Introduction

The paediatric hospital “Bambino Gesù”, founded in 1869, has been one of the first Italian children’s hospitals. Since 1929, the hospital, located in Rome, has been an extraterritorial jurisdiction of the Holy See. In 1995, Italy and the Holy See signed a bilateral treaty concerning the relations between the Vatican paediatric hospital and the Italian national healthcare system. Due to its relevance, the two countries quickly signed and ratified the international treaty. The Italian parliament took only 92 days to approve a law to authorise the ratification of the agreement, which shortly entered into force in the Italian legislation. One might expect Italy to be generally quick at ratifying treaties with the Vatican. However, a bilateral agreement between Italy and the Holy See regarding tax evasion took almost nine years to be ratified, 3275 days to be precise.

Therefore, anecdotal evidence suggests that states’ treaty ratification process duration varies considerably, even when the parties are the same. Why is that so? Why are some treaties ratified faster than others? International Relations scholars have devoted much attention to treaty ratification, the act through which a state commits itself to the content of the treaty (Elsig et al. 2011; Koremenos 2005, 2016; Mansfield et al. 2002; Neumayer 2002; Goodliffe and Hawkins 2006; Bernauer et al. 2010; Kreps 2018). However, in our opinion, the existing scholarship has three limitations. First, almost all studies have focused on multilateral treaties, ignoring bilateral ones. Second, existing works use a cross-country perspective to better grasp the dynamics associated with cooperation worldwide or focus solely on the USA (De Laet and Scott, 2006; Kelley and Pevehouse 2015; Peake 2017). Third, to explain state treaty commitment, extant literature has not focused on cabinet’s ideology and its changes over time.

Our study addresses this threefold literature gap by exploring the politics of treaties in Italy. Through an original dataset,Footnote 1 containing 958 treaties approved by Italy between 1994 and 2022, we aim to investigate the determinants of treaty ratification. In particular, we address four associated questions: (1) Which treaties does Italy ratify? (2) How long does it take to ratify a treaty? (3) Why do some treaties take longer to be ratified? (4) What is the impact of ideology on this process? Such questions speak not only to the literature on international treaties but also to the debate on Italian foreign policy after the end of the Cold War. Some scholars argue that changes in foreign policy have characterised this period according to the ideological composition of the cabinet: while left-wing cabinets promoted a foreign policy approach more oriented to multilateralism, right-wing parties had a preference for bilateral ties with specific countries over multilateral cooperation (Carbone 2007; Andreatta 2008; Brighi 2013). We contribute to this debate by using treaties as a proxy for different points of view about foreign policy across Italian governments.

We find that Italy signs and ratifies much more bilateral than multilateral treaties, in most cases with other European states. Most treaties concern cooperation on Justice and Home Affairs, Science and Research, Security and Defence, and Economic issues. Italy tends to be slower at ratifying multilateral than bilateral treaties and highly salient treaties entailing substantial implementation costs, such as those regarding environments and human rights. Government ideology has a significant impact on treaty politics in Italy: shifts to the left speed up the process and vice versa. We find that such an effect is moderated in the case of multilateral treaties and treaties dealing with environmental and security issues.

The remainder of the article is structured as follows. In the first section, we explain the relevance of treaties and summarise the literature on treaty ratification. We then highlight the peculiarities of the Italian case and its treaty ratification process. Subsequently, we describe the treaties contained in our dataset. We then assess the impact of treaty characteristics and cabinets’ ideology on the duration of the ratification process through descriptive and inferential statistics. We conclude by summarising our findings and connecting them to the debate on international cooperation and Italian foreign policy.

The politics of treaty ratification

Treaties are a pivotal instrument of international politics that have attracted the interest of scholars in International Law and Political Science alike (Lantis 2009; Denemark and Hoffmann 2008; Hollis 2020).Footnote 2 Understanding international treaties is crucial, as their goals essentially involve instances of cooperation that would otherwise not occur due to either a collective action problem or expectations regarding dissonant future behaviour (Hollis 2020). In other words, treaties represent a form of commitment international actors make towards each other.

The life of treaties spans over four crucial stages: (1) the negotiation process, (2) the signature, (3) the ratification, and (4) compliance. We are interested in the intermediate steps, signature and, most importantly, ratification.Footnote 3 Ratification is the “international act whereby a state indicates its consent to be bound to a treaty” (UNTC). As Haftel and Thompson (2013) underline, ratification is crucial from both a legal and political perspective. On one hand, as the definition suggests, ratification is indeed a binding act for the parties. Several ratifications are usually required for a multilateral treaty to come into force. On the other hand, ratification roots the commitment in domestic institutions and enhances its credibility. Moreover, it is a public demonstration that the sides expect the treaty to be enforced. Ratification requirements vary markedly across countries and may constitute a significant obstacle in the process by imposing costs on political leaders.

Some studies have analysed the determinants of state treaty ratification, examining the probability of ratification and the time span between signature and ratification: a few on across multiple issue areas (Elsig et al. 2011; Lupu 2016) and the vast majority focusing on the most relevant international cooperation domains, including human rights (Hathaway 2007; Hafner-Burton et al. 2008; Goodliffe and Hawkins 2006), environment (Bernauer et al. 2010; Neumayer 2002), disarmament (Kreps 2018; Karlas 2023), trade (Haftel and Thompson 2013), and labour standards (Boockmann 2006). Besides “issue area” specific factors, scholars point to a series of general domestic and external factors affecting the extent of commitment. For example, democratic and democratising countries tend to be more committed than autocracies (Haftel and Thompson 2013; Moravcsik 2000). In addition, other studies underline that the global and regional patterns of ratification put pressure on other states to ratify the treaty too (Bernauer et al. 2010; Goodliffe and Hawkins 2006).

In our opinion, the literature on treaty ratification has three significant limitations. First, while most studies focus on multilateral treaties, only a limited portion analyses bilateral treaties (Peake 2017; Kreps 2018). Comparing multilateral and bilateral treaties is relevant as they entail different types of international dynamics. As the number of parties in a treaty increases, so it does the probability of observing collective action problems, including uncertainty about commitment and compliance (Axelrod and Keohane 1985). Therefore, we should expect bilateral treaties to be ratified more quickly than multilateral treaties. Kreps (2018) finds no significant difference between bilateral and multilateral disarmament treaties regarding the likelihood and duration of ratification. However, her study analyses only a limited number of disarmament treaties.

Second, the existing scholarship has an exclusively cross-national perspective. While a higher number of cases increases the generalisation of the results, it does not allow to delve into the specificities of single-country dynamics. Moreover, most existing single-case studies concern the USA (Lantis 2009; Peake 2017; DeLaet and Scott 2006; Kelley and Pevehouse 2015). We believe that extending the number of single-case studies to other small and middle powers would contribute to the understanding of treaty ratification as a phenomenon to analyse states’ foreign policy.

Third, very few studies have highlighted the role of ideology in explaining ratification commitment. Boockmann (2006) shows that left-wing governments are faster at ratifying International Labour Organization (ILO) conventions. Kelley and Pevehouse (2015) find that the process of treaty transmittal to the US Senate accelerates with Democratic presidents. DeLaet and Scott (2006) argue that partisanship has become an increasingly relevant factor in explaining votes to ratify arms control treaties in the US Senate after the end of the Cold War. This limited interest in the role of ideology is regrettable, given that recent research has shown its impact on states’ foreign policy behaviour across several domains, such as security and defence (Palmer et al. 2004; Ostermann and Wagner 2022), foreign aid (Thérien and Nöel 2000), and trade (Milner and Judkins 2004). Notably, leftists are associated with a more inclusive conception of domestic society that translates into an international relations approach based on multilateralism and respect for human rights. In contrast, rightists’ emphasis on the idea of hierarchy in domestic society turns into a foreign policy approach essentially aimed at the protection and prosperity of the nation first and foremost, tolerating the use of armed force when necessary (Rathbun 2004; Rathbun et al. 2016). Therefore, we might expect that the presence of a left-wing government in power leads to faster ratification processes, on average. This left–right divide should widen for multilateral treaties as well as for agreements that traditionally concern left-wing issues such as human rights and environment. Conversely, right-wing parties are expected to be more committed to treaties regarding right-wing issues such as defence and border protection.

The case of Italy

We concentrate our attention on treaty ratification in Italy after the end of the Cold War for three reasons. First, after the fall of the Berlin Wall, Italy experienced dramatic changes in its domestic political (and party) system that, according to many scholars, substantially affected its foreign policy. Second, the Italian Constitution guarantees parliament a minor but still relevant role in the treaty ratification process, fostering a stronger politicisation of this aspect of foreign policy. Third, Italy is considered a middle power, and results can be more generalisable than great or small powers. The focus on a single country inevitably reduces the scope of this work. However, it allows us to keep constant several intervening variables in exploring the duration of the treaty ratification process duration and the impact of treaty characteristics and cabinet ideology on it. In particular, in such a context, consistent cross-national variation in ratification procedures and national strategic culture could make a comparative analysis problematic.

Existing literature stresses how Italy's domestic politics and foreign policy are closely intertwined. During the Cold War, the bipolar competition on the global stage was reflected in the Italian party system with the clash between a centrist Christian Democratic party, Democrazia Cristiana (DC), and the largest communist party in Europe, Partito Comunista Italiano (PCI). The fall of the Berlin Wall decisively contributed to the disintegration of the PCI and the consequent crisis of the DC. In 1994, scandals regarding political corruption among the entire Italian political elite decisively disrupted the existing party system. A competition between centre-left coalitions, pivoted around PCI’s social democrat successors, and centre-right coalitions, centred around the charismatic figure of Silvio Berlusconi, rapidly emerged (Bartolini et al. 2004). These two coalitions alternated almost perfectly for approximately 20 years. The 2013 elections marked the decline of this latter party system and the emergence of the populist Five Star Movement (M5S) (Pasquino and Valbruzzi 2015). In response to this threat, a series of large coalition governments have been formed, led by the centre-left Democratic Party, bringing together parties that used to belong to the centre-left and centre-right coalitions. Eventually, after the 2018 elections, M5S came to power, first with the far-right League and then with the Democratic Party, only to leave its place for another large coalition cabinet, led by former ECB President Mario Draghi. It is also worth noting that since 1990, Italy has experienced three technocratic governments: Dini (1995–2016), Monti (2011–2013), and Draghi (2021–2022).Footnote 4

In this context, scholars have noted that centre-right coalitions were more interested in pursuing a bilateral foreign policy focused on Atlanticism without excluding bilateral ties with the USA and other countries with dubious democratic credentials, such as Russia and Libya; in contrast, centre-left governments adopted a multilateral and Eurocentric approach (Andreatta 2008; Carbone 2007). In this sense, ideology plays a crucial role in understanding foreign policy priorities and the approaches adopted by the different coalitions in power.Footnote 5 While it exists a large body of literature analysing the role of ideology in shaping Italian foreign policy concerning military missions abroad (Olmastroni 2014; Coticchia and Vignoli 2020) and the engagement in the EU (Andreatta 2008), the use of treaties to understand the interaction between ideology and foreign policy orientation is still neglected. We aim to fill this gap by analysing the treaty ratification process in Italy.

As suggested, the Italian parliament is involved in the complex and articulated Italian treaty ratification process. The Italian legislation differentiates between two types of treaties, entailing two treaty ratification processes, respectively: accordi in forma semplice and accordi in forma solenne. The former category includes agreements negotiated and signed by the government and later ratified through a signature by the President of the Italian Republic. In contrast, the latter encompasses those agreements that need the involvement of the Parliament (Raffiotta 2009). As stated in the Article 80 of the Italian Constitution, the Parliament must be involved in the process of ratification when international treaties “have a political nature, require arbitration or a legal settlement, entail change of borders, spending or new legislation”. In these cases, Parliament—Camera dei Deputati, the lower chamber, and Senato, the upper chamber—must vote and approve a law that authorises the President to ratify the treaty. The authorisation law is then published in the Official Gazette. Constitutional law scholarship considers the Article 80 as vague. Since most treaties imply the use of financial resources, it is hard to determine the political nature of the treaty or current legislation (Cafaro 2018).

To sum up, while the two main actors in the treaty ratification process in Italy are the government and the president, parliament has a non-negligible role. The government takes the lead as it has the authority to determine Italy’s foreign policy. It is interested in avoiding a parliamentary vote to reduce the duration of the entire ratification process, and the vague formulation of Article 80 provides a shortcut to do so (Cafaro 2018). The President may refuse to sign in case of a possible violation or incompatibility with the Italian Constitution or ask for the Parliament's authorisation for accordi in forma semplice. Therefore, the Parliament enters the treaty ratification process only under certain circumstances, upon the decision of the other two actors.

Moreover, the government controls the parliament through its majority, further restricting the parliament’s margin of manoeuvre. Against this background, parliament took part in the ratification process in several treaties signed by Italy and, following the aforementioned constitutional norm, usually in the most relevant ones. As described above, parliamentary approval is necessary for treaties with a “political” nature. Within such admittedly vague category have fallen all the most relevant bilateral and multilateral treaties Italy has signed. To conclude, it is fair to say that parliament had a say on treaties that matter the most for Italian foreign policy.

Finally, its peculiar position in the international system makes Italy a case worthwhile to explore. Despite the difficulties in categorising states as middle powers (Holbraad 1971), Italy is considered by the existing scholarship to belong to this category of countries. Whether middle powers conceptualisation is problematic, key characteristics have been identified by the extant scholarship. Middle powers are generally stable democracies, egalitarian, and at the core of the global economy (Jordaan 2003). Moreover, Holbraad (1971) claims that middle powers behave differently depending on the nature of the international system. In a bipolar system, middle powers are supposed to ally with one of the two superpowers, possibly reducing tensions between the two greatest actors. In a multipolar system, middle powers may play a more relevant role in international politics. Indeed, Italian foreign policy during the Cold War has been characterised by low profile and passiveness (Brighi 2013; Santoro 1991). Italy developed a more assertive and active foreign policy after the fall of the Berlin Wall and the consequential detachment of the US grip on Western European countries (Verbeek and Giacomello 2011). In particular, Italy’s increasing involvement in military interventions since the 1990s provides evidence for such predictions (Coticchia and Vignoli 2020). At the same time, Italian policymakers never questioned the country’s commitment to multilateralism and international cooperation through regional and global organisations such as the United Nations, NATO, and the EU (Coticchia and Vignoli 2021). Therefore, all else equal, Italy fit within the conceptualisation of middle power in International Relations. Its never-ending balancing effort between the quest for an autonomous foreign policy and incentives to be a reliable multilateral partner should be reflected in its treaty politics, producing a great extent of variation in terms of treaty type, issue, and partner. Despite some peculiarities, its democratic nature, its role at the core of the global economy, its institutional system—a parliamentary republic with two chambers—and its foreign policy make the Italian case a relevant and comparable case study.

The treaties

To test the impact of government ideology on treaty commitment in Italy, we collected data on the treaties ratified through parliamentary approval between 1994 and 2022, from Legislature XII to XVIII. In total, our dataset includes 958 treaties.Footnote 6 We gathered data from the institutional website of the Italian lower chamber (Camera dei deputati) and the official web portal providing access to all laws approved in Italy (Normattiva). As we previously suggested, the treaties undergoing parliamentary approval represent only a fraction of all treaties signed and ratified by Italy. However, they are a numerically significant portion: almost 40% of all the treaties approved after 1994.Footnote 7 As suggested, they also tend to be more relevant with respect to those that do not require parliamentary approval. Our list includes treaties of the utmost significance for international cooperation (e.g. the Kyoto Protocol on Climate Change) and Italy’s foreign policy (e.g. the Treaty of Friendship with Libya). Our focus on parliamentary-approved treaties also allows us to effectively test our arguments regarding the impact of government ideology and treaty characteristics in determining the ratification process's duration. The scheduling of debates and votes is established by the government of the day, together with the Presidents of the two Chambers. Therefore, the decision to delay the parliamentary approval can be considered a proxy for the salience attributed by the cabinet to a specific treaty based on ideological preferences and the characteristics of the treaty itself.

We distinguish treaties by type, partner, and issue. Regarding the type, it is possible to broadly differentiate between bilateral and multilateral treaties. To put it bluntly, while bilateral treaties involve two parties, multilateral treaties involve more parties. However, we believe it is appropriate to differentiate between six sub-categories within these two categories. Within the group of bilateral treaties, we distinguish between those made with another state, those made with an institution (e.g. UN, WHO), those made between an institution whose Italy is a part of and another state (e.g. EU with South Korea), and those made between an institution whose Italy is a part of and another institution. Among the multilateral treaties, two further groups of treaties emerge: those with multiple states (e.g. the Comprehensive Nuclear Test Ban Treaty) and those between an institution Italy is a part of and a group of states.Footnote 8

Figure 1 shows the distribution of the treaties by type. Bilateral treaties with another state are the majority in our sample: 594 (62%). The other types of bilateral treaties are not nearly as frequent: in our dataset, we have 78 treaties between an organisation and a state, 49 treaties between Italy and another organisation, and 11 treaties between two organisations. Multilateral treaties involving multiple countries as individual actors are 218, accounting for 22% of the total. Multilateral treaties between an organisation and multiple countries are only 8 in total.

Fig. 1
figure 1

Number of treaties by type

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As Fig. 2 shows, within the category of bilateral treaties with other states, the vast majority (264) are made with fellow European states (44 per cent), followed by countries located in Asia (110), Africa (87), and the Americas (North, Central, and South) (100). Notably, Russia has been the preferred bilateral partner, with 19 treaties, followed by France and Switzerland, two bordering countries. Some Eastern European and Western Balkan countries, including Ukraine, Moldova, and North Macedonia, rank high among Italy’s top bilateral partners. Italy also ratified several treaties with countries with strong cultural ties, such as Argentina and Brazil, and Arab countries like Qatar, Algeria, and Tunisia.Footnote 9

Fig. 2
figure 2

Number of bilateral treaties by other parties’ region

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Table 1 .
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Furthermore, we distinguish agreements by their issue or, in other words, by the topic they deal with. We developed a 16-issue categorisation that is partially drawn from the division in the chapter reported in the United Nations Treaty Collection and partially from the peculiarities of the Italian case. The issue categories are the following: “Agriculture, fisheries and food”, “Culture and Tourism”, “Diplomacy”, “Economics and Finance”, “Energy”, “Environment”, “General”, “Health and Drugs”, “Human Rights”, “Justice and Home Affairs”, “Science, Research and Education”, “Security and Defence”, “Trade and Development”, “Transport and Communication”, and “Welfare”. Some categories are rather self-explanatory, others less so. The latter group includes, for instance, “diplomacy”, covering all the treaties concerning diplomatic activities, privileges, and immunities (as well as those concerning bordering issues. “General” is a category that encompasses all the treaties that regard general cooperation (including EU treaties such as Maastricht) but also accessions of states to institutions (e.g. the accession of Croatia to the EU or North Macedonia to NATO). “Other” is a purely residual category, covering issues such as succession or recognition of marriages.

The issue area with the most significant number of treaties in our sample is justice and home affairs (121, 12 per cent of the total), including many bilateral treaties of judicial cooperation with other countries and agreements on extradition. Science, Research, and Education, Security and Defence, general, and Economics and Finance treaties follow with more than 100 treaties each. Figure 3 shows the complete breakdown of treaties by issue area.

Fig. 3
figure 3

Number of treaties, by issue

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Ratification duration, ideology, and treaty characteristics

On top of this, we want to investigate the determinants of the duration of the treaty ratification process, considering it as a proxy for commitment. We measure it as the number of days spanning between the date of the treaty signature and the date of the publication of the law related to the ratification and execution of the treaty, which tends to rapidly follow the second approval vote in Parliament.

The average duration of the ratification process for the treaties included in our dataset is 1,315 days, approximately three and a half years. However, the variance in the variable is considerable, as it ranges between a minimum of 31 days and a maximum of 8,502 days, more than twenty years. Figures 4 and 5 break down the distribution of the variable measuring the ratification duration by treaty type and issue, respectively.

Fig. 4
figure 4

Duration of the ratification process, by type

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Fig. 5
figure 5

Duration of the ratification process, by issue

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Multilateral treaties involving Italy and multiple states are by far the ones that take more time to get ratified, with a mean of 1,732 days and numerous outliers. In line with existing theories of international cooperation, such a longer ratification process can be attributed to a collective action problem among states. As the number of parties involved in a treaty increases, uncertainty regarding compliance and commitment also increases. In other words, if one state does not believe other states will commit to a treaty, it is less likely to commit itself. However, other domestic explanations may account for longer ratification delays for treaties involving multiple parties. One could be the necessity of time to adjust policy before ratifying. Many of these treaties concern relevant policy areas, such as environment (42) and human rights (25), that may set standards and goals requiring the domestic approval of new laws or the adaptation of existing ones to be met. Environment and Human Rights are indeed among the issue area categories with the longest ratification processes. Moreover, as a middle power, Italy has strong incentives to participate in these treaties that go beyond the ideological leaning and political goals of the government of the day. Therefore, cabinets may not perceive such treaties as part of their foreign policy agenda and prioritise ratification.

However, it is worth noting how bilateral treaties with other states might also take relatively long to ratify: 1,249 days on average. While the difference in the average ratification duration concerning treaties with multiple states is significant, this result is somewhat surprising. One potential explanation consists in the higher extent of contestation that these treaties can generate, depending on the characteristics of the other party. The delay is partially the product of a considerable number of outliers. The vast majority of treaties about Security and Defence, Science, Research, and Education, Economics and Finance, and Justice and Home Affairs consist in bilateral cooperation agreements between Italy and another state. Treaties in these four areas present rather short ratification duration processes on average, ranging between 1181 days for Economics and Finance and 1408 days for Justice and Home Affairs. In summary, the above-average ratification processes for treaties between Italy and another state seem only an exception.

The ratification duration significantly decreases when an organisation is part of the treaty. Treaties signed by international organisations that Italy is a member of take, on average, between 1021 and 1025 days to get ratified. The presence of an international organisation contributes to reducing the problems associated with uncertainty about other actors’ commitment. Notably, the treaties between Italy and organisations are the fastest to be ratified, with only 774 days on average. These treaties often concern low political issues such as establishing headquarters in Italy or privileges and immunities for the organisation’s personnel. Unsurprisingly, the category “diplomacy” is also an issue area with the shortest ratification period (805 days).Footnote 10

As we argued earlier, one of the core objectives of this article is to examine the impact of cabinets’ ideology on treaty ratification to assess continuity and changes in Italy’s foreign policy. We measure government ideology as the governing parties’ left–right position—as taken from the variable “lrgen” of the Chapel Hill Expert Survey (CHES) database, ranging between 0 (left) and 10 (right) (Seth et al. 2022)—weighted by their number of seats in the parliament’s lower chamber controlled by these parties.Footnote 11 From such ideology scores, we developed a variable that captures cumulative ideological shifts during the ratification process and their overall direction. The higher the values in the variable, the more and the more significant the shifts to the right that occurred in this period and vice versa.Footnote 12

The choice of such a variable is primarily based on the necessity of adopting a treaty-level analysis unit. In fact, we cannot segment the duration of the ratification process into a larger unit of analysis, such as years or months, for two reasons. First, both signature and ratification occur on precise days; consequently, any form of aggregation of this span would be an approximation. Second, more than one government can alternate in power in any individual year and even in individual months. This is especially true in Italy, which has Western Europe's shortest average government duration (Curini and Pinto 2017). The decision to focus on cumulative shifts rather than cumulative positions is grounded on both theoretical and empirical reasons. On the one hand, we believe that changes in government are more decisive than governments’ positions per se in explaining potential delays in ratification: delay may emerge in fact from alterations in government preferences rather than from preferences themselves.

We employ event history analysis as a method of analysis, as it is specifically designed to explain phenomena spanning across time (Box-Steffenmeier and Jones 2004). Among the various event history models, we choose the Cox proportional hazard model. This model does not make any assumption regarding the relationship between time and probability of observing the event, in our case treaty ratification. The Cox proportional hazard model has been widely used to explain variation in treaty ratification duration across states (Elsig et al. 2011).

Table 1 shows the results of the four models. We report the coefficients that must be exponentiated to be interpreted. Models 1 and 2 assess the impact of cumulative shifts in government ideology between treaty signature and ratification on the duration of the process. We expect that larger cumulative ideology shifts to the left lead to shortening the ratification process. Model 3 investigates the presence of an interaction effect between government ideology and the type of treaty, focusing on multilateral treaties. Considering both the debates on the relationship between ideology and foreign policy and change and continuities in Italian foreign policy, we should expect cumulative shifts to the left to lead to even shorter ratification processes in the case of multilateral treaties, increasing the overall impact of partisanship. Model 3 examines the relationship between the direction of shift and treaty issues, considering four extremely relevant issues associated with the left (Human Rights and Environment) and the right (Justice and Home Affairs and Security and Defence), respectively. We assume that the impact of cumulative ideological shift is amplified for left-wing issues and reduced for right-wing issues.

In all models, we control for the effect of cumulative changes in the number of cabinets and elections. We expect that increases in both these variables are associated with a longer ratification process. Moreover, we control for all treaties ratified during the legislature through a dichotomous variable. We expect this variable to positively impact ratification likelihood since this period corresponds to the endpoint of the analysis, and we do not consider treaties that are not yet ratified. However, we deem as relevant to include it in the model, considering the seismic change produced by the 2018 elections and the consequent rise to power of the populist M5S. Fixed effects for treaty issue are used in Models 1 and 3, and fixed effects for treaty type are used in Models 2 and 4.Footnote 13

Models 1 and 2 indicate that the likelihood of ratification significantly decreases by 3.8 per cent as cumulative ideological difference increases by one unit. In other words, in line with our expectations, the more government ideology moves to the right, the longer treaties take to be ratified in Italy. The Dublin Convention on Extradition between the European Union and Member States was one of the slowest treaties to be ratified in our dataset with 8330 days, almost 23 years. Signed under the centre-left Prodi I cabinet, it has been ratified under the Conte I government, composed of the populist Five Star Movement and the nationalist party League. During this period, we saw a prevalence of right-wing and centrist cabinets over left-wing counterparts and, consequently, the account the cumulative ideology shift score is around 3.5.

The interaction term in Model 3 is positive and significant. This means that multilateral treaties moderate the effect of cumulative ideological shifts. Whether the cabinet ideology shifted more to the left or the right during the process matters less when ratifying treaties involving multiple states. Specifically, the impact of cumulative ideological differences is reduced by 11%. This finding challenges the conventional wisdom that left-wing governments pursue a more multilateral approach to foreign policy compared to right-wing counterparts, in Italy as well as elsewhere. Model 4 offers a mixed picture regarding the interaction between cabinet ideology and treaty issues. Only Environmental and Security and Defence treaties seem to significantly affect the relationship between government ideology and the treaty ratification process. However, while we expected right-wing issues such as Security and Defence to decrease the left–right gap in treaty ratification duration, we could not foresee that the same occurred for Environment, a left-wing issue. A potential explanation for this latter result may lie in the relevance and salience of Environmental treaties, reducing domestic partisan conflicts.

Predictably, both variables measuring the cumulative number of elections and cabinets have a negative and significant impact on treaty ratification. An increase in the number of cumulative elections and cabinets corresponds to a decrease in the likelihood of ratification or, in other words, to longer ratification processes. Unsurprisingly, the treaty ratification process was faster in the last legislature. Importantly, this variable does not have a substantial confounding effect on the relationship between ideology and ratification likelihood. This can be interpreted as evidence that M5S's rise to power did not significantly alter the politics of treaty ratification in Italy.

Conclusions

In this article, we presented an original dataset containing a large number of significant treaties signed and ratified in Italy and then looked at the determinants of the duration of the ratification process. Treaty type and issue area are important factors in understanding treaty ratification dynamics in Italy. On the one hand, multilateral treaties involving Italy and other states take, on average, significantly longer to ratify than bilateral treaties. On the other hand, treaties dealing with issues entailing significant implementation costs, such as the environment, are subject to longer ratifications. Shifts in government ideology also seem to determine the duration of the ratification process: the more cabinets’ ideology moves to the left, the shorter the duration. This left–right gap is reduced for multilateral, environmental and security treaties.

Through such findings, this article contributes to the understanding of patterns and tendencies in state commitment to international treaties in three ways. First, it shows the importance of the number of actors involved in a treaty, not only its issue area. In fact, this characteristic of the treaty has fundamental implications on how states behave and expect fellow states to behave. Following a liberal institutionalist logic (Keohane 2005), the higher the number of states involved, the higher the level of uncertainty about commitment and compliance, ceteris paribus. Our empirics on Italy definitely support such an argument: bilateral state-to-state treaties stimulated a much shorter ratification process. In particular, such treaties tend to merely lay down in written form precise commitments already made by Italy and the other party, i.e. the Treaty of Friendship with Libya. Such an element, together with the limited number of actors involved, increases the level of uncertainty.

On the contrary, multilateral agreements may set ambitious goals to be attained by the global community. Not being fully informed about the level of commitment of other parties, Italy also takes its time to ratify such treaties. International organisations may help to solve the collective action problem. In fact, treaties involving institutions stimulated a faster ratification process in Italy. For example, in the case of European Union agreements with non-member state countries, the level of uncertainty about ratification of the agreement in fellow member states is reduced through incentives. Overall, our findings provide evidence for a rationalist approach to state commitment to treaties based on uncertainty about behaviour and institutions.

Second, we highlight the relevance of cabinets’ ideology and its cross-time changes in explaining treaty ratification processes. Various studies highlight fundamental differences between the left and right in foreign policy (Palmer et al. 2004; Ostermann and Wagner 2022; Thérien and Nöel 2000). However, only in a few cases partisanship and ideology have been used as independent variables to explain treaty commitment. We showed that cabinet ideology, as measured on the left–right axis and its shifts, significantly impacts the treaty ratification process in Italy. We also highlighted how such effect has stood the test of time and profoundly changed the party system competition. In fact, the Five Star Movement rise to power after the 2018 elections did not seem to impact the treaty politics in Italy. Therefore, in line with Coticchia (2021), we cast some doubt on a so-called sovereignist revolution in Italian foreign policy. Through such findings, we contribute to the emerging research on the relationship between populism and foreign policy (Destradi et al. 2021). However, further comparative and single-case studies should deepen the research on the impact of cabinet ideology on the treaty ratification process to better understand the role of the left–right cleavage in foreign policy and populist parties' impact on international cooperation.

Third, we examine the ratification process in a middle power like Italy. In this respect, Italy fits within the definition of middle power, i.e. a democratic and egalitarian regime, at the core of the global economy, with a particular status within the international system, depending on whether bipolar or multipolar (Holbraad 1971; Jordaan 2003). Against this background, international cooperation through multilateral and bilateral agreements is fundamental for middle powers to improve their status. That makes them an interesting case to be analysed as great powers such as the USA, if not more. In fact, focusing on a middle power arguably provides more generalisable findings, fitting a larger number of countries with similar constraints and incentives for international cooperation (Coticchia 2021).

In addition, this article engages with the longstanding debate on continuity and change in Italian foreign policy across different cabinets. We deal with such controversy from an innovative perspective, dealing with treaty ratification as foreign policy outputs. The results can be interpreted in two ways. First, it seems that left-wing governments are generally more committed to foreign policy. This result resonates with the idea that right-wing governments are generally more focused on domestic politics. Second, left-wing and right-wing parties in Italy do not have substantially different views concerning commitment to multilateralism. This finding contradicts the argument about a divide between a “multilateralist left” and a “bilateralist right” with regard to Italian foreign policy (Andreatta 2008; Carbone 2007). In other words, we provide evidence that continuity prevailed over change in Italian foreign policy, despite the alternation between centre-left and centre-right coalitions and, later on, the rise of populist parties. In this sense, future research should further test this argument against different Italy’s foreign policy outputs, including bilateral investment and foreign aid.