My research interests are in the areas of International Relations, peace and conflict studies and European Union politics, especially Common Foreign and Security Policy and EU Justice and Home Affairs. I am particularly interested in the interplay between domestic politics and international conflict.

Parliaments and Foreign Policy

For democracies, the scrutiny of the government’s foreign, security and defense policy has always been a challenge. For many years, I have studied the role that parliaments can play in ensuring democratic control over a state’s external relations. Together with Dirk Peters and Cosima Glahn, I have collected data on the role of legislatures in decision-making on the use of force in almost fifty countries. This dataset has allowed us to study what explains the remarkable diversity in legislative-executive relations but also their effects on military interventions. All in all, I found some (if modest) evidence for such a “parliamentary peace”: Countries where parliament needs to give prior approval for sending troops abroad are less likely to participate in a military intervention.

One way for parliaments to improve their position vis-à-vis governments is to work together in inter-parliamentary conferences and assemblies. As an accredited observer, I have been to some of them and interviewed parliamentarians on how they view inter-parliamentary cooperation.

In 2015, Tapio Raunio and I convened a workshop to study legislative-executive relations in foreign affairs more broadly. A selection of the papers from this workshop were published in a special issue of West European Politics in 2017.

Political Parties and Foreign Policy

I am interested in the party politics of foreign policy. External relations are not exempted from democratic politics. Political parties differ in their visions of the international order. Some support international law and cooperation, free trade and military interventions whereas others oppose them. Although once in government, political parties almost never implement their programs fully, they often make a difference and change a country’s course on the international stage. 

Together with Tapio Raunio at Tampere University I convened a workshop on political parties and foreign policy in Amsterdam in 2017 to explore the party politics in different countries and across different issue areas such as military interventions, European integration or development aid. A selection of the papers presented at the workshop is published in a special issue of Foreign Policy Analysis. 

I have been particularly interested in the party politics of military interventions. To compare political parties’ positions on military interventions in several countries, I initiated the deploymentvotewatch-projectAnna Herranz-Surrallés (Maastricht), Julie Kaarbo (Edinburgh), Falk Ostermann(Gießen) and I started collecting parliamentary voting data in France, Germany, Spain and the United Kingdom in 2017. Since then, many colleagues from additional countries have joined this effort and contributed data on additional countries. In 2019, we finalized the second version and in July 2021, we published a third version of the dataset with 1022 votes in plenaries for the period between August 1990 and December 2019 in Australia, Belgium, Canada, Croatia, the Czech Republic, Denmark, Finland, France, Germany, Ireland, Italy, Japan, Lithuania, the Netherlands, Romania, Slovakia, South Korea, Spain, Turkey, the United Kingdom and the United States of America. The third version was supported by a grant from the Gerda Henkel-Stiftung and can be found here. We published our findings in West European Politics and in a chapter for Delphine Deschaux-Dutard’s Research Methods in Defense Studies. We find that political parties systematically disagree over military interventions. Opposition is strongest at the far left and decreases as one moves along the left/right axis; support peaks at the centre-right and then decreases again at the far right.

The grant of the Gerda Henkel-Stiftung also allows us to carry out a pilot study on the party politics of international agreements. We are currently collecting parliamentary voting data on treaty ratifications in Canada, Finland, France, Germany, Italy, Slovakia, Spain, the United Kingdom and the USA. 

Tapio Raunio and I have also studied foreign relations votes in the European Parliament. We started with a study of 2750 votes between 1970 and 2014 and found that foreign policy is not different from other issue areas: voting occurs along party-political lines, rather than national ones; coalition patterns show that contestation follows the familiar left/right axis. In a next step, we are looking into EP votes on particular foreign relations issues: our analysis of the party politics of development aid will be published in the Journal of Common Market Studies; together with Maartje van de Koppel and Luis Pelaez, we are currently finalizing a manuscript on the party politics of transatlantic relations.

A comprehensive analysis of political parties, politicization and foreign policy can also be found in my book The Democratic Politics of Military Interventions.


International Norm Violations, Punishment and War

Together with Barbora Hola (criminology), Jan Willem van Prooijen (social psychology) and Wouter Werner (international law) I received a grant from the VU Vereniging for research on “International Norm Violations, Punishment and War”. The grant was used primarily to carry out two studies with Linet Durmuşoğlu, a Research Master student in social psychology. The studies examined how citizens judge the punishment of states for violations of international norms. The starting point is the idea that, akin to domestic societies, the international system is imbued with norms, ranging from human rights to the acquisition of weapons and the use of force. Norm violations of course occur and give rise to the question whether and how they should be punished. This question is interesting because the international system is different from domestic societies. Most importantly, there is no equivalent to the sophisticated criminal law system and the sanctioning power of the state on the level of the international system. The United Nations Security Council has a monopoly to authorize the use of force (other than in cases of self-defense), but it lacks coercive power of its own. In a similar vein, international courts and tribunals have remained dependent on states’ willingness to accept their jurisdiction and to support their proceedings, resulting in a highly selective practice of punishing international crimes. The UN and the international courts and tribunals can be seen as attempts to institutionalize third party punishment, i.e. the infliction of harm on a norm violator by an actor that is not directly affected by the transgression. Because the substitution of revenge, feuds, and vigilantism as common forms of second party punishment by a professional system of law enforcement has reduced levels of violence in domestic societies dramatically, the strengthening of the UN and the international courts and tribunals has been accompanied by hopes for civilizing inter-state relations and a concomitant decrease in warfare. Attitudes towards international punishment are therefore interesting because they indicate the degree of support for a key pillar of the liberal international order. The grant was used to carry out two survey experiments with more than 2.000 respondents in the US, Germany and the United Kingdom. These are the main findings of the studies: 1) Support for third-party punishment is higher than for second-party punishment not only in a domestic but also in an international context. Citizens thus support a key pillar of the liberal international order. 2) However, support for taking justice into one’s own hand is higher for international than for domestic norm violations, underlining that strengthening the United Nations and overcoming practices of self-help and the use of force without a mandate of the Security Council remains a challenge. The studies are currently rewritten into an article.


Here you can find some of the data that I collected. 

  1. Deploymentvotewatch

My biggest data gathering project is certainly  deploymentvotewatch, which was already mentioned above. It is a collaboration with many colleagues from 21 countries. We are collecting parliamentary votes on military interventions and, more recently, treaty ratifications in almost twenty countries. To learn more about this, please visit

2. PARLCON: Parliamentary veto powers over military interventions

The ParlCon dataset records the presence or absence of ex ante parliamentary veto power for all country years between 1989 and 2004 in which a country scored “9” or “10” on the “combined Polity score” (2006 version of POLITY IV) . 

A comprehensive documentation of the individual coding decisions can be found in: Wagner, Wolfgang, Peters, Dirk & Glahn, Cosima(2010), Parliamentary War Powers Around the World, 1989–2004. A New Dataset. Geneva Centre for the Democratic Control of Armed Forces (DCAF) Occasional Paper – No. 22.

The dataset can be found here

3. Attendance in Interparliamentary Assemblies

I see interparliamentary assemblies as important venues that support members of national parliaments in monitoring their governments. I collected data on the attendance of parliamentarians in the parliamentary assemblies of the Western European Union and of NATO. You can find the data for the NATO-PA here and for the WEU-PA here.

Again, you are welcome to use the data. If you do so, please cite the following publication:

Wagner, Wolfgang 2013: Who’s Coming? Attendance Patterns in the Parliamentary Assemblies of NATO and WEU,  in: Crum, Ben/Fossum, John Erik (eds.) Practices of Inter-Parliamentary Coordination in International Politics. The European Union and beyond, ECPR Press,, 195-213.

4. Expert survey data on policies towards Iran and North Korea

For the project Rehabilitation or Retribution? Cultures of Control and Policies towards Rogue States, Michal Onderco and I ran an expert survey on the policies of XY states towards Iran and North Korea at several periods of crisis, triggered by the discovery of nuclear activities such as nuclear tests. We were interested in estimating how accommodationist or confrontational these policies were. Results of the expert survey can be found here.

You are welcome to work with the data. If you do please cite the following publication as its source: Onderco, Michal & Wagner, Wolfgang (2012) Of Hawks and Doves: Mapping Policies toward Iran and North Korea. In The Nonproliferation Review, 19(2), pp.177-195

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