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Abstract

International law enforcement is an understudied but indispensable factor for maintaining the international order. We study the effectiveness of elite justifications in building coalitions supporting the enforcement of violations of the law against territorial seizures. Using survey experiments fielded in the USA and Australia, we find that the effectiveness of two common justifications for enforcement—the illegality of a country’s actions, and the consequences of those actions for international order—increase support for enforcement and do so independently of two key public values: ideology and interpersonal norm enforcement. These results imply elites can build a broad coalition of support by using multiple justifications. Our results, however, highlight the tepidness of public support, suggesting limits to elite rhetoric. This study contributes to the scholarship on international law by showing how the public, typically considered a mechanism for generating compliance within states, can impede or facilitate third-party enforcement of the law between states.

Keywords

International law public opinion territorial disputes enforcement

Introduction

International law prohibits the seizure of another state’s territory, and scholars consider the decline of territorial conquest as stabilizing for the international system. Yet violations of the law still occur: the post-Cold War period has witnessed at least 15 attempts by states to wrest territory from another state (Altman, 2020).

In an anarchic system, third-party law enforcement offers one potential solution to the problems that law violations pose. The post-Cold War conquest attempts provoked a range of responses: condemnation, economic sanctions, military action. Although international law enforcement is not an everyday phenomenon in international relations, episodes of enforcement such as the Gulf War demonstrate that its consequences are important and sometimes far-reaching. Because enforcement can be costly for a would-be enforcer, whether and how third parties punish violators and reverse violations depend in part on a leader’s ability to build public support.

What explains public support for international law enforcement and how do elite frames of law violations shape the public’s willingness to enforce? Elite justifications for action are important because they describe, interpret, and frame foreign policy issues in the security domain (Chong and Druckman, 2007; Guisinger and Saunders, 2017). International organizations also provide information to the public (Chapman, 2012; Voeten, 2005). However, frames are more effective when they resonate with the public’s values—to the extent that leaders succeed in appealing to public values, public support for action should be stronger (Kertzer et al., 2014; Kreps and Maxey, 2018; Rathbun et al., 2016; Stein, 2015). To be clear, we do not investigate why leaders choose to put some foreign policy issues, such as violations of international law, on the public’s radar. Rather, we explore how leaders sell their decision to respond to a violation once they have elevated the issue. The scope of our project is therefore limited to justifications after a violation of international law. These infrequent opportunities for enforcement make justifications especially important influences on public support.

We study the effects of two common types of justifications in the context of a violation of international law: the likelihood of the breakdown of international order in the absence of enforcement (a consequentialist framing), and the illegality of the violating country’s actions (a legal framing). We examine how the effectiveness of these justifications varies by public values, focusing on ideology (a proxy for moral foundations) and interpersonal norm enforcement (defined as valuing the enforcement of social norms). Put differently, this article studies the kinds of justifications that matter for international law enforcement and the types of individuals for whom these justifications matter.

We examine the effectiveness of these justifications using the case of the law against the violent seizure of territory. Whereas many studies of public influence on coercive international behavior focus on the USA (see, for example, Hildebrandt et al., 2013; Kreps and Maxey, 2018; Rathbun et al., 2016; Tomz, 2007; Wallace, 2013), we innovate by examining two powerful potential enforcer states: the USA and Australia. We draw on public opinion data from these states because they are democracies that are plausible law enforcers and are unlikely to benefit directly from enforcement action. This is because although both the USA and Australia benefit indirectly from the stability and predictability that the territorial order provides, neither is under threat of direct territorial conquest given their geographic isolation.

This project contributes to the growing study of international law and public opinion. A significant body of literature examines the effectiveness of international law from the perspectives of compliance and dispute resolution (Hafner-Burton and Tsutsui, 2007; Owsiak, 2011; Prorok and Appel, 2014; Valentino et al., 2006; Von Stein, 2005). Much of the scholarship on compliance focuses on domestic institutions and the domestic public as mechanisms that facilitate compliance within states (Brutger and Strezhnev, 2018; Chaudoin, 2016; Conrad and Ritter, 2013; Dai, 2005; Lutz and Sikkink, 2000; Simmons, 2009; Wallace, 2013). We shift attention to the problem of third-party enforcement, an important but potentially costly solution to compliance failures. While we share the literature’s view that domestic politics is an important mechanism that influences a state’s decision to comply with international law, we diverge from the scholarship by treating the public as a potential barrier to law enforcement that occurs between states.

Justifications and values

We study public responses to justifications for law enforcement. In the security realm, these justifications come from elites such as leaders and policy experts who play an important role in framing and shaping the public’s views (Chong and Druckman, 2007; Stein, 2015). Because publics are unlikely to be well-versed in international affairs, they rely on elites to provide information and contextualize foreign events. Leaders’ informational advantages underpin their ability to justify robust responses to violations of international law.

We investigate two common justifications that draw on different rationales for action (see Kreps and Maxey, 2018; Maxey, 2020; Zvobgo, 2019). Consequentialist justifications for enforcement are slippery slope arguments that stoke fears about the negative consequences of foreign policy inaction. In the case of territorial seizure, these justifications emphasize the potential breakdown of international order. For example, George HW Bush referenced the logic of breakdown when announcing Operation Desert Storm: “The troops know why they’re there . . . We should all sit up and listen to Jackie Jones, an Army lieutenant, when she says, ‘If we let him get away with this, who knows what’s going to be next?’” (Bush, 1991).

Legal arguments invoke the primacy of international law. Framing an action as illegal reduces ambiguity about the action as a transgression and in turn allows leaders to characterize enforcement as a necessary response (McAdams, 2015; Sandholtz, 2007; Wallace, 2013). Following Russia’s annexation of Crimea, President Obama appealed to law as a justification for sanctions:

Our enduring strength is also reflected in our respect for . . . international law and the means to enforce those laws. But we also know that those rules are not self-executing. They depend on people and nations of good will continually affirming them. (The Washington Post, 2014; emphasis ours)

Whether these justifications resonate with the public likely depends on individual values (Herrmann et al., 1999). Following scholars who have drawn on insights from psychology and behavioral economics to explain foreign policy attitudes, we focus on two types of values. One is ideology, which proxies for moral foundations and personality traits. A large literature has shown that conservatives tend to weight authority (concerns about order) and purity (concerns about contagion) more strongly than liberals, and that ideology influences attitudes toward international law (Gerber et al., 2011; Graham et al., 2011; Haidt et al., 2009; Wallace, 2013). Additionally, conservatives are more likely to view military force as an important tool of international engagement (Kertzer et al., 2014; Wittkopf, 1990). We expect conservatives to be more willing to enforce, particularly when cued about the breakdown of order.

We also examine whether the value one attaches to social norm enforcement induces variation in support for international enforcement. Defending or challenging the social order is not a phenomenon isolated to the international political arena, and some individuals enforce social norms even when it is costly to do so (Balafoutas and Nikiforakis, 2012; Fehr and Fischbacher, 2004). Scholars have suggested that enforcement is a metanorm (Axelrod, 1986). This tendency toward “interpersonal” enforcement should increase support for international enforcement. We also expect that individuals predisposed toward enforcement will be less responsive to elite justifications.

Table 1 summarizes our theoretical predictions.

Table 1.

Hypotheses.

Hypothesis #	Expectation
Hypothesis 1	Cues about the breakdown of order will increase support for enforcement.
Hypothesis 2	Cues about the illegality of a country’s behavior will increase support for international law enforcement.
Hypothesis 3	Conservatives will be more supportive than liberals of enforcing the anti-conquest law.
Hypothesis 4	Conservatives will be more supportive than liberals of using force to enforce the anti-conquest law.
Hypothesis 5	Individuals who are willing to enforce interpersonal norms will be more willing to support enforcement.
Hypothesis 6	Liberals will be more willing to support enforcement when cued about international law, while conservatives will be more willing to support enforcement when cued about the breakdown of order.
Hypothesis 7	Interpersonal norm enforcers will be less responsive to cues than non-interpersonal norm enforcers.

Experimental design

Our research design uses the specific case of the law against conquest to investigate the effect of elite justifications and public values on public support for international law enforcement. The anti-conquest law prohibits the violent acquisition of territory and violent alteration of borders (Fazal, 2007; Zacher, 2001). Although territorial sovereignty is a cornerstone of the Westphalian international system, the law against seizing territory is a relatively recent development, one that arose in response to concerns about major wars being fought over territory.

Because both territorial seizures and enforcement actions are rare, a survey experiment is an appropriate approach for assessing the effect of justifications on the public. We fielded surveys with embedded experiments to large, national samples of adults from two countries that could plausibly engage in international enforcement: the USA and Australia (see Online Appendix for details). Samples of around 2,000 adults were recruited online in each country in April 2016 using the survey firm Survey Sampling International.

The questions used in this study appear in the Online Appendix, and we highlight the critical elements of the survey design and experiments here. The survey presented respondents with a scenario that their country could face in the future. One bullet described a country’s (“Country A”) use of its military to seize territory from another country (“Country B”). To increase ecological validity, the country pair described in the vignette was randomly drawn from a set of four pairs taken from the universe of settled and ongoing territorial disputes (Huth and Allee, 2002). We control for the country pair in all of our models. A second bullet told all respondents that the invading country has a military that is much weaker than the respondent’s country’s military. This second bullet attempts to control for the immediate costs of the enforcement action by presenting a much weaker target than the respondent’s own country. Again, all respondents received these two bullets.

To test the effect of the consequentialist justification, we randomize whether respondents receive information about the possibility of the breakdown of the territorial order absent enforcement. The treatment reads: “Experts warn that if [respondent’s country] does nothing the risk of major war due to land invasions will increase.” This treatment raises the salience of breakdown and the negative consequences of doing nothing.¹ Respondents in the control condition did not receive this bullet.

To test the effect of the legal justification, we randomize whether respondents are told that the aggressor’s action was illegal according to international law. Respondents in the treatment condition received the following: “The behavior of Country A has violated a fundamental legal principle enshrined in international law.” Respondents in the control condition did not see any information about the illegality of the action.

Our dependent variable is public support for enforcement. We measure support for five different enforcement responses asked directly after the scenario. We first asked respondents to what extent they favored or opposed their government using the military to push out the invaders. We then asked respondents to what extent they favored or opposed specific punishments against the invader’s leader, if any. These punishments were: (a) issuing a statement condemning the invading country’s leader, (b) imposing economic sanctions on the leader, and (c) using the military to remove the country’s leader. Finally, a common enforcement tool is for the enforcer to reduce the amount of foreign aid it sends to the violating country if such a relationship exists. Thus, we gauge whether individuals supported or opposed this tactic as well. For each of the five questions, respondents expressed their support or opposition on a four-point scale ranging from 1 if the respondent said, “oppose strongly” to 4 if the respondent said, “favor strongly.”² We created the Enforcement index by averaging over the five questions.³

We then examine how values correlate with support for enforcement and condition the effects of these elite frames. First, we measure ideology by asking respondents to place themselves on a 10-point left-right ideological scale. For both countries, around half of respondents placed themselves at the midpoint of the scale. We code these respondents as “Moderates.” For respondents below the mid-point, we code them as “Liberals.” and for those above, we code them as “Conservatives.”

Second, we investigate the role of social enforcement values. We created a novel scenario to capture whether an individual is an “enforcer type.” This scenario describes a hypothetical encounter at a busy post office in which they see someone cut in line. Those who say they would confront the line-jumper (about a third of the sample in both countries) are coded as third-party interpersonal norm enforcers.⁴ The full experiment appears in the Online Appendix 2.

Findings

We first discuss general patterns of support for enforcement across our enforcement measures (Table 2). Overall levels of support across both samples are lukewarm, with some heterogeneity across the different types of enforcement policies. Two enforcement responses involve military action; these policies are significantly more costly than the non-militarized responses. As we expected, individuals are more likely to support the relatively less costly non-militarized enforcement actions compared to militarized actions. Virtually costless verbal condemnation received the highest amount of support, but even in this case the mean response was “favor somewhat.” The fact that individuals are more likely to support lower cost enforcement actions is not necessarily surprising, but it does suggest that respondents are reacting in the expected way to our scenario. This relative restraint is consistent with popular depictions of an inward turn in many Western states—and interestingly, predate the Trump presidency in the USA. Because it is not costly to support a policy in an artificial survey setting, support for enforcement in response to a real violation may be even lower.

Table 2.

Patterns of Support for Enforcement.

	USA	USA	Australia	Australia
	Mean	Percent Support	Mean	Percent Support
Condemn in Statement	2.98	73	3.20	82
Economic Sanctions	2.94	73	3.02	78
Reduce Foreign Aid	3.95	76	3.02	75
Remove Leader	2.28	40	2.06	31
Reverse Violation	2.41	47	2.22	37

Note: Each variable ranges from 1 to 4 with higher numbers indicating more support for the enforcement action. To calculate “Percent Support,” we take the percentage of respondents reporting that they “support/favor strongly” or “support/favor somewhat” the enforcement action. The table includes only the mean and percent support for respondents in the control category that did not receive elite justifications. We pool all other treatments.

We now turn to the effects of consequentialist and legal justifications (H1 and H2). We explore these effects by regressing our Enforcement index on binary indicators for the treatment conditions and control variables for the other experimental manipulations (severity of the violation and country pair). The justifications treatment gives us four conditions: a control condition, an illegal condition, a breakdown condition, and a condition in which respondents received both the illegal and breakdown frames.

We find significant support for H1 and H2 in both countries. Figure 1 reports the average treatment effect for each treatment on support for enforcement. Both the Law treatment and the Breakdown treatment significantly increase support for enforcement actions relative to the control.

Figure 1.

Average Treatment Effect of Elite Justifications.

Next, we look at the unconditional effects of individual values. We find significant support for our expectations. Table 3 holds the results of OLS regression models separating the dependent variables into military and non-military enforcement actions, since public opinion is less likely to matter in the latter case.⁵

Table 3.

Individual Correlates of Support for Military and Non-Military Enforcement Actions.

	USA	USA	Australia	Australia
	Military	Non-Military	Military	Non-Military
Ideology	0.02***	0.01*	0.03***	0.01
	(0.01)	(0.01)	(0.01)	(0.01)
Interpersonal	0.19***	0.13***	0.12***	0.12***
	(0.04)	(0.03)	(0.04)	(0.03)
Constant	2.42***	2.10***	2.46***	2.37***
	(0.13)	(0.11)	(0.12)	(0.10)
Observations	1991	1976	1989	1975
R ²	0.14	0.10	0.14	0.10
Controls	Yes	Yes	Yes	Yes

Note: The table reports OLS coefficient estimates. The dependent variables are additive indexes of support for the military and non-military enforcement actions. Each dependent variable ranges from 1 to 5. Interpersonal is a variable coded 1 if the respondent is a self-reported interpersonal norm enforcer and 0 if the respondent does not enforce interpersonal norms or was unsure. Ideology ranges from 1 to 11 with smaller values representing the left and larger variables representing the right of the ideological spectrum. Education categories are tailored to the specific country. All models include the following controls: religiosity, gender, age, having a child, educational attainment, and employment status (see Online Appendix for coefficients). Heteroskedastic-consistent robust standard errors are in parentheses. All results are unweighted. ***p<0.01, **p<0.05, *p<0.1.

In both the USA and the Australia samples, Ideology is significantly and positively associated with support for international law enforcement across both types of actions (H3 and H4). Ideology is coded such that smaller values indicate placement on the liberal side of the scale and higher values indicate placement on the conservative side. Thus, a positive correlation demonstrates that conservatives are more supportive of enforcement than liberals. By breaking the dependent variable into military and non-military actions, we can further show that the correlation between ideology and enforcement is especially strong for military actions, but less so for non-military enforcement. This suggests that the US and Australian publics may be particularly polarized on issues of military intervention but that there may be more bipartisan support for non-military enforcement.

We show that individuals who enforce norms in their everyday lives are more likely to support their government intervening to enforce international law (H5). The coefficients on Interpersonal are strong and positive across both categories of norm enforcement.

Our last analysis examines how ideology and interpersonal norm enforcement condition the effects of elite justifications on support for enforcement. To recap, we argue that liberals are more likely to respond to the legal justification and that conservatives are more likely to respond to the consequentialist justification in this issue area (H6) (Wallace, 2013). We also expect that elite justifications have a smaller effect among interpersonal norm enforcers as these individuals need less persuading than others (H7).

Surprisingly, we find little evidence to support these claims. As shown in the Online Appendix, both the legal and consequentialist justifications continue to have a strong positive effect on support for enforcement across the ideological spectrum (liberal to conservative) and regardless of individuals’ personal tastes for enforcement in the two countries we study. This surprising result suggests that these frames appeal to individuals regardless of their ideology or beliefs about interpersonal enforcement.

Discussion

The contemporary territorial order is facing challenges on numerous fronts. From Russian aggression in Ukraine to Chinese confrontation in the South China Sea, these actions threaten territorial sovereignty and could destabilize the existing rules-based order. With democratic publics skeptical of playing the world’s police officer, leaders that wish to enforce international law will need to frame policy responses to convince the public.

This article points to several places to look for a supportive public. We examine elite justifications and individual values, finding that these factors can induce variation in public support for enforcement. Informing publics that seizing territory is illegal and could result in the breakdown of the territorial status quo increases support. Importantly, neither justification decreases support, and there is little evidence that individuals respond to the justifications differently based on ideology or a propensity toward interpersonal norm enforcement. These findings suggest when the rhetoric that elites use to build public support can be successful. In particular, cues that combine these justifications may build the broadest coalition without eroding support in the political base.

Our article also has potentially sobering implications about the future of third-party enforcement. Our survey results, which predate President Trump’s election, show lukewarm support for most enforcement actions for a fundamental law in the international legal system. This tepidness is striking—even in the artificial, cost-free context of a survey experiment, respondents were reluctant to support enforcement. These results would likely be even weaker in a real-world scenario where the risks are more salient or if the violator were a powerful state—just as the world saw with Russia’s seizure of Crimea.

This article thus joins other recent scholarship in pointing to a backlash to international law among growing segments of the public (Brutger and Strezhnev, 2018; Chaudoin, 2016). If leaders and their justifications are necessary for mobilizing the public to take these strong actions, we should not expect the USA or Australia to take a leading role in enforcing international law in the world or even in their own region. It will therefore fall to other powerful states to take up the mantle of the world’s police officer.

Supplemental Material

randP_replication – Supplemental material for Selling international law enforcement: Elite justifications and public values

Supplemental material, randP_replication for Selling international law enforcement: Elite justifications and public values by Melissa M. Lee and Lauren Prather in Research & Politics

Supplemental Material

selling_production_appendix – Supplemental material for Selling international law enforcement: Elite justifications and public values

Supplemental material, selling_production_appendix for Selling international law enforcement: Elite justifications and public values by Melissa M. Lee and Lauren Prather in Research & Politics

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors received financial support from the University Center for Human Values at Princeton University.

Supplemental materials

The supplemental files are available at

The replication files are available at

Notes

Carnegie Corporation of New York Grant

This publication was made possible (in part) by a grant from the Carnegie Corporation of New York. The statements made and views expressed are solely the responsibility of the author.

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