, in terms of overall transaction costs–this was not particularly clearer explained.]

Response 2: Thanks for this valuable suggestion. I will expand the intermediate mechanisms (section 3.3) and add explanation of operationalizing Mediating Mechanisms, explicitly defining “number of institutional veto points” and “coordination costs of preference aggregation” as core mediating variables in the next paper. In the revised manuscript, I particularly focus on how transaction costs played a role in the EU ETS and TTIP cases (section 5.1). So, I embedded mechanism-specific analysis into the case studies: (1) For TTIP, I demonstrated how disagreements on EU-U.S. food safety standards in the regulatory cooperation chapter triggered a “proliferation of institutional veto points” (page 16, lines 701-706). For EU ETS, I analyzed how heterogeneity in member states’ industrial structures escalated coordination costs during negotiations over carbon leakage compensation (page 18, lines 825-833). This section now provides a more detailed discussion of the transactional aspects involved in both cases and how they influenced the decision-making processes. I hope this provides additional clarity to the readers.

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Comment 3: [The paper could benefit from further exploration of alternative explanations for decision-making delays in both cases. AND a comparative analysis with other failed trade agreements or successful climate policies could strengthen the study’s generalizability.]

Response 3: I have added sentences in the discussion (section 6) discussing alternative explanations for decision-making delays, incorporating the idea that external factors, such as changes in global economic conditions or shifts in the political environment, bureaucratic procedures, and strengthen case comparisons could also have contributed to delays. Besides, I have added a comparative perspective that explores other failed trade agreements and successful climate policies to strengthen the generalizability of the findings. This section compares TTIP with the Comprehensive Economic and Trade Agreement (CETA) between the EU and Canada (page 21, lines 982-991). The analysis highlights how divergent intensities of public backlash (e.g., anti-TTIP activism vs. CETA’s localized resistance) shaped contrasting negotiation outcomes. Also add the limitations in the conclusion (section 7) discussing the potential impact of external shocks in diverting resources from TTIP negotiations (pages 21-22, lines 992-1008). This argument is contextualized by citing a 2015 European Commission internal document, which demonstrates the crisis’s limited substantive effect on negotiation priorities. This should provide a more comprehensive view of the factors influencing the pace of decision-making in both cases.

 

Comment 4: [Examining the role of domestic political dynamics within key member states could provide deeper insights into how national interests shape EU policymaking.]

Response 4: I agree with the reviewer’s suggestion and have incorporated a discussion on the role of domestic political dynamics, particularly within key member states. This section explores how national interests, such as economic considerations and political pressure from domestic interest groups, shaped EU decision-making in the cases of EU ETS and TTIP. I also added a case study on domestic parliamentary debates in Germany and France within the TTIP analysis, supported by a new table (Table 6) illustrating shifts in public approval rates in both countries (page 15, lines 654-666). This demonstrates how domestic electoral cycles shape member states’ negotiating positions in the EU Council through the “political commitment constraint” mechanism (e.g., pre-electoral rhetoric hardening national stances). Supplemented the analysis with recent interview data (from an EU Directorate-General for Trade official, 2023), clarifying how industry lobbying groups in member states leverage domestic legislative channels (e.g., parliamentary resolutions, coalition agreements) to indirectly pressure EU agendas.

Here is the additional explanation below:

Domestic political dynamics within key EU member states play a crucial role in shaping EU policymaking, as national interests often influence how governments engage with EU decisions and negotiations. Each member state has its own domestic political environment, economic priorities, and public opinion, which can affect its stance on EU policies. These dynamics can shape the overall EU decision-making process in several ways:

(1) Political leadership and party alignment. The priorities of the national government, influenced by the ruling political parties, often align with the government’s domestic agenda. A shift in leadership, such as a change in the party in power, can drastically alter a country's position within the EU. For example, populist or nationalist governments may push for policies that prioritize national sovereignty and reduce EU integration, while more pro-EU governments may advocate for deeper cooperation and EU-wide solutions.

(2) Domestic pressure groups and public opinion. Public opinion and domestic interest groups (e.g., labor unions, industry lobbies, environmental organizations) can exert pressure on national governments, influencing their negotiation strategies and positions within the EU. Governments must balance national interests with their EU commitments, often taking into account domestic protests or demands. For instance, public opposition to free trade agreements like TTIP may force governments to adopt more cautious positions, even if they initially supported such agreements.

(3) National economies and sectors. Member states with specific economic interests, such as agriculture, industry, or finance, often try to influence EU policies to protect or advance their economic sectors. For example, countries like France or Spain, with strong agricultural sectors, might push for more protectionist agricultural policies within the EU, while Germany may advocate for policies that benefit its industrial base.

(4) Intergovernmental bargaining and veto points. Within the EU’s complex governance structure, national governments engage in intergovernmental bargaining, often using their veto power to block or influence decisions that do not align with their national interests. For instance, key member states can block or delay EU-wide agreements if they believe such agreements would disadvantage their national priorities.

(5) domestic political polarization. When national politics are highly polarized, governments may take more extreme positions within the EU to satisfy their domestic political base. For example, if anti-EU sentiments are rising within a member state, its government may adopt more confrontational positions in negotiations to appease nationalist or Eurosceptic voters. This can lead to slower decision-making and even gridlock at the EU level, especially when multiple member states adopt similarly polarized positions.

In summary, domestic political dynamics within key EU member states are critical in shaping EU policymaking. National governments should navigate the complex relationship between their domestic constituencies and EU obligations, balancing domestic political pressures with broader EU interests. This interaction is a major factor behind delays, compromises, and the success or failure of EU policies and agreements.

I appreciate the reviewer’s positive comments on the clarity of the analysis. I have taken extra care to emphasize the varying levels of issue salience and how they affect procedural dynamics. I have also ensured that the discussion of the causal mechanisms linking preference heterogeneity to decision-making is more thoroughly explained, in line with the reviewer’s recommendations.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper examines whether the interaction between the preference heterogeneity of stakeholders and member states has a causal effect on the duration of the EU legislative process. To achieve this, the authors apply process tracing to analyze two legislative cases (although one of the cases is a resolution rather than a piece of legislation). Using a comprehensive array of data, their analysis supports the existence of a causal mechanism.

While the paper certainly has some merits, notably the impressive data collection, it currently has too many flaws to be considered for publication. The research question is not clearly defined and may be trivial. Additionally, there is no proper literature review, despite the existence of decent literature on the topic. The hypothesized mechanism and methodology are unclear, and the analysis is too shallow to support the authors’ claims

First of all, the research's exact question or objective is unclear to me. The paper states that the interaction between the heterogeneity of Member States and stakeholder preferences leads to longer decision-making. On the one hand, this seems somewhat trivial, as it is fairly obvious that disagreement will lead to a lengthier decision-making process compared to a scenario where everyone agrees. On the other hand, it is unclear what the authors mean by “interaction”—do they mean that the heterogeneity of preferences among Member States and stakeholders occurs independently and when both occur it has a particular effect, and if so, what is exactly the cause that triggers the mechanism leading to the lengthy decision-making process?

However, in the rest of the paper, the authors seem to suggest that there is a causal link between the two factors (eg. line 210: "Moreover, stakeholders’ demands affect member states preferences and their strategies in the EU decision-making process"), which implies the relationship between both is different. As I understand it, the point should be instead to investigate whether disagreements among stakeholders affect the length of the EU legislative procedure by creating conflicts between Member States and increasing the transaction costs of reaching a decision. This is an appropriate mechanism to explore. I think the authors should reformulate the introduction along these lines, taking stakeholder heterogeneity as the cause and examining the mechanism whereby this heterogeneity affects decision-making through its effect on member states' preferences and thereby disagreements.

Furthermore, nowhere in the document does the author define what is meant by ‘stakeholder,’ nor do they distinguish between different types of stakeholders. This is a significant oversight, as the literature shows that different types of stakeholders (e.g., business vs civil society interest groups) can have varying impacts on the EU legislative process

Second, the paper does not discuss the existing literature on the duration of the EU decision-making process or position itself within this body of work. This lack of engagement with the relevant literature weakens the paper’s contribution and makes it difficult to understand how the research contributes to or differs from previous studies.

Third, the paper lacks a proper mechanism linking the cause(s) (which is?) to the outcome through causal steps, as described notably by Beach and Petersen. This is crucial in process tracing. The current approach makes the process tracing shallow at best, as the causal mechanism triggered by the two (three?) causes is not clear. The paper does not break down the mechanism into entities and activities, nor does it discuss the contextual conditions or the different configurations of conflicts that may take place. For instance, arguably the two cases studied are rather salient ones, how does that matter for the "mechanism" at stake? 

Fourth the observable manifestations defined by the author are vague and not always clearly linked to the cause, and therefore not rigorous enough to test the mechanism. For example, what are the exact manifestations of the fact that ‘policy outcomes are shaped by the configuration of Member States and the demand of interest groups’, this is true for many different outcomes and, in one way or another, for all legislative files... The same is true for ‘Heterogeneous stakeholder views can shape decision-making outcomes by influencing negotiations between Member States in the Council’. The statement is too broad. Clearly, they ‘can’, and the thing is that they ‘could have’ even in some cases where this is not the case. Even if the link were clearer, these points would require observable manifestations. Finally, the last observable manifestation is actually that the expected relationship takes place, which is the whole point of the article. This is a process in itself, not an empirical manifestation of a process.

Additionally, there is no presentation of the third cause, which is only named and is actually discussed simultaneously with the outcome of the mechanism. Moreover, the observable manifestations of both are the same (table 3). How can the observable manifestation of a cause and an outcome be the same? Furthermore, process tracing assumes that the outcome is known and that there is one cause, making this approach questionable.

Fifth, the selection of cases is unconvincing. On one hand, one of the two cases (the TTIP) is not a legislative procedure and therefore provides limited insight into the mechanism at play in legislative negotiations. On the other hand, the second case is quite dated (from 2003), raising concerns about the current validity of its findings.

Generally speaking, the description of the method is a little light, there is a lot of theoretical discussion on process tracing and little on its concrete application in the context of this paper. 

Eventually, the discussion of the results is quite shallow. 'Basically, the author provides information without much rigor and it discusses some evidence for the involvement of some stakeholders and for disagreements between member states without proving the causal mechanism involved and how from initial triggers, entities (individual or institutional) engage in activities making the process longer.  This makes the conclusions rather minor, as it is not surprising that for such salient cases, some stakeholders try to be involved in negotiations and that some member states disagree. Moreover, again, it is not surprising that disagreements lead to longer decision-making than consensus They then conclude that this confirms the mechanism, but I don't really see how...

To conclude, I sincerely believe that the authors have the potential, particularly through their data collection, to make a valuable contribution to our understanding of the role of stakeholders in the EU decision-making process (yet, not solely to the legislative process).  However, this would require further reflection on the purpose, design of the paper, and implementation of the method.

Author Response

Comments 1: [First of all, the research's exact question or objective is unclear to me. The paper states that the interaction between the heterogeneity of Member States and stakeholder preferences leads to longer decision-making. On the one hand, this seems somewhat trivial, as it is fairly obvious that disagreement will lead to a lengthier decision-making process compared to a scenario where everyone agrees. On the other hand, it is unclear what the authors mean by “interaction”—do they mean that the heterogeneity of preferences among Member States and stakeholders occurs independently and when both occur it has a particular effect, and if so, what is exactly the cause that triggers the mechanism leading to the lengthy decision-making process?]

Response 1:

[Thank you for your thoughtful feedback regarding the clarity of the research question and the mechanism of interaction I propose in the manuscript. I agree with this comment. Below, I address your concerns point by point and outline the revisions I will implement in the manuscript.

1. The research question of this manuscript is: What is the causal mechanism about the interaction between opinions of interest groups and member-state preferences in the EU decision-making process? More specifically, this study examines the relationship between the variation in political actors’ preferences and the decision-making procedures, emphasizing the roles of interest groups and member states as critical stakeholders. While it might appear self-evident that heterogeneity could lead to delays, my study delves deeper into the specific mechanisms through which these factors interact to influence EU decision-making. I aim to go beyond the intuitive assumption of “more disagreement equals more delay” to provide an empirical and theoretical explanation of how heterogeneity in these dimensions coalesces to produce this effect. Therefore, I have rephrased the introduction to explicitly articulate the research question and objectives. This change can be found page 2, and lines 65-75 in the revised manuscript.
2. By “interaction”, I mean that the heterogeneity of stakeholders (including Member States and interest groups) does not simply occur independently but interacts in ways that amplify or modify their effects on decision-making duration. Specifically, I posit that: Member States’ heterogeneity in preferences creates foundational disagreements about policy directions. Interest groups’ preferences either exacerbate or mitigate these disagreements by influencing Member States’ positions through lobbying, coalition formation, or public pressure. This dynamic interaction triggers delays as the negotiation space becomes increasingly complex, requiring more time to reconcile diverse interests and preferences.
3. I have revised the manuscript to include a clearer explanation of this interaction. A new subsection has been added to the theoretical framework section, explaining the concept of “interaction” and outlining hypothesis so as to verify the causal mechanism leading to longer decision-making processes. I also have provided a concrete example of an EU policy case that illustrates this interaction and its effects on decision-making time. This change can be found pages 3-4, and lines 105-155 in the revised manuscript.]

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Comments 2: [However, in the rest of the paper, the authors seem to suggest that there is a causal link between the two factors (eg. line 210: "Moreover, interest groups’ demands affect member states preferences and their strategies in the EU decision-making process"), which implies the relationship between both is different. As I understand it, the point should be instead to investigate whether disagreements among interest groups affect the length of the EU legislative procedure by creating conflicts between Member States and increasing the transaction costs of reaching a decision. This is an appropriate mechanism to explore. I think the authors should reformulate the introduction along these lines, taking interest groups’ heterogeneity as the cause and examining the mechanism whereby this heterogeneity affects decision-making through its effect on member states' preferences and thereby disagreements.]

Response 2:

[Thank you for pointing this out. I agree with this comment and incorporate your suggestions in the introduction section. I understand that the phrasing in the original manuscript might have created ambiguity regarding the proposed mechanism. Below, I address your concerns and outline how I revise the manuscript accordingly.

1. To address your suggestion, I accordingly revise the introduction to focus on interest groups’ heterogeneity as the primary independent variable. The revised framing will emphasize the role of interest groups in shaping Member States’ preferences and creating conflicts. Also explain how these conflicts increase the complexity and transaction costs of reaching a decision, ultimately prolonging the legislative process. This change can be found pages 2-3, and lines 22--47 in the revised manuscript. Besides, I provide a detailed discussion of how interest groups’ heterogeneity translates into Member States’ divergent preferences and strategies in the theoretical framework. This will include references to relevant literature on interest group influence in EU policymaking. This change can be found page 3, and lines 139-155 in the revised manuscript.
2. I agree that examining whether disagreements among interest groups affect the length of the EU legislative procedure by creating conflicts between Member States and increasing transaction costs is a critical and relevant mechanism. My intention was to capture this dynamic interaction, but I recognize that the explanation requires greater precision. Specifically, interest groups’ heterogeneity leads to a diversity of demands and lobbying efforts, influencing Member States’ preferences. This, in turn, exacerbates disagreements among Member States, prolonging the negotiation process and increasing transaction costs. Thus, I reformulate the manuscript to make this mechanism explicit and ensure that the causal link between interest groups’ heterogeneity and the length of the decision-making process is clearly articulated. This change can be found pages 5-6, and lines 219-250 in the revised manuscript.
3. I also revise the mechanism section to include a step-by-step explanation of how interest groups’ demands influence decision-making outcomes. This will ensure that the causal link is transparent and methodologically robust. This change can be found page 7, and lines 317-321 in the revised manuscript.
4. In the case studies section, I explicitly demonstrate how interest groups’ heterogeneity influenced Member States’ preferences in the two selected cases, leading to prolonged decision-making. This will help substantiate the mechanism empirically. This change can be found page 8, and lines 324-340 in the revised manuscript.]

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Comments 3: [Furthermore, nowhere in the document does the author define what is meant by ‘stakeholder,’ nor do they distinguish between different types of stakeholders. This is a significant oversight, as the literature shows that different types of stakeholders (e.g., business vs civil society interest groups) can have varying impacts on the EU legislative process.]

Response 3:

[Thank you for pointing this out. I agree that the manuscript currently lacks a clear definition of “stakeholders” and does not distinguish between different types of stakeholders. To rectify this, I incorporate a detailed discussion of stakeholders, which includes internal stakeholders (e.g., EU member states) and external stakeholders (e.g., interest groups, distinguishing between business groups, civil society organizations, and other relevant actors, etc.). I also engage with existing literature that discusses the varying impacts of different stakeholder types on the EU legislative process. These changes can be found on page 2 and lines 74-77.]

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Comments 4: [Second, the paper does not discuss the existing literature on the duration of the EU decision-making process or position itself within this body of work. This lack of engagement with the relevant literature weakens the paper’s contribution and makes it difficult to understand how the research contributes to or differs from previous studies.]

Response 4:

[Thank you for pointing this out. I agree with your comments. Below, I outline the planned revisions to the manuscript to more comprehensively integrate and position my research within the relevant body of work.

1. I recognize that the current draft of the manuscript does not sufficiently engage with the established literature on the duration of EU decision-making processes. In particular, key studies examining the factors influencing legislative timelines, such as institutional complexity, conflict intensity, and transaction costs, will be reviewed and incorporated. This will include, for instance, studies on the role of institutional frameworks in shaping decision-making efficiency, such as Tsebelis (2002) on veto players and the implications for decision-making speed. Second, literature analyzing how intergovernmental negotiations and heterogeneity among Member States affect procedural timelines. Third, research on how external stakeholder pressures impact legislative dynamics and potentially contribute to delays. By situating the research within these established frameworks, I could more clearly demonstrate the novelty and relevance of my contribution, specifically the role of interest groups’ heterogeneity in influencing legislative timelines. These changes can be found on page 4 and lines 156-209.
2. To address the lack of clarity regarding the study’s unique contribution, I explicitly position the manuscript in relation to prior studies. Specifically, I highlight how the focus on the interplay between interest groups and Member States extends existing research, which has primarily centered on institutional or Member State-driven factors. I also discuss how the research provides a more granular understanding of how external stakeholders especially interest groups, can influence Member State preferences and, consequently, the length of legislative procedures. These changes can be found on page 18 and lines 813-837.]

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Comments 5: [Third, the paper lacks a proper mechanism linking the cause(s) (which is?) to the outcome through causal steps, as described notably by Beach and Petersen. This is crucial in process tracing. The current approach makes the process tracing shallow at best, as the causal mechanism triggered by the two (three?) causes is not clear. The paper does not break down the mechanism into entities and activities, nor does it discuss the contextual conditions or the different configurations of conflicts that may take place. For instance, arguably the two cases studied are rather salient ones, how does that matter for the "mechanism" at stake?]

Response 5:

[Thank you for your insightful comments regarding the causal mechanism and the application of process tracing in the manuscript. Below, I provide the detailed response and outline the planned revisions to address your concerns.

1. I acknowledge that the current manuscript does not adequately break down the causal mechanism linking preference heterogeneity to prolonged decision-making. To address this, I clearly define the causal mechanism in the revised manuscript. Drawing from Beach and Petersen’s (2013) framework for process tracing, I explicitly identify the entities (actors), activities (actions), and contextual conditions involved in the process. Specifically, the mechanism can be structured to detail the step-by-step process through which heterogeneity among interest groups and Member States generates disagreements, which in turn increases transaction costs, prolonging negotiations and legislative timelines. These changes can be found on pages 5-7 and lines 221-322.
2. The manuscript incorporates a detailed breakdown of how key entities (interest groups, Member States, EU institutions) interact and how their preferences align or conflict during legislative negotiations. For example, I have traced how specific interest group lobbying efforts influence Member State strategies and how these strategies, when divergent, increase bargaining complexities and delay consens These changes can be found on page 14 and lines 590-594.
3. As you pointed out, the salience of the two cases selected may affect the mechanism at stake, I will address this by explicitly discussing how the salience of policy issues influences interest groups engagement and Member State preferences. This will include exploring whether highly salient cases exacerbate heterogeneity and intensify conflicts, thereby affecting the duration of the decision-making process. In doing so, I also acknowledge the limitations of the case selection and discuss how the findings might vary in less salient cases. These changes can be found on pages 16-17 and lines 709-779.
4. I agree that the current process tracing approach could benefit from greater rigor. In the revised manuscript, I incorporate a more systematic application of process tracing by defining observable manifestations for each causal step, ensuring that these manifestations are clearly linked to the proposed mechanism, and strengthening the empirical evidence for each step in the process. These changes can be found on pages 5-6 and lines 219-249.]

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Comments 6: [Fourth the observable manifestations defined by the author are vague and not always clearly linked to the cause, and therefore not rigorous enough to test the mechanism. For example, what are the exact manifestations of the fact that ‘policy outcomes are shaped by the configuration of Member States and the demand of interest groups’, this is true for many different outcomes and, in one way or another, for all legislative files... The same is true for ‘Heterogeneous stakeholder views can shape decision-making outcomes by influencing negotiations between Member States in the Council’. The statement is too broad. Clearly, they ‘can’, and the thing is that they ‘could have’ even in some cases where this is not the case. Even if the link were clearer, these points would require observable manifestations. Finally, the last observable manifestation is actually that the expected relationship takes place, which is the whole point of the article. This is a process in itself, not an empirical manifestation of a process.]

Response 6:

[Thank you for your constructive feedback regarding the observable manifestations in the manuscript. Below, I provide a detailed response and outline the revisions I will make to strengthen the rigor and clarity of the approach.

1. I recognize that some of the observable manifestations are too broad and not directly tied to the causal mechanism, making it difficult to rigorously test the hypothesized relationship. In the revised manuscript, I have defined specific, measurable, and empirically grounded observable manifestations for each step of the causal mechanism. For example, instead of broadly stating that “policy outcomes are shaped by the configuration of Member States and the demand of interest groups,” I identify specific actions, statements, or behaviors that reflect this influence, such as: Member State proposals that explicitly cite interest groups demands. Patterns of coalition formation in the Council that align with specific interest groups lobbying efforts. Changes in draft legislation that can be directly linked to interest group interventions.
2. I agree that statements like “heterogeneous stakeholder views can shape decision-making outcomes” are too general and could apply to various scenarios. To address this, I refine the scope of the statement and link it to specific, traceable instances within the case studies. For example, I focus on observable manifestations such as: evidence of delays in Council negotiations caused by conflicting demands from interest groups. Secondly, the instances where Member States adopt positions influenced by domestic interest groups coalitions, as documented in official meeting records or interviews. These changes can be found on pages 5-6 and lines 221-249.
3. I acknowledge that one of the observable manifestations in the manuscript conflates the expected relationship with the mechanism itself, which undermines its empirical rigor. In the revised manuscript, I ensure that observable manifestations are not simply a restatement of the hypothesized outcome but rather distinct empirical indicators of the underlying causal process. For example: Observable manifestation: Stakeholder heterogeneity → Member State disagreement → extended negotiation rounds (evidenced by meeting records or procedural timelines). This breaks the mechanism into intermediate steps, with each step having its own empirical indicator. These changes can be found on page 6 and lines 268, 291, 318.

To ensure rigor, I disaggregate the mechanism into specific steps and define observable manifestations for each:

(1) Interest groups heterogeneity: Evidence of divergent public statements, lobbying efforts, or position papers from key interest groups.

(2) Impact on Member State preferences: Official documents, public statements, or negotiation positions showing alignment with stakeholder demands.

(3) Negotiation outcomes: Documented delays, procedural loops, or revised proposals reflecting conflict resolution efforts. These changes can be found on page 6 and lines 268, 291, 318.

4. For each observable manifestation, I tie it to specific evidence from the case studies (e.g., Council records, papers of interest groups opinion, and interviews). This could help distinguish between cases where stakeholder heterogeneity did or did not influence outcomes, addressing the concern that such heterogeneity “could have” an impact in all cases. Therefore, the revised statement could be: “Heterogeneous interest groups views are expected to shape decision-making outcomes by creating conflicts between Member States, as evidenced by divergent lobbying efforts documented in Council submissions, delays in negotiation rounds, and explicit references to interest groups demands in Member State negotiation positions.” These changes can be found on page 7 and lines 317-321.]

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Comments 7: [Additionally, there is no presentation of the third cause, which is only named and is actually discussed simultaneously with the outcome of the mechanism. Moreover, the observable manifestations of both are the same (table 3). How can the observable manifestation of a cause and an outcome be the same? Furthermore, process tracing assumes that the outcome is known and that there is one cause, making this approach questionable.]

Response 7:

[Thank you for highlighting the issue regarding the presentation of the third cause and its overlap with the observable manifestations of the outcome in Table 3. The third cause mentioned in the manuscript was indeed not adequately defined or distinguished. I acknowledge this oversight and provide a clearer presentation of this cause. In the revised manuscript, I distinguish between observable manifestations of the cause, the intermediate steps in the mechanism, and the outcome.

Specifically, I clearly define the third cause, including its conceptual boundaries, role within the mechanism, and its relationship to the other causes. I also provide theoretical and empirical justification for its inclusion as a distinct causal factor. For example: Cause (Interest groups heterogeneity): Evidence of conflicting demands in interest groups submissions or divergent lobbying activities. Intermediate Mechanism (Member State disagreement): Evidence of divergent Member State negotiation positions, as documented in Council records. Negotiation outcomes (Lengthy decision-making): Evidence of procedural delays, multiple negotiation rounds, or prolonged legislative timelines.

While traditional process tracing often assumes a single cause leading to an outcome, I understand that combining multiple causes can introduce complexity. In the revised manuscript, I justify the use of multiple causes by drawing on methodological literature that supports the exploration of causal complexity (e.g., Beach and Petersen’s discussion of causal configurations in process tracing). I also use a configuration-based approach to process tracing, explicitly discussing how the three causes interact and collectively contribute to the outcome. Besides, I specify that the outcome is known (e.g., the length of decision-making) and that the analysis is focused on tracing the causal mechanisms leading to that outcome. These changes can be found on page 8 and line 322.]

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Comments 8: [Fifth, the selection of cases is unconvincing. On one hand, one of the two cases (the TTIP) is not a legislative procedure and therefore provides limited insight into the mechanism at play in legislative negotiations. On the other hand, the second case is quite dated (from 2003), raising concerns about the current validity of its findings.]

Response 8:

[You are correct that the TTIP negotiation is not a legislative procedure but rather an international trade negotiation. Although TTIP is not a legislative procedure, it provides a valuable comparative lens to understand how stakeholder heterogeneity shapes negotiation dynamics in high-stakes EU decision-making processes. TTIP was included as an illustrative example of a complex, multilateral decision-making process influenced by interest groups heterogeneity and member state preferences. This complements the legislative case to illustrate broader decision-making patterns. In my next paper, I will substitute TTIP case with the European Green Deal legislation, which is a legislative procedure directly relevant to the study’s focus on EU legislative negotiations. This case provides contemporary insights into the role of interest groups and member state heterogeneity in prolonging decision-making. Please see the revision on page 9, lines 367-387.

While your concerns about the age of the EU-ETS legislative case are valid, I would like to provide a more detailed rationale for why this case remains critical to the study and how it aligns with the research question. Below, I explain why this case was selected, its relevance to the research objectives, and how its use contributes to the broader understanding of EU decision-making dynamics.

The second case remains highly relevant because it provides clear empirical data to trace the causal mechanisms under investigation. The study’s objective is to investigate how the heterogeneity of preferences among member states and stakeholders contributes to the length of EU decision-making processes. This case offers robust evidence of these dynamics, including: documented conflicts among member states stemming from preference heterogeneity; detailed records of stakeholder influence during the negotiation process; clear observable manifestations of how disagreements between stakeholders and member states prolonged the decision-making procedure. The availability of such comprehensive and detailed empirical data makes this case an excellent choice for process tracing, as it allows for a thorough examination of the mechanisms under study.

Although the TTIP case is not a legislative procedure, its inclusion complements the EU-ETS case by offering insights into how preference heterogeneity affects decision-making across different types of EU negotiations. Together, these cases provide a broader perspective on the impact of heterogeneity in both legislative and non-legislative contexts. The EU-ETS case focuses specifically on a legislative procedure, ensuring that the manuscript addresses the primary research question.

The two cases were selected to provide variation in context (one being a legislative process and the other an international negotiation), which enhances the study’s ability to generalize findings about preference heterogeneity and decision-making duration.

While the EU-ETS case is dated, its findings remain relevant to understanding contemporary EU legislative dynamics. The mechanisms it illustrates—such as the impact of preference heterogeneity on decision-making processes—are still applicable to the current institutional framework of the EU. Furthermore, the legislative procedure under study has not undergone fundamental changes since 2003, making the insights derived from this case transferable to more recent legislative contexts. Retaining the EU-ETS case also allows the manuscript to contribute to the broader academic literature by revisiting a well-documented legislative procedure, thereby connecting past and present understandings of EU decision-making processes.

The research question focuses on how the heterogeneity of preferences among member states and stakeholders contributes to prolonged EU decision-making. The EU-ETS case aligns directly with this question because it illustrates the causal mechanism by which preference heterogeneity leads to lengthy negotiations. It also demonstrates the interaction between interest groups influence and member state preferences in shaping the legislative process. It provides observable manifestations of how preference heterogeneity increases transaction costs and delays consensus-building. These changes can be found on page 9 and lines 375-387.]

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Comments 9: [Generally speaking, the description of the method is a little light, there is a lot of theoretical discussion on process tracing and little on its concrete application in the context of this paper.]

Response 9:

[The manuscript indeed includes substantial theoretical discussion on process tracing, which may have overshadowed the concrete steps taken to apply this method to the cases under investigation. In response to your comment, I enhance the methodology section by following content. First, I expand the methodology section to include a structured explanation of how process tracing was implemented. Second, I clarify the types of evidence used in the process tracing analysis and their relevance to testing the hypothesized mechanism. Third, I also include concrete examples of how process tracing was applied to the two cases, and illustrate its practical use in tracing the role of preference heterogeneity in shaping decision-making outcomes. Besides, I make the link between the evidence and the hypothesized mechanism more explicit by illustrating how each piece of evidence supports specific steps in the causal chain. Finally, the discussion will be revised to emphasize how the application of process tracing contributes to the understanding of causal mechanisms in EU decision-making. These changes can be found on pages 8-10 and lines 324-404.

Overall, these revisions could address your concern by providing a more robust and detailed description of how process tracing was applied in the manuscript. By incorporating concrete examples and clarifying the connection between the method and the research objectives, the revised manuscript could enhance its methodological transparency and rigor. I am confident that these additions will strengthen the study’s contribution to the literature on EU policy-making.  

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Comments 10: [Eventually, the discussion of the results is quite shallow. Basically, the author provides information without much rigor and it discusses some evidence for the involvement of some stakeholders and for disagreements between member states without proving the causal mechanism involved and how from initial triggers, entities (individual or institutional) engage in activities making the process longer. This makes the conclusions rather minor, as it is not surprising that for such salient cases, some stakeholders try to be involved in negotiations and that some member states disagree. Moreover, again, it is not surprising that disagreements lead to longer decision-making than consensus They then conclude that this confirms the mechanism, but I don't really see how...]

Response 10:

[Firstly, I acknowledge that the current discussion might not sufficiently demonstrate how the observed evidence supports the hypothesized causal mechanism. In the revised manuscript, I break down the causal mechanism into distinct steps, explicitly tracing how preference heterogeneity among interest groups and member states leads to a lengthier decision-making process. Besides, I provide a clear narrative linking the evidence from the two cases (e.g., interest groups opinions, member state disagreements) to specific stages in the mechanism (e.g., initial triggers, negotiation dynamics, and outcomes).

Secondly, to address the lack of detail on how entities (interest groups or member states) engage in activities that prolong the process, I highlight specific instances from the case studies where disagreements triggered additional negotiation rounds, procedural delays, or shifts in strategy, as well as use process tracing to map these triggers and activities systematically, demonstrating their contribution to the overall length of the decision-making process.

Thirdly, I provide a more rigorous analysis of the evidence, focusing on the exact role of stakeholder involvement in shaping negotiation dynamics, and how specific disagreements between member states were resolved or prolonged and their impact on the legislative timeline. I integrate additional primary evidence (e.g., meeting records, public statements) to substantiate claims about the causal mechanism. For example, in the TTIP case, I illustrate how divergent preferences among key interest groups influenced the negotiation strategy of member states, leading to extended discussions and procedural delays.

Finally, I agree that the conclusions must go beyond stating that disagreements lead to longer decision-making processes. The revised conclusion emphasizes how the findings contribute to the understanding of causal mechanisms in EU decision-making, particularly the interplay between interest groups, member states, and procedural dynamics. Meanwhile, I highlight any novel insights gained from the case studies, such as the specific conditions under which interest group heterogeneity and member state disagreements most significantly impact decision-making length. All these changes can be found on discussion and conclusion section with red line underscore.]

                                                                                                                            

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

My comments will be limited as I believe the manuscript has a fundamental problem with the labelling of variables it examines, the research question and hypotheses, as well as the structuring of the theoretical argument. From there, the manuscript demonstrates weaknesses on the epistemological and methodological level.

1.      The suggested title is of the manuscript is:

 The Causal relationship between heterogeneous preferences and the lengthy decision-making process of the European Union.

That formulation demonstrates the methodological inadequacy of the manuscript. If we are examining how preferences affect the length of the decision-making procedure, we can’t limit preferences to only “heterogeneous” preferences. The author formulates a directly directional relationship between “heterogeneous” preferences (leaving out the possibility of variation of preferences – the potential that they would be converging or homogeneous. With regard to the dependent variable, once again  the categories are limited. Procedure can be regular, short, of lengthy (indicative categories). Once again, only the lengthy procedure is explored which is methodologically inaccurate. The variables need to be defined across their categories. The research task of the manuscript should have been formulated as the relationship between member state preferences and decision-making procedure – and then formulate a directional hypothesis. Besides, the hypothesized relationship is quite intuitive and thus needs at best a demonstration through the empirical cases, rather than hypothesis testing.

2.      The manuscript is inadequately embedded in the literature and demonstrates a key deficiency in terms of under-theorizing state preferences. In The Choice for Europe (1998) Andrew Moravcsik posits member state preferences as derived from societal interests (influential domestic exporters and producers). The manuscript posits these two groups of actors as ontologically independent but allows interest groups and social actors to affect state preferences which are otherwise independently derived. The theoretical model for me is thus inadequate.

3.      There was a possibility for the manuscript to examine the forms of legitimacy with reference to effectiveness (output) not only process but that route was not. Why is length of procedure important, so that it was examined as the dependent variable in that research? What constitutes a normal, regular-length procedure? The manuscript could provide a baseline against which to defined what a “lengthy” decision-making procedure is. One with multiple loops?

4.      The manuscript does not explore whether excessive length alters the path of the ordinary legislative procedure, and how the two cases may present different, complementary or contrasting versions of lengthy procedures.  The case selection process is therefore underspecified. It is not clear why the two cases should be considered in parallel.

In summary, these are several introductory points but I believe without correctly implementing them the manuscript cannot adequately make the contribution to the literature it aspires to.   

  

Comments on the Quality of English Language

Minor revisions needed.

Author Response

Comments 1: [The suggested title is of the manuscript is: The Causal relationship between heterogeneous preferences and the lengthy decision-making process of the European Union. That formulation demonstrates the methodological inadequacy of the manuscript. If we are examining how preferences affect the length of the decision-making procedure, we can’t limit preferences to only “heterogeneous” preferences. The author formulates a directly directional relationship between “heterogeneous” preferences (leaving out the possibility of variation of preferences – the potential that they would be converging or homogeneous. With regard to the dependent variable, once again, the categories are limited. Procedure can be regular, short, of lengthy (indicative categories). Once again, only the lengthy procedure is explored which is methodologically inaccurate. The variables need to be defined across their categories. The research task of the manuscript should have been formulated as the relationship between member state preferences and decision-making procedure – and then formulate a directional hypothesis. Besides, the hypothesized relationship is quite intuitive and thus needs at best a demonstration through the empirical cases, rather than hypothesis testing.]

Response 1:

[Thank you for your detailed and insightful comments on my manuscript. I appreciate your constructive feedback, which has highlighted several key areas where my work can be improved. Below, I address your concerns point by point and outline the revisions I will implement in the manuscript.

1. I acknowledge that the exclusive focus on “heterogeneous” preferences in the manuscript limits the scope of my analysis. As you rightly pointed out, preferences can vary in nature and may also converge or exhibit homogeneity. To address this, I revise the manuscript to explore a broader range of preference configurations, including homogenous and convergent preferences, and their impact on decision-making processes. This adjustment will also involve refining the dependent variable to include categories such as “regular,” “short,” and “lengthy” procedures, ensuring a more comprehensive analysis across different decision-making outcomes. Based on your comments, I also revise the title of this manuscript as “The Role of Political Actors’ Preference Variation in the Decision-Making Process of the European Union”. Please see this change on page 1, and lines 1-3.
2. Your suggestion to reformulate the research task as an investigation into the relationship between member state preferences and decision-making procedures is well-taken. I redefine the research objective in the revised manuscript to examine this broader relationship and provide a clearer and more nuanced hypothesis. Furthermore, instead of testing a hypothesis that may seem intuitive, I focus on demonstrating the proposed relationship through in-depth empirical case studies, as you suggested. Please see these changes in the abstract and introduction section, namely, on page 1, and lines 8-19. Pages 1-2 and lines 22-77.
3. I agree that the manuscript currently lacks a clear definition of “stakeholders” and does not distinguish between different types of stakeholders. To rectify this, I incorporate a detailed discussion of stakeholders, which includes internal stakeholders (e.g., EU member states) and external stakeholders (e.g., interest groups, distinguishing between business groups, civil society organizations, and other relevant actors, etc.). I also engage with existing literature that discusses the varying impacts of different stakeholder types on the EU legislative process. These changes can be found on page 2 and lines 75-77.
4. I recognize that the manuscript insufficiently engages with the relevant literature on the duration of EU decision-making processes. To address this, I incorporate a comprehensive literature review to position my research within this body of work, explicitly discussing how my study complements or diverges from existing findings. Please see the change on pages 3-4, lines 104-154.
5. Your feedback on the lack of a well-defined causal mechanism is invaluable. I adopt a more robust approach to process tracing, explicitly breaking down the causal mechanism into entities and activities, and examining contextual conditions and conflict configurations. For example, I clarify how interest groups heterogeneity influences member state preferences and how these preferences, in turn, shape the length of the decision-making process. I also discuss the implications of case salience and its impact on the mechanism at play. Please see the changes on pages 4-5, lines 192-208.
6. I acknowledge that the observable manifestations in the current manuscript are vague and not sufficiently linked to the causal mechanism. I revise the observable manifestations to provide clearer and more specific evidence for each step of the mechanism, ensuring that they are rigorously defined and empirically testable. Please see the change on page 6, line 268; page 7, line 291; page 8, line 323.
7. You are correct that the TTIP negotiation is not a legislative procedure but rather an international trade negotiation. Although TTIP is not a legislative procedure, it provides a valuable comparative lens to understand how stakeholder heterogeneity shapes negotiation dynamics in high-stakes EU decision-making processes. TTIP was included as an illustrative example of a complex, multilateral decision-making process influenced by interest groups heterogeneity and member state preferences. This complements the legislative case to illustrate broader decision-making patterns. In my next paper, I will substitute TTIP case with the European Green Deal legislation, which is a legislative procedure directly relevant to the study’s focus on EU legislative negotiations. This case provides contemporary insights into the role of interest groups and member state heterogeneity in prolonging decision-making. Please see the revision on page 9, lines 367-387.

(1) While your concerns about the age of the EU-ETS legislative case are valid, I would like to provide a more detailed rationale for why this case remains critical to the study and how it aligns with the research question. Below, I explain why this case was selected, its relevance to the research objectives, and how its use contributes to the broader understanding of EU decision-making dynamics.

(2) The second case remains highly relevant because it provides clear empirical data to trace the causal mechanisms under investigation. The study’s objective is to investigate how the heterogeneity of preferences among member states and stakeholders contributes to the length of EU decision-making processes. This case offers robust evidence of these dynamics, including: documented conflicts among member states stemming from preference heterogeneity; detailed records of stakeholder influence during the negotiation process; clear observable manifestations of how disagreements between stakeholders and member states prolonged the decision-making procedure. The availability of such comprehensive and detailed empirical data makes this case an excellent choice for process tracing, as it allows for a thorough examination of the mechanisms under study.

(3) Although the TTIP case is not a legislative procedure, its inclusion complements the EU-ETS case by offering insights into how preference heterogeneity affects decision-making across different types of EU negotiations. Together, these cases provide a broader perspective on the impact of heterogeneity in both legislative and non-legislative contexts. The EU-ETS case focuses specifically on a legislative procedure, ensuring that the manuscript addresses the primary research question.

(4) The two cases were selected to provide variation in context (one being a legislative process and the other an international negotiation), which enhances the study’s ability to generalize findings about preference heterogeneity and decision-making duration.

(5) While the EU-ETS case is dated, its findings remain relevant to understanding contemporary EU legislative dynamics. The mechanisms it illustrates—such as the impact of preference heterogeneity on decision-making processes—are still applicable to the current institutional framework of the EU. Furthermore, the legislative procedure under study has not undergone fundamental changes since 2003, making the insights derived from this case transferable to more recent legislative contexts. Retaining the EU-ETS case also allows the manuscript to contribute to the broader academic literature by revisiting a well-documented legislative procedure, thereby connecting past and present understandings of EU decision-making processes.

(6) The research question focuses on how the heterogeneity of preferences among member states and stakeholders contributes to prolonged EU decision-making. The EU-ETS case aligns directly with this question because it illustrates the causal mechanism by which preference heterogeneity leads to lengthy negotiations. It also demonstrates the interaction between interest groups influence and member state preferences in shaping the legislative process. It provides observable manifestations of how preference heterogeneity increases transaction costs and delays consensus-building. These changes can be found on page 9 and lines 375-387.

8. I expand the description of the methodological approach, providing greater detail on how process tracing is applied in this context. The discussion of results will also be deepened to provide a more rigorous examination of the evidence, explicitly linking the findings to the causal mechanism and demonstrating how specific entities and activities contribute to lengthier decision-making Please see the change on pages 16-17, lines 709-779.]

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Comments 2: [The manuscript is inadequately embedded in the literature and demonstrates a key deficiency in terms of under-theorizing state preferences. In The Choice for Europe (1998) Andrew Moravcsik posits member state preferences as derived from societal interests (influential domestic exporters and producers). The manuscript posits these two groups of actors as ontologically independent but allows interest groups and social actors to affect state preferences which are otherwise independently derived. The theoretical model for me is thus inadequate.]

Response 2:

[Thank you for your thoughtful feedback regarding the theoretical framework and the conceptualization of state preferences. I appreciate your reference to Andrew Moravcsik’s The Choice for Europe (1998) and your critique of how the manuscript currently under-theorizes state preferences. Below, I address your comments and outline the revisions I will make.

1. I acknowledge the need to better engage with foundational works, particularly Moravcsik’s argument that member state preferences derive from societal interests, such as influential domestic exporters and producers. To address this, I incorporate a discussion of this theoretical framework in the literature review, positioning my work in relation to this established perspective. This includes an explicit acknowledgment of how my approach builds upon or diverges from Moravcsik’s mod Please see the change on pages 4, lines 171- 176.
2. You raise a valid point regarding the manuscript's treatment of interest groups, social actors, and state preferences. While the manuscript posits these groups as ontologically independent, I agree that this framing may have created ambiguity in understanding their interactions. Therefore, I clarify this by revising the theoretical framework to emphasize the interdependence between societal actors and state preferences. Specifically, I discuss how societal interests, including interest groups and social actors, shape and constrain state preferences in line with Moravcsik’s framework. Moreover, I provide a more nuanced explanation of how these actors influence the formulation of state preferences, without implying that these preferences are entirely independent or self-containe Please see the change on pages 4-5, lines 193-209.
3. To address your concern that the theoretical model is inadequate, I refine the model to explicitly incorporate the mechanisms through which interest groups affect state preferences. This will include: a detailed discussion of the pathways through which interest groups and domestic societal actors interact with government institutions to influence state preferences. An exploration of how different configurations of societal interests (e.g., competing or aligned preferences) shape the decision-making dynamics within the EU. Please see the change on pages 3-4, lines 139-155.]
4. In light of your comments, I revise the hypotheses to better align with the theoretical framework. Instead of treating state preferences as exogenously determined, I try to explicitly frame them as an outcome of societal-level interactions. This could provide a clearer link between the empirical analysis and the theoretical assumption These changes can be found on page 3 and lines 105-155. Besides, to strengthen the manuscript’s foundation, I engage with additional literature that builds on Moravcsik’s work, including more recent studies on the role of societal interests in shaping EU policy preferences. This could help contextualize my contributions and demonstrate how my study complements existing research. These changes can be found on page 4 and lines 169-175.]

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Comments 3: [There was a possibility for the manuscript to examine the forms of legitimacy with reference to effectiveness (output) not only process but that route was not. Why is length of procedure important, so that it was examined as the dependent variable in that research? What constitutes a normal, regular-length procedure? The manuscript could provide a baseline against which to defined what a “lengthy” decision-making procedure is. One with multiple loops?]

Response 3:

[Thank you for your constructive feedback regarding the examination of legitimacy and the dependent variable in my manuscript. Your insights have highlighted key areas where clarification and refinement are needed. Below, I respond to your comments and outline the revisions I will make to the manuscript.

1. You raised an important point about considering forms of legitimacy, particularly focusing on effectiveness (output legitimacy) in addition to procedural legitimacy. While the manuscript primarily examines procedural factors (length of decision-making), I now recognize that the implications of procedure length for effectiveness could have been explored further. To address this, first of all, I expand the discussion in the conclusion to connect procedural legitimacy with output legitimacy. Specifically, I discuss how prolonged decision-making may affect the effectiveness of EU policies, including their quality, enforceability, and stakeholder satisfaction. These changes can be found on page 17 and lines 781-787. Secondly, I include a literature-based reflection on how procedural legitimacy (e.g., inclusiveness and transparency) interacts with output legitimacy, drawing on existing EU governance studies. These changes can be found on page 18 and lines 813-837.
2. You rightly point out the need to justify why the length of the decision-making process was chosen as the dependent variable. To address this, I elaborate on the theoretical and practical significance of decision-making length, discussing its impact on the EU’s responsiveness, efficiency, and legitimacy. For instance, while longer procedures may enhance deliberation and inclusiveness, they could also delay critical policy responses or frustrate stakeh Please see the revision on page 18, line 822-828. Moreover, I also link the choice of this variable to existing literature on EU legislative processes, highlighting gaps in the study of decision-making duration and its broader implications. Please see the revision on page 18, lines 829-837.
3. I agree with your suggestion to define what constitutes a “normal” or “lengthy” decision-making process. To address this, I establish a baseline using empirical data on typical decision-making durations in EU legislative procedures (e.g., average timelines for ordinary legislative processes). I also distinguish between regular and lengthy procedures, referencing established thresholds in the literature or datasets, and provide examples of “multiple-loop” procedures to clarify the operational definition. Please see the revision on pages 2, lines 53-62.
4. I explicitly include a baseline for comparison, both quantitatively and qualitatively, to better contextualize the length of procedures examined in the manuscript. This could enhance the methodological rigor and ensure that the dependent variable is adequately operationalized. Please see the revision on page 2, lines 63-64.]

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Comments 4: [The manuscript does not explore whether excessive length alters the path of the ordinary legislative procedure, and how the two cases may present different, complementary or contrasting versions of lengthy procedures.  The case selection process is therefore underspecified. It is not clear why the two cases should be considered in parallel.]

Response 4:

[Thank you for your valuable feedback regarding the case selection and its connection to the research question. Your comments have highlighted critical areas for improvement in my manuscript. Below, I address your points and outline the steps I will take to revise the manuscript accordingly.

1. You raise an important point about examining how excessive procedure length may alter the path of the ordinary legislative procedure. To address this, I include a dedicated discussion in the analysis section, explicitly exploring how prolonged negotiations or procedural delays in the two cases affected the legislative process. This involves identifying whether and how deviations occurred from the standard ordinary legislative procedure (OLP) timeline, such as the emergence of new negotiation loops, delays in the trialogue phase, or changes in stakeholder influence. Please see the revision on page 2, lines 53-64. Meanwhile, I further elaborate on the implications of these deviations, focusing on how they may affect legislative outcomes, consensus-building, or institutional legitimacy within the EU. Please see the revision on page 18, lines 813-820.
2. You are correct that the case selection process needs to be better specified and justified. To address this, I include a detailed explanation in the methodology section, outlining the rationale for selecting these two cases. Specifically, I clarify why these cases are illustrative or representative of lengthy decision-making procedures and how they help address the research questio I also provide criteria for the selection, such as variation in policy salience, complexity, or the degree of stakeholder involvement, to demonstrate the relevance and comparability of the cases. Furthermore, I acknowledge any limitations in the case selection process and how these might affect the generalizability of the findings. Please see the revision on page 9, lines 367-387.
3. You point out the need to clarify how the two cases present different, complementary, or contrasting versions of lengthy decision-making. To address this, I include a comparative analysis of the two cases, highlighting the similarities and differences in the causes, processes, and outcomes of the lengthy decision-making procedures. For instance, I examine how the heterogeneity of preferences or stakeholder involvement manifested differently in each case, and how these factors contributed to procedural delays in unique ways. I also assess whether these differences provide broader insights into the variability of lengthy procedures across different types of EU policy areas. Please see the revision on pages 16-17, lines 710-779.

Thank you again for your insightful comments, which will significantly enhance the focus and rigor of the study. I look forward to implementing these revisions and submitting the updated manuscript for further review.]

Author Response File: Author Response.pdf