1 Introduction

Globalization and democratization are two of the most important developments in the international system that accelerated over the past decades. This development called for the creation and establishment of international institutions and global governance mechanisms that transcend the state system in order to cope with the complexities of our world. As a consequence, questions surrounding the nature and extent of an international democratic deficit have become one of the central issues of contemporary world politics. International institutions reacted to this critique by opening up to other actors than states, especially to civil society and business actors (Tallberg et al. 2016; Tallberg et al. 2013). This led to a plethora of studies that can be referred to as the “transnational turn.” The development that publics and scholars alike have so far mainly ignored is the internationalization and institutionalization of national legislatures and their possible normative and positive function in global governance.Footnote 1 On a factual level, there already exists a parliamentary dimension of global and regional governance. International parliamentary institutions have grown in number and significance in recent decades, leading some scholars to diagnose a completion of the global governance architecture (Johnsson and Jönsson 2016). Normatively, international parliamentary bodies that consist of national members of parliament (MPs) could enhance the democratic quality of global governance by representing citizens’ interest on the international stageFootnote 2 and controlling their government’s action within international organizations (IOs). On the one hand, this leads to a direct reduction of the complex principal-agent delegation chain of IOs which is described as democratically problematic by Vaubel (2006). On the other hand, national legislators could be able to obtain more reliable information about governmental action within IOs which serves as a mean to enhance democratic accountability and control within national institutions (Grigorescu 2015).

More than half a century ago, the British Member of Parliament (MP) Geoffrey de Freitas wrote in his function as one of the founders of the North Atlantic Treaty Organization Parliamentarians’ Conference: “The Conference was founded by parliamentarians for parliamentarians, and it will preserve its vitality only so long as it remains essentially parliamentary.” The conference – labelled “parliamentary assembly” nowadays – has preserved its vitality and still exists today. In addition, we can observe a movement towards the parliamentarization of IOs more generally. More and more parliamentary bodies with increasing competencies accompany governmental actions and decisions in IOs (Rocabert et al. 2014). The key components for the functioning of these international parliamentary bodies are the nationally elected MPs themselves. However, we know almost nothing about the incentives and disincentives for MPs to engage in these parliamentary institutions and international politics in general. This paper tries to fill this gap.

The general paradox from the view of a single parliamentarian is that in theory, there cannot be many reasons for an MP to be active outside national borders, especially in areas such as international organizations that voters do not follow greatly. The legislature’s function in the national democratic systems is to represent voters as much as it is to control the government, meaning that legislators are most directly tied to territorially defined policies (Slaughter 2009). In recent years however, potentially as an effect of increased international interdependence, legislators have started finding their voice on the international stage, thereby injecting new and different elements into politics and policies formerly dictated almost exclusively by the executive branch. Whereas this “trend of parliamentary internationalization” is analyzed from an institutional perspective both within national parliaments (role of foreign affairs committees, upgrades of the European Union committees) and on an international stage (emergence of regional parliaments), hardly any study considers the concrete behavior of national parliamentarians concerning international politics. The goal of this paper is to theoretically derive and empirically test explanations why individual legislators become members of international parliamentary assemblies.

The argument concerning international MP involvement put forth here scrutinizes the constituency level motivations that decrease the distance between citizens and decisions as well as party-level motivations to enhance the parliamentary control of governments. In order to build up my argument, I theorize how international engagement of MPs may be linked to these functions and come up with hypotheses on different incentives and disincentives of individual MPs and party groups to engage internationally.

This initial micro-level study of MP activity in international politics takes into account some complexities of multi-level governance. I contribute to the larger literature on rational involvement of MPs in international affairs and debates about the democratic deficit in global governance. In order to test my arguments about MP participation in international parliamentary organizations, I use data containing district and party level information about all 631 MPs of the 18th term of the German Bundestag (2013–2017) and their IPA involvement, as well as ten personal interviews with IPA members. I present some evidence that MPs from districts more exposed to globalization are more likely to become member of an IPA. In the larger picture, I deliver evidence that an important part of national political systems – its parliamentarians – react to the challenges of globalization and start to transform their roles and behaviors. Contrary, I find no evidence for party-level rationalities in IPA membership.

2 Concepts and functions of international parliamentary assemblies

A growing group of political scientists has started to acknowledge the democratic potential of IPAs. Remarkably, the initial study that is cited in the field is a report that was produced within an IPA, namely the Inter-Parliamentary Union report by Klebes (1990) about the “Development of International Parliamentary Institutions.” Since then, there are several explorative works about the democratic role and their (possible) influence (Cutler 2001; Kissling 2011; Šabič 2008a), some case studies about their internal functioning and their representation (Costa et al. 2013; Habegger 2010; Kraft-Kasack 2008; Marschall 2005), classifications and research agendas (Cofelice 2012; Šabič 2013) and first comparative empirical mappings of the field (Rocabert et al. 2014).

2.1 Defining international parliamentary assemblies

There is some scholarly debate how to define and delimitate the different international institutions where national parliamentarians meet and exchange.Footnote 3 Generally, authors speak of parliamentary assemblies, institutions, organs, fora, associations, and organizations. The broadest (and from a comparative perspective recently most often used) term is International Parliamentary Institution (IPI). However, it is rather used as a vague umbrella term for all kinds of international parliamentary gatherings (Cofelice 2012, p. 8), from institutions with a very strict institutional setup and real legislative power like the European Parliament to very loose, topic-specific networks of parliamentarians with no formal rights like the Parliamentarians for Global Action.

Along with most of the authors that investigate the parliamentary institutions that are the basis of my empirical analysis, I use the term parliamentary assemblies which are broadly defined as “transnational, multilateral actors which are constituted by groups of members of national parliaments” (Marschall (2005) as translated by Wagner 2013, p. 195). In contrast to the whole range of international parliamentary institutions, members of these assemblies consist exclusively of national parliamentarians assigned by the actual majorities in parliament (hence they are indirectly elected from the viewpoint of the IPA). These institutions are called international parliamentary assemblies by the parliaments itself, so I choose this stricter terminology.

To get a broad picture about candidate recruitment of different IPAs, I selected all seven IPAs to which the Bundestag contributes by sending members (and which existed at the beginning of the legislative term)Footnote 4: First, the Inter-Parliamentary Union (IPU) has a global focus and is informally linked to the United Nations. Second, there are three assemblies that have a regional focus on Europe; the newly established Inter-Parliamentary Conference on Common Foreign and Security Policy and on Common Security and Defence Policy of the European Union (EU) (IPC), the PA of the Organisation for Security and Co-operation in Europe (OSCE-PA), and the PA of the Council of Europe (PACE). Third, the last three IPAs consist of MPs from Europe and countries that share a sea (border) with them. These are the Parliamentary Assemblies of the North Atlantic Treaty Organization (NATO-PA), the Parliamentary Assembly of the Union for the Mediterranean (PA-UfM), and the Baltic Sea Parliamentary Conference (BSPC). All seven IPAs claim to fulfil the parliamentary representation and control function. A closer description of their development and their goals are presented in the appendix A.1 (Online Appendix available on the Review of International Organizations).

Table 1 contains the number of MPs for the different IPAs and Fig. 1 contains the spatial distribution of all IPA members by their home districts. In total, there are 64 membership places for the IPAs in the German Bundestag.

Table 1 Number of Bundestag seats in IPAs
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Fig. 1
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Spatial distribution of IPA members (own illustration)

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Besides the IPU, all IPAs have a regional focus and care about broad issues such as general cooperation, security, and democratization. They differ slightly in their frequency of meetings from four times a year (the PACE) to only an annual meeting (PA-UfM, BSPC). However, my qualitative interviews obtained that the overall work per MP in an IPA seems to be rather identical.

2.2 The paradox of IPA membership

There are two standard arguments about the “accepted wisdom” that international politics and international organizations are dominated by executives and bureaucrats, with parliaments wielding marginal influence (Raunio 2014). First, on the demand side, decision-making in international politics, especially foreign and security policy is characterized by diplomatic secrecy about states’ preferences and actions, it requires forms of flexibility and fast reactive capacity, and often requires national unity instead of the representation of different political and societal interest. Additionally, as Martin (2000) points out, the fundamental difference between domestic and foreign policies is the need to influence the activities of other countries. These points speak against a parliamentary role in international politics. Second, on the supply side, the goods that are predominantly produced in IOs (apart from trade benefits), are public goods, which makes free-riding the rational choice for MPs. Peace, security, health, democracy, or reducing transboundary pollution can hardly be used as a benefit for a specific district, which led to the fact that international issues were long interpreted as significantly less relevant for voters.Footnote 5

On the basis of that second argument, there cannot be much incentive for parliamentarians to be active outside national borders (Slaughter 2009). Parliamentarians are not “world citizens.” Voters expect from their representatives to focus primarily on local issues and national interests, rather than some “distant” problems (Šabič 2008a). This interpretation of MP duties was confirmed by German members of IPAs themselves, which repeatedly mentioned the depreciation of international activities by fellow party members and voters. Even the chairperson of the defense committee and member of the PA of the NATO and OSCE, MP Jürgen Hardt, stated that the PA position comes still with the suspicion of “traveling around too much.”

From a domestic politics viewpoint, democratic legislatures are tasked with four primary functions: linkage, representation, control/oversight, and policy-making (Kreppel 2014; Loewenberg 2011). Most legislatures engage in all four of these functions to some degree, but when it comes to international politics, the relative power of influence within each area varies. I suggest in the following two reasons why a bottom-up involvement of MPs in foreign affairs is functionally justified from the viewpoint of national legislatures.

On the one hand, the linkage and representation function needs channels to articulate and deliberate citizens’ preferences not only to national governments but also to the international environment, where national governments decide international policy. Furthermore, MPs could gain credibility and prestige from voters if they sparkle with first-hand information from IOs, which they obtained through the IPAs. Some authors highlight this representation function, especially under the lenses of reducing the democratic deficit of IOs (Marschall 2005). These normative foundations and political practices of the democratic nation-state may become more important as some observers believe that there is a “movement toward international democracy” (Trent 2007, p. 252). However, Slaughter sees this representation still underdeveloped, stating that IPAs rarely find themselves in situations where they can use the mechanism of soft power – information exchange, deliberation, persuasion – with much impact (Parízek 2017). I argue that there exist policies on the level of the regional constituency that have the potential to be handled internationally by parliamentarians, causing MPs to have rational incentives to signaling their constituency that their concerns will be handled at the international level. Immigration is only the latest example for the increased politicization of international problems in local constituencies.

On the other hand, the control and oversight function of legislatures is based on credible and independent information from international actions of governments. IPAs are seen as a means to fulfill these parliamentary functions on an international level (Habegger 2010; Šabič 2008a). The observer status of the IPU in the UN is an example of gaining firsthand information on governments’ action beyond the nation-state, which then could be scrutinized in parliament. The main resource for this control is information. Governments enjoy privileged access to information in international politics and have furthermore the means to blur their actions on the international stage at home. This tends to undermine the effectiveness of parliamentary control. Parties and committees may lack the information resource, especially between parties and with other parliaments, that IPAs can fulfill (Malang et al. 2017). Transnational parliamentary cooperation helps to overcome information asymmetries that typically emerge from international governmental action. This can happen on two levels within IPAs. On the peer-level, national parliaments can gain information about the preferences and positions of other governments by the respective parliamentary chamber during meetings in IPAs (Neunreither 1994; Raunio 2000; Slaughter 2009). On the institutional level, legislatures gain valuable first-hand information by the observatory inclusion of IPAs in the decision-process of international organizations and direct contacts to high-ranking politicians and administrators from IOs (Habegger 2010; Šabič 2008a).Footnote 6

3 Theoretical arguments about IPA membership

In order to generate explanations why parliamentarians and parties are eager to join International Parliamentary Assemblies, I develop a bottom-up explanation based on the general legislative functions and how IPAs could help to fulfil these functions.Footnote 7 I argue from the perspective of the actors in the legislature: the individual parliamentarians and the parties. I contrast two theories for the explanation of IPA activity: On the individual level, I expect vote-seeking behavior from parliamentarians. On the party level, I develop an information theory argument how the party role in the governmental process should influence the selection of IPA candidates.

3.1 Individual level factors: Representation and linkage

I want to explain why individual MPs aspire membership in an IPA. Therefore, I try to identify properties of MPs and their districts that deliver theoretically guided arguments for incentives and disincentives to join these institutions. I generally assume that legislators are selective in their behavior and that they are searching for ways to pursue their policy-goals and increase their chances of re-election (Zittel and Gschwend 2007). “Soft” evidence that IPA members think that voters might be interested in their IPA activity can be observed by looking at the communication of MPs during the 2017 election campaign. Out of the 54 German IPA members, 41 ran for re-election and 38 communicated their IPA activity on their website and linked social media channels.

I assume that legislators choose to belong to an IPA, which indicates that they view membership as serving some functions. This function can be the representation of constituency interests which increase the chances for re-election, as stated by the distributive theory of legislative organization (Shepsle 1978). I follow the cost-benefit explanation that was built to explain caucus membership of US congressmen by Miler (2011), voting in US Congress on trade relations and foreign aid (Hiscox 2002; Milner and Tingley 2011), and the membership in legislative membership organizations for US and European MPs by Ringe and Victor (2013). To begin with, almost all interviewed members of IPAs stated that there are generally more salient issues for MPs than international issues when it comes to re-election. Therefore, no general incentive to join IPAs exists for all MPs uniformly. However, I identify factors in the following that make it more likely for an MP to join an IPA, or as MP Hardt put it in the interview: “When you decide to opt for international affairs as your profile, you ask yourself, how does your constituency react? And if the constituency is more open to international issues or faces more problems due to globalization, you are more likely to join an IPA.”

Globalization has blurred the distinction between domestic and international issues, which “practically forces parliamentarians to become international actors if they wish to defend interests of their local constituencies adequately” (Šabič 2008b, p. 85). So, why are some districts more exposed to globalization than others? The first factor that could lead to variance in the international interest is the location of a constituency. If a district has a border to another nation-state, I assume that it is more likely that day-to-day challenges and opportunities of internationalization emerge. Hence, it seems plausible for legislators of these districts to engage in the representation of these constituency issues in the arena of IPAs. I hypothesize that if a district has a border to another country, the likelihood of an MP to become a member of an IPA increases. The same internationalization argument holds for the composition of a constituency. Some MPs in the interviews indicated that migration is nowadays one of the most salient topics on the district level. Whether migrants are interpreted politically positive as economic and social opportunities or negative as economic and cultural threat does not matter for my argument. A district with more migrated foreigners faces the opportunities and challenges of globalization on a daily basis. Hence, MPs from these constituencies should care about the representation of these issues to a higher degree. Therefore, the more foreigners live in a constituency, the more likely an MP is to join an IPA. A third district factor that captures the dynamics of internationalization is the rural-urban divide. Big cities attract much more international business, culture, universal education, and labor force than small villages and rural towns. Thus I hypothesize that MPs of urban districts will engage more likely in IPAs than MPs of rural areas.

In addition to district level factors, legislators face different constraints in joining international assemblies based on the ways how they were elected. First, the type of mandate should have an effect. In mixed representation systems, there are two ways of becoming an MP: winning the district or belonging to the part of a party list that gained the proportional elected seats. In line with Sieberer (2010), I expect that district MPs care stronger for their district concerns as do party list MPs. On a general level – since being part of an IPA seems rather distant from most district interests like unemployment or local infrastructure – district candidates face more disincentives to join such an institution. As mentioned earlier, participation in IPAs is seen by critics as a form of “parliamentary tourism” (Costa et al. 2013, p. 238). Šabič (2016) argues for US Congressmen that the constituents can be highly suspicious of foreign travels to institutions which do not directly represent their interests. For a mixed representation system like the one I observe in Germany, I therefore hypothesize that parliamentarians who are elected as direct candidates in their constituencies participate to a lower degree in IPAs.

Second, district MPs differ additionally in their constraints. I expect that the closeness of an election result and the economic performance of a district enables or constraints an individual legislator to participate in foreign policy. Ringe and Victor (2013) theorize the general tendency that MPs who are insecure about their prospects for re-election will choose a Constituency-Member role, meaning they try to formulate their profile as close to the district interest as possible. I assume that the more contested the last election, the more an MP will “stay resolutely parochial” (Slaughter 2009). I expect the same constraint for poor economic performance. High economic problem pressure at home decreases the likelihood of having time and arguments for engaging in international politics. Hence, the worse a district’s economic performance, the less likely the elected legislator will focus on foreign policy.

3.2 Party level factors: Oversight and control

Besides individual incentives and constraints to become active in foreign affairs, there exist also factors on the party level that should influence which parliamentarians are members of IPAs. I argued in the previous section that the main resource for controlling the government besides formal rights to do so is information (Krehbiel 1992). For parliamentary systems, Raunio (2009, p. 324) argues that this information function could be overestimated as parliamentarians, especially those of the governing parties, can easily get the information directly from ministries.

Taking upon Raunio’s assessment, I hypothesize different informational necessities for government and opposition parties. In contrast to presidential systems, most parliamentary systems including Germany are characterized by a fusion between governments and its parliamentary majority. This leads to a separation of the control and oversight function along party lines and not institutional lines (Döring 1995; Strom 2003). Although, by definition, the executive depends on majority support in parliament, in practice, the main cleavage is between the governing majority and the opposition (Finke and Dannwolf 2013). Governments have the possibility to grant information generated in the ministries especially to fellow parliamentarians. The opposition lacks this information channels (Lüddecke 2010, p. 198).

If controlling the government is mainly pursued by the opposition and at the same time the opposition lacks access to ministerial information that the governing parties have, I can argue that the value of IPAs is higher for the opposition than for majority parties. Accordingly, opposition parties have an incentive to select their best personnel to fulfill this task. My general assumption is – in line with the partisan theory of legislative organization (Cox and McCubbins 2007) – that parties can directly or indirectly influence the selection of IPA candidates. If controlling the government is salient only for the opposition, the most prominent members of the opposition should aim for this task. I therefore hypothesize that party leaders of the opposition are more likely to be active in international affairs than party leaders of the majority parties.

An additional factor that is supposed to influence the composition of IPAs on the party level is the previous expertise of legislators. In addition to party prominence, I expect that the best legislator for controlling the government can also be the one with most expertise in foreign affairs. Therefore we should see that for the opposition, the most experienced MPs in the field of international politics should be selected for IPA membership. I therefore hypothesize that international affairs experts of the opposition are more likely to be members of an IPA than MPs of the majority parties.

4 Operationalization

4.1 Data

For the empirical analysis, I compiled a new data set of all parliamentarians of the last German Bundestag (2013–2017). The basis for my data collection and the subsequent analyses is the cross-sectional list of all Bundestag members taken from the data website of the Bundestag. This data provides accurate information on the more general characteristics of all its members and, specifically, the activities in IPAs. The unit of analysis is the individual MP. The data comprises 631 parliamentarians of four parties, two parties in government and two in the opposition. The 18th Bundestag is rather unusual due to the ideologically very heterogeneous Grand Coalition cabinet consisting of centrist CDU/CSU and the social-democratic SPD contrasted by a rather small opposition formed by the GREENS and the leftist LINKE (Sieberer 2015).

4.2 Dependent variable: IPA membership

Basically, I am interested if an MP is member of an IPA. A first theoretical consideration is the question if MPs are really free to choose if they want to engage in IPAs and if everybody that wants to participate is allowed to do so. This selection and appointment procedure of candidates takes place behind closed doors in the first session of the newly elected parliament in every faction.Footnote 8 Whereas every parliamentarian is free to nominate herself to being part of an IPA delegation, there is a fixed number of participants for the IPAs which represents the political spectrum and majorities of the house (Klebes 1990; Lüddecke 2010; Šabič 2008a). For example, the CDU/CSU knows through its seat share in the house that they can fill six positions in the NATO IPA, whereas the SPD has four seats. I conducted a personal further inquiry to get information about the internal selection procedure. Three of the four partiesFootnote 9 of the present Bundestag answered my questions concerning IPA membership, two of seven IPA group chairsFootnote 10 answered my question about the relationship between IPA and committee selection, and the ten interviews with IPA members delivered further evidence. They indicated that in a first step, every MP is free to signal her interest in IPA membership. In a second step, the respective party leaders and functional committees apply a consensus oriented approach to appoint candidates that are “competent, experienced, and driven by personal interest.”Footnote 11 If the consensus approach does not work, there is a formal vote in the faction about the candidates.Footnote 12 However, in the personal interviews with the MPs, no one indicated that there was a formal vote in the faction. Rather, almost all answers followed the storyline that there was a vacant seat in an IPA and the respective MP signaled his or her interest and got the position. There is also no evidence for a clear hierarchy or sequencing between the appointment of the international committees like foreign affairs and defense (which could be more attractive and prestigious if one wants to engage in international affairs) and the IPAs. Additionally, once an MP is member of one IPA, she is free to take another IPA mandate. Taken together, I see no obstacle to treat IPA membership as an independent decision of every MP.

I use a dichotomous variable, international MEMBERSHIP, in order to measure if a parliamentarian is a full member of one or more IPAs. I also checked if it makes a difference to use full and standby members, however there were no significant differences. Additionally, I checked if an ordinal scaling of multiple memberships per parliamentarian would make a difference. However, only 10 MPs are member in two IPAs. My final dependent variable MEMBERSHIP therefore constitutes a less stratified, i.e., binary item that receives the value of 1 for one or more full memberships in an IPA (N = 54) and 0 for an MP without formal involvement in this form of international politics (N = 577).

4.3 Method: Logit models

The format of my dependent variable calls for a logit model. In order to address potential intra-group dependencies across the parliamentarians, I cluster the standard errors of the models’ covariates on the level of the party. Members of one party seem to be more similar to themselves as compared to MPs from other parties. Possible reasons are the slightly different procedures how to reach consensus, the active recruiting that differs within a party, the different emphasis on foreign and security policy between parties, and the distribution of list and direct mandates between parties.Footnote 13

4.4 Core explanatory variables: Individual incentives and party role

On the district level, I identified several positive stimuli for joining an IPA of the foreign affairs committee. BORDER captures if an MP comes from a district with a border to another country (N = 120) or not (N = 511). For every district, I additionally collected the percentage of UNEMPLOYED and the percentage of FOREIGNERS from the Federal Returning Officer’s data page. TOWN captures if a district consists of only one big town (or a part of it) (N = 144) or if more than one town and villages constitute the district (N = 487).

When examining why individual legislators engage in foreign policy the focus is on the type of mandate and the arising possibilities and constraints. The Federal Republic’s electoral system is a two-track proportional representation on the basis of universal suffrage for German citizens above 18. Half of the basic seats are allocated through relative majority vote in the single-member districts (SMD), and the other half through party lists in each of the sixteen states of the Federal Republic. MANDATE is coded 1 if an MP gained his mandate in an SMD (N = 299) and 0 for party list candidates (N = 332) which we directly coded from the Federal Returning Officer.Footnote 14 For a quick overview, all assumed connections and the respective operationalizations can be found in Table 2.

Table 2 Theoretical assumptions about the MP-level and party-level factors on the likelihood of IPA membership. (+): positive effect (−): negative effect
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I argued that there are several constraints that hinder parliamentarians’ foreign policy activity because there are more important district interests to represent. First, I identified the closeness of the race as one constraint. The higher the insecurity about re-election the more an MP will represent local interests. For the district candidates, I use the simple standard measure of (posterior) competitiveness in elections used in plurality contests, namely the difference between the winner and the second place finisher (Selb 2009). In line with Manow (2015), I define a difference of less than 10% between the elected candidate and the second place finisher as contested and thus insecure. This results in the variable SAFE DISTRICT which is zero for the close races (N = 98 for direct candidates only) and one for secure seats (N = 201 for direct candidates). For list candidates, a SAFE LIST is operationalized with Manow’s established list tier safety measure, which takes into account which place on the list of a given party guaranteed a re-election in all previous Bundestag elections (coded 1, N = 126, list candidates only) and not safe otherwise (coded 0, N = 206, list candidates only). If I do not split the analysis into list and district candidates, I use the combined variable SAFE SEAT of both measures of safety for each MP.

The coding of the variables related to the party-information argument is based on the information of the Bundestag website. Parliamentary LEADER identifies MPs holding one of the following offices: chairman of a faction or party secretary (N = 60). GOVERNMENT measures all MPs from the governing coalition (N = 504) as opposed to the two opposition parties (N = 127). Expertise in foreign affairs is captured by the information if an MP was already in one of the five international committees (PREVIOUS IC)Footnote 15 in the previous legislative period (N = 88) or not (N = 543) and if she was member of an IPA previously (N = 47) or not (N = 584).

I further control for several attributes of MPs. Their GENDER (1 = female, N = 230), a dummy to capture if it is their FIRST TERM (N = 217), the number of legislative periods (MATURITY) already served and if an MP obtained a university degree (EDUCATION = 1, N = 517) or not.

5 Analysis and results

I separate the explanation of individual MP participation in IPAs into five models in Table 3. Model 1 contains the individual explanatory variables for all MPs whereas model 2 and model 3 are based on the different type of mandate. The last two models 4 and 5 analyze the party effects for majority and opposition parties separately.

Table 3 Logit results for the dependent variable IPA membership
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5.1 Representation on the individual level

The globalization factors that should influence MPs positively to become members of IPAs show some of the theoretically deduced effects. I hypothesized that the general exposure to globalization, measured through the number of foreigners and the location of a district on the border of Germany, will increase interests in and problems of international politics and therefore also increase the probability of an MP to join. And indeed, Models 1–3 show a robust and substantial effect for the border dummy. The share of foreigners in a district shows also the hypothesized direction. Contrary to my expectations, MPs from rural regions join IPAs with a higher likelihood than MPs from bigger cities, the environment where we expected the realities of internationalization to be more salient.Footnote 16

To gauge the magnitude of the explanatory factors, I present the marginal effects of the binary variables in Table 4. Being an MP in a border district increases the probability of joining an IPA by 7.7 percentage points, as compared to non-border MPs. Another globalization driver for IPA membership was the share of foreigners living in a district. We can see in Fig. 2 that the marginal effects increase again with approximately the same magnitude when moving from districts with a low share to districts with a high share of foreigners. If I interact these effects, we can see in Fig. 3 that the predicted probability of a district MP from a border district with a high share of foreign population to join an IPA can increase by more than 20 percentage points compared to a district MP with no international exposure (= an average district MP not from a border district and a smaller percentage of foreigners in her district). Implicitly, these findings also deliver first signs that IPAs are interpreted by national MPs as serving for the representation of citizen’s interest beyond the nation state.

Table 4 Marginal Effects (dy/dx) for a discrete change from 0 to 1 (factor variables on the basis of the models depicted in Table 3)
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Fig. 2
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Predictive margins for the share of foreigners in a district

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Fig. 3
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Predictive margins of border district over the share of foreigners

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None of the hypothesized effects of the type of mandate has a significant effect on the likelihood of becoming a member in an IPA. That is, contrary to my argument that MPs with a greater degree of freedom will opt for IPA activities, the analysis shows that neither MPs with a list mandate nor with a generally safe election result will join IPAs more likely.

Model 2 and 3 use the same independent variables, but analyze their effects only for the subsample of directly elected district MPs for which we expect them to be stronger (Model 2) and the list MPs (Model 3). Whereas the border dummy and the share of foreigners keep their effects, I assumed that the worse the economic situation in a district, the less likely MPs will care about international problems. However, Models 1–3 do not find that negative connection. Contrary, for the district MPs that should be most likely to develop a constituency role and not join an IPA when the economy suffers, the effect is even reversed: More unemployment in the district increases the likelihood for being a member in an IPA.

5.2 Control at the party level

On the party level, the main driving force for explaining MP participation in IPAs was the different information endowment of government and opposition parties. I deduced that for opposition parties, the information generated and provided in IPAs is much more valuable than for majority party members. I expected therefore that opposition parties will send their most prominent and most appropriate personell to the committees in order to be able to control the government. For governmental parties, I do not expect such a party elite selection.

Models 4 and 5 introduce the same variables separately for governmental and opposition parties. In line with my theoretical expectation, party leaders of governmental parties are rather unlikely to engage in IPAs as can be seen in Model 4. Contrary, the variable that captures if an MP was part of an IPA or an international committee in the previous legislative turn is the strongest predictor for IPA membership in the current term for governmental parties. When looking at the marginal effects, we can see that previous IPA membership increases the likelihood of present membership by 12.2 percentage points.

For the opposition parties (Model 5), the effects are not significant and not always in the assumed direction. Party leaders have no higher probability of joining an IPA, contrary to my theoretical expectation. The expertise variables are also not as good in their predictions as for governmental parties. Previous IPA membership is not significant for the prediction of current membership, whereas a previous committee position has the same positive effect as for governmental parties. Taken together, opposition parties seem not to select their foreign affairs experts that are trained and experienced through the committee work, into the IPAs. This finding is contrary to my derived expectation that the opposition should select their most skilled personell into the IPAs to control the government on the basis of credible information.

Some remarks on the control variables: We can see an opposition-majority divide in education and maturity. Whereas IPA members of governmental parties are better educated than the non-members, opposition IPA members are longer in office and have significantly less likely a university degree than their opposition peers who are not part of an IPA.

5.3 Qualitative robustness and further avenues

To corroborate my findings from the analysis of the main effects, I try to disentangle some of the driving forces of IPA membership in the following with additional qualitative evidence. To this end, I contacted all German members of the IPAs for an inquiry about their motives to joining an IPA.Footnote 17 I was able to conduct ten semi-structured interviews with MPs from all political factions and out of all IPAs except the IPU.Footnote 18 The interviews took place during the heyday of the election campaigns to the 19th Bundestag between July and September 2017, so the MPs were able to report on whether they make use of their IPA membership within their current campaigns. Additionally, I was able to maximize variance on the independent variables, since I interviewed MPs both with district and list mandates, from border and non-border districts, and with varying personal characteristics such as party elite, seniority, and number of terms served in the IPAs. Appendix A.2 contains a list of the MPs interviewed.

Some trends manifested during the interviews. On the level of individual representation, about two thirds of the interviewed MPs were sure that their IPA membership does not increase their chances for re-election, neither in the constituency nor as appreciation by the party and materialized in a better place on the list. However, two reservations have to be made: Three MPs saw their IPA membership as specifically helpful for generating attention. This is especially the case for election observation activities of the OSCE, where members of this IPA gain a lot of media attention through direct reports from the Ukraine or the US. This prominent media coverage was generally interpreted as useful for re-election. The second reservation is that MPs from districts with signs of increased globalization awareness indicated that they use their IPA membership during the campaign in various ways. The three MPs in the sample that came from big cities all reported about specific policy forums during their campaigns. For such events, where foreign policy problems are discussed, they stated to have obtained an advantage by their first-hand information from the IPAs. Thus, information indeed seems to be an incentive, however, not on the party level to control the government. Furthermore, the electorate is perceived as more open to more complex explanations of current problems, or as Jürgen Trittin put it: “I have a district with a university environment, so I can discuss the roots of the problems.” The two MPs from border districts also hinted towards the usefulness of their IPA membership during the campaign. Whereas Peter Stein from the CDU simply put his BSPC affiliation on his flyers to “show the people what an MP is doing all the time for the region,” an MP from a German-French border district said that most of her electorate and she herself have a truly European spirit, so it “came naturally to engage in the PAER and the PA of the OSCE.” This also implies that the IPAs can be used to represent district interests.

One of the aims of the qualitative analysis was to gain some leverage about the possible endogeneity between an interest in international politics, the characteristics of the district and the characteristics of the MP, since there is no way to do this within the setup of my quantitative analysis. Whereas most interviewees agreed that MPs only develop an interest in foreign policy if there are no other dominant problems in the district, some MPs doubted my argumentation. Two MPs even stated that their interest in international affairs was exogenous to their district. They rather developed a “European spirit” through studying and working in different countries. Peter Stein even suggested that a certain type of international-minded politician has a better chance of winning a mandate in more globalized districts.

On the level of party control, MPs from all IPAs and from government as well as opposition parties agreed that they hardly use the information obtained during the meetings to control the government at home. According to them, the meetings generate two types of information. On the one hand technical or policy information which can be acquired in workshops, for example about Unmanned Aerial System or civil conflict prevention missions. On the other hand – and mentioned by almost all interviewees – IPA membership delivers information about the positions, preferences, worldviews, and internal cohesion of all the other parliaments represented in a given IPA. Naturally, this information is not used to control the government at home, rather it lifts the parliament in a privileged position compared to the national government because the MPs possess exclusive information. This was often mentioned as an important medium-term factor when it comes to questions about enlarging a given IO or questions of sanctioning. For example, even in times when the Russia-NATO council did not meet after the Krim crisis in 2014, the NATO PV still exchanged with the Duma. As an implication, all interviewed MPs from this IPA – besides the one from the Left party– agreed that they rather acted as “the German delegation” than as a fragmented group along party lines or the opposition-majority divide.

Another explanatory factor that received support on the control level by the interviews was the party expertise. Especially members of the NATO PV and the IPC mentioned as one reason for their membership their foreign affairs profile, which is also reflected by their membership in the defense or foreign affairs committee.

Additional factors that could not be verified to have an influence on the decision of joining an IPA are the type of mandate, the closeness of a race and party leadership. Even when asked directly, the responding MPs never attributed any effect to them. Additionally, no one confessed that the travelling was an incentive. To the contrary, Elvira Drobinski-Weiss only took the PACE mandate because they meet in Strasbourg, “in close distance to my constituency.”

Overall, the qualitative assessment corroborated the influence of the globalization variable border district, questioned the non-finding of the rural-urban divide in the statistical analysis and delivered further evidence that MPs use their IPA membership for generating expert knowledge, however not with the ultimate goal to control the government at home.

A future research avenue on the comparative aspects of parliamentary foreign policy in IOs was highlighted by a last consistent finding within the interviews: It was the perception of the MPs that the importance attributed the IPA meeting varies between countries. Two trends were mentioned several times: (1) smaller countries and countries that are not yet full democracies ascribe these meetings a much greater role, which is manifested in their willingness to host the meetings and really put a lot of effort into their organization. For example, the last four annual sessions of the OSCE PA took place in Minsk, Tbilisi, Helsinki, and Baku. (2) German MPs pointed out that IPA members of non-democratic parliaments put much more effort into their IPA role, which can be seen in the fact that often their exclusive parliamentary duty is to be part of an IPA. This emphasis opens the discussion about the democratic implications of IPAs for non-democracies. The empirical literature on IOs and lasting democratic consolidation points toward the positive effect of IO membership through external support for institutional development (Poast and Urpelainen 2015). One mechanism that Pevehouse (2002) develops is acceptance of liberalization by certain elite groups, either through a hand-tying process or through socialization. Here, IPAs can be an important supplement to the general IO effect. Since all German MPs hinted towards the importance of networking and exchange, these direct contacts could be a powerful instrument of socializing democratic values. Because IPAs themselves try to work like democratic parliaments, they can serve as a blueprint for parliamentary practices, a core element of democracy. A crucial component hereby is the relationship between MPs and the authoritarian regime at home. Is parliament somehow independent from the authoritarian leadership? Does the government at home desire democratic legitimacy through IPA membership? How are MPs assigned in general and to the IPAs? How do MPs from non-democratic regimes act in the democratic IPA realm? Do MPs really represent several and diverse interests, and can they lobby for their interests at IPAs? In this process of democratization, the IPAs could possibly play an important role which has to be analyzed further.

6 Conclusion

Democratic legitimacy beyond the nation state can only be achieved if the distance between citizens and international decisions is reduced and if the dominance of the executive in international politics is attenuated, at least by a better control of governmental action. International Parliamentary Assemblies are one way how national parliaments try to execute these tasks, thereby finding their voice on an international stage. The constituent parts of almost all IPAs are elected national parliamentarians. The present study focused on this individual foundation of IPAs and tried to explain which incentives and disincentives can explain individual membership in IPAs. I will now highlight selected findings and try to evaluate the democratic promises of IPAs on that basis.

Critics of IPAs state that these institutions are rather negligible in terms of influence and credible information on world politics. If this were true, one might expect that membership in IPAs is completely random. Contrary, if IPAs can offer legislators an important parliamentary venue in which they not only symbolically, but substantively stand for the interests of their constituents and their parties, we should observe that some attributes of MPs have an effect on their likelihood of becoming a member in an IPA. The data presented here not only provide a comprehensive survey of the most important IPAs for European parliaments but also present evidence that legislators’ choices about IPAs are shaped by their constituents. When looking at the involvement of MPs in IPAs for all members of the current German Bundestag, there is some support at the individual legislator level that IPAs are a component of constituency representation at the supranational level. This has implications for assessments of constituency representation, theories of the representative relationship, and the functioning of global democracy or global governance from a positive and normative viewpoint.

Let me highlight two findings on key determinants of the functioning of global democracy. First, the representation of district interests in IPAs can explain variance in the membership patterns of these organizations. I found some evidence that legislators who represent more internationally oriented districts (in terms of challenges and opportunities) are more likely to belong to an IPA. More concrete, the share of foreigners and the fact that a district is located at the border to another country increases the probability of a district MP to join an IPA by more than 20 percentage point. Second, the connection between government status of a party and the selected personnel for IPAs is quasi non-existent. Based on the assumption that opposition parties are much more eager to control the government and need credible information about international negotiations, I hypothesized that there should be a difference between government and opposition MPs who join IPAs in terms of expertise and internal party status. However, opposition parties are not more likely to send their party leaders to be part of an IPA compared to their governmental party peers. Additionally, expertise in terms of previous IPA or international committee membership has a positive influence on present membership only for governmental parties in the current Bundestag.

These findings are significant because they suggest a perspective on IPAs that has received little attention to date. Broadly speaking, the scholarly literature has emphasized two phenomena. Noting the predominance of governmental decisions and the increase of international treaties that are only approved by parliaments in their final version after international negotiations took place, some scholars have diagnosed a “decline of parliament” and a democratic deficit in international politics. They have concluded that national legislators have little incentives to engage in international politics and that parliaments have become marginalized institutions in terms of representing citizens on an international stage and controlling the government. My argument stresses an aspect that has largely been absent from this literature. The individual parliamentarian is the core component for the functioning of the IPAs. In this article, I have made a first attempt to disentangle the different incentive structures in the complex principle-agent setup MPs are facing. I assumed that only if IPAs truly help an MP to fulfill some of her parliamentary functions, she will choose to become a member. In other words, the significant effects of the internationalization measures on IPA membership tried to prove empirically that MPs ascribe a rewarding function to their IPA membership. Implicitly, my findings also suggest that IPAs have some potential to increase the democratic legitimacy of international institutions. However, I only found evidence for a meaningful pattern for the incentive to represent, not the incentive to control government.

Naturally, these results can only be a beginning, and much work remains to be done to explore more fully the roles and functions of IPAs in IOs. My findings open three perspectives for future research. First, the analysis of this article should be extended over countries and time to see whether the results are caused by special conditions of the current German Bundestag or reflect systematic variation. Especially a cross-chamber comparison promises to shed light on the different incentives posed by different political or electoral systems. Additionally, the German MPs emphasized the importance of these institutions for autocratic parliaments and governments. Empirical studies should focus on the question how IPAs can enhance democratization through the parliamentary elite. Second, future analysis could study the concrete actions of IPA members in terms of representing their citizens and controlling the government searching for the democratic legitimacy of these institutions from an output side. Are MPs really able to influence the discourse of international politics and can they ultimately put some of their citizens’ concerns on the agenda of IOs? Do members of IPAs challenge the government more often at home when international issues are discussed and decided upon? How could these new forms of democratic influence fit to different models of international or global democracy? Finally, how does IPA membership relate to other forms of parliamentary involvement like membership in international committees or parliamentary diplomacy, to core parliamentary action like voting behavior and to career paths of the MPs? After the recent surprising results of citizen involvement in international politics like the Brexit vote, the Swiss decline of the bilateral treaties with the EU or the general rise of nationalist parties there seems to be a swing back to emphasizing the importance of representative models of democracy and their influence on international politics. Thus, although IPAs have been understudied, there is little doubt that their persistence and proliferation in contemporary global democracy warrants renewed scholarly attention.