2. Defining traditional law

Many alternative terms have been used when referring to traditional law. They include informal law, customary law, personal law, and indigenous law. No universally accepted taxonomy has emerged yet. Here, we refer to traditional law as consisting of institutions (1) based on a rule that is not subject to deliberate human design and (2) enforced by actors that are independent from the state. From the point of view of the New Institutional Economics (NIE), the different terms used for traditional law all describe types of institutions. Here, we propose a more systematic terminology that clearly delineates these types of institutions from each other. Institutions can be defined as commonly known rules that structure recurrent interactions and are endowed with a sanctioning mechanism that may be employed in case of non-compliance with said rules (Voigt, Reference Voigt2013). Institutions, hence, are composed of a rule and a sanctioning component. The term ‘law’ refers only to a subset of institutions, as it does not entail self-enforcing rules or rules complied with due to someone's own ethical convictions. If a state exists, sanctions for rule violations can be implemented either by representatives of that state (‘external’ institutions) or by regular members of society (‘internal’ institutions). Within the category of internal institutions, we can distinguish between sanctions carried out in an unorganized, spontaneous way, for example by ignoring or criticizing people who do not conform to some dress code, and those imposed by a private organization, such as a customary court.

Institutions do not only vary in terms of the way sanctions are implemented, but also with respect to the type of rule that is enforced. North (Reference North1990) proposes a well-known distinction between formal and informal rules and, by extension, between formal and informal institutions (see also Hodgson, Reference Hodgson2015).Footnote ² Here, we propose to use an alternative distinction between rules according to the mode by which they are formulated in the first place and then modified over time. We distinguish four modes of creation and modification: (1) rules considered to be designed by some deity, (2) rules emerging from an evolutionary process that is largely exempt from deliberate modification, (3) rules formed in an evolutionary process with ample opportunity for non-state actors to deliberately modify them, and finally (4) rules passed by the government.Footnote ³

North's (Reference North1990) distinction between formal and informal institutions is based on whether a rule is codified (see also Voigt, Reference Voigt2018). In contrast, we focus here on the two categorizations discussed above that are based on: (1) the main actors involved in the design of rules, and (2) the way non-compliance with the rules is sanctioned.Footnote ⁴ Combining these two categorizations of rules and sanctions results in a 3 × 4-matrix depicted in Figure 1. When the state sanctions rule violations even though the rules were not promulgated by state organs, we refer to these institutions as ‘hybrid law.’ We further propose to distinguish between the different kinds of laws that are enforced by members of society, based on who designs the rule component of these laws. Although such a fine-grained taxonomy might be helpful, in the current study we focus largely on the distinction between external, hybrid, and traditional law. We, hence, use ‘traditional law’ as a generic term that comprises religious (or personal) and customary (or indigenous) law.

Figure 1.

Categories of law: creation versus enforcement.

Evidently, religious law does not presuppose that a rule was actually designed by a deity – it suffices, if its design is attributed to one. The resulting distinction between customary and religious law – i.e. reference to the will of a deity versus reference to long established rules of conduct – might be of interest primarily because of its effects on rule compliance and the costs of modifying rules.

It is also noteworthy that the same rule can exist simultaneously in different institutions in our matrix and this is often the case in practice. If, for example, the state chooses to adopt state law that is perfectly congruent with religious or customary law, then the same rule that was previously enforced spontaneously or by private actors is now also enforced by agents of the state. In such cases, economists often refer to the risk of crowding out (see, for example, Rodrik, Reference Rodrik2008: 101). Being aware that there is a matching state law that is enforced by state actors, private actors may be tempted to reduce their enforcement efforts over time, forcing the state to invest even more resources to maintain high levels of compliance. On the other hand, the amount of resources needed to enforce a rule that is already enforced by other actors is lower than if a state law was introduced that is inconsistent with local beliefs and traditions. Finally, rule creation is not meant to refer to who invented a rule in the first place; legal transplants or implemented EU directives, for example, are state law no matter where they were originally conceived.Footnote ⁵

3. Determinants of the use and quality of traditional law

3.2 Reasons for the prevalence of traditional law

3.2.1 The relevance of power

Assuming power-maximizing representatives of the state, the prevalence of traditional law can be interpreted as indicating the limits of their power over those demanding and supplying alternative legal institutions. After all, the existence of traditional law may imply sacrificed tax revenues, but also limits the ability of politicians to implement their most preferred ways of structuring interactions. Compared to a situation in which, ceteris paribus, no traditional law exists, the prevalence of traditional law suggests a lower utility level of politicians.

However, utility maximization (as opposed to power maximization) may motivate politicians not to strive for control over everything, as the marginal costs of more control might outweigh the gains. Colonizers, as well as others striving to cling to power in a country, may consider the way in which some interactions are structured not to be vital for their political goals.Footnote ⁷ Since more control in such cases has the potential of producing only small benefits while causing significant (economic or political) costs, politicians might rationally refrain from implementing their most preferred law.

Cost-benefit considerations also play a dominant role when local leaders are influential and eliminating or replacing their justice system would be costly for the central government. These costs arise because once traditional law exists, local elites have a strong interest in keeping it in place, if it generates sufficiently large rents for them (see, e.g. Sarch, Reference Sarch2001). It has even been argued that under colonial rule, many ‘traditions’ were genuinely invented on the local level because that was a promising way to refuse compliance with legislation newly established by the respective colonial power (Barnes, Reference Barnes1951; Hobsbawm and Ranger, Reference Hobsbawm and Ranger1983). Such exemptions were based on the fear that if compliance with newly passed legislation implied committing sacrilege, potential costs for the central government could be substantial. Colson (Reference Colson1974: 80) summarizes the argument succinctly: ‘Men had to cite precedent to justify their demands and necessarily, therefore, they invented precedent.’

Acemoglu and Robinson (Reference Acemoglu and Robinson2012: 242f.) refer to the Sudan as an example for a lack of centralization due to local political interests: ‘To politically centralize would have meant that some clans would have been subject to the control of others. But they rejected any such dominance, and the surrender of their power that this would have entailed.’Footnote ⁸ The continued existence of traditional law, hence, could indicate that local leaders are, compared to the central government, relatively powerful.

Until now, the argument has been focused on the interests of the political elites, be they colonizers, national politicians or local leaders. Yet, the function of institutions is to structure recurrent interactions between many actors far beyond the elites. Those actors constitute the demand side for traditional law, and are an important factor in explaining the prevalence of traditional law. Acemoglu et al. (Reference Acemoglu, Cheema, Khwaja and Robinson2020), for example, show that informal, traditional adjudication might be used largely because the formal judiciary of the state is perceived to be ineffective by citizens.

We now propose to look at three types of situations in which the likelihood that traditional law prevails is a function of the power the central government enjoys, both vis-à-vis local leaders as well as the citizens at large. All three situations show the potential relevance of traditional law as a set of second-best institutions in a second-best world (Rodrik, Reference Rodrik2008).

The first situation is one without a state. This implies the absence of any power of a central government over local leaders. If there is no state to enforce property rights, huge gains from trade could remain unrealized (North et al., Reference North, Wallis and Weingast2009: 18 call this the natural state). To be able to reap at least some of those potential gains, private parties will create organizations and institutions that help enforce contracts. Greif (Reference Greif1989), for example, shows how the Maghribi traders managed to deal with principal-agent problems in long distance trade by forming coalitions. Membership in these coalitions was highly exclusive and members had to comply with a number of rules (such as never to employ an agent who had previously cheated another coalition member). Milgrom et al. (Reference Milgrom, North and Weingast1990) offer empirical evidence of medieval institutions that were developed and used by merchants.

Second, a state might exist, but offers institutions that are not in line with the needs of private law subjects. In this case, the prevalence of traditional law is a consequence of state-enforced law not reflecting the interests of its private users. If the state and its government are very powerful, they can force the private law subjects to draw on external institutions, even if they are not designed to the liking of private law subjects. Logan (Reference Logan2013), for example, argues that traditional law survives because it enjoys legitimacy and not because the state is particularly weak.Footnote ⁹ Oto-Peralías and Romero-Ávila (Reference Oto-Peralías and Romero-Ávila2014) claim that chiefs in some African countries misused their position after the onset of colonization, which lowered their legitimacy, and reduced the probability that traditional law continues to play an important role in these countries.

In a third situation, a state might exist and its legislation might even be in line with the preferences of citizens, but reliance on external institutions might be too costly for potential users due to the monetary costs of using the law, the length of court proceedings, uncertainty about the interpretation of rules, judicial corruption, and so on. After the Genocide in Rwanda, for example, a modified traditional court system was introduced that increased access to justice services and reduced the backlog of the formal justice system (O'Reilly and Zhang, Reference O'Reilly and Zhang2018). As in the previous situation, if the state and its government are very powerful, private law subjects can be forced to draw on external institutions even if they are costly to use.

These three scenarios are based on power. The more powerful the public authorities are relative to the citizens, local leaders, etc., the less relevant traditional law becomes, even if traditional law would be preferred by its potential users. In sum, almost all our arguments are based on power relationships. They refer to the relative power of center and periphery, but also the relationship between politicians and citizens. Power, however, is difficult to ascertain empirically. Thus, the question is whether a number of empirically testable statements can be derived.

3.2.2 Hypotheses

We propose to arrange our hypotheses according to a simple criterion, namely the degree of exogeneity of the explanatory variable. We begin with the most exogenous factor, which is geography, followed by prevalent family structures and the antiquity of the state, before we end with colonial history. Our hypotheses and their relationship to the theoretical arguments presented in the previous subsection are summarized in Figure 2. As can be seen, the factors we are interested in are expected to exert their influence on the relevance of traditional law in modern-day societies either via the likelihood that state-created rules are unattractive for the citizens or via the likelihood that state-enforcement of rules is ineffective.

Figure 2.

Determinants of the relevance of traditional law.

We now move on to present four hypotheses:

H1: More stable climatic conditions favor a higher relevance of traditional law in modern societies.

We hypothesize that one group of factors determining the ubiquity of traditional law are the prevalent geographic and climatic conditions. Giuliano and Nunn (Reference Giuliano and Nunn2017) hypothesize that the adequacy of a people's customs is a function of the stability of the environment: If the environment is stable, the current generation can profit most from knowledge of previous generations. If, however, the environment is volatile, e.g. with respect to climatic conditions, customs will tend to be less appropriate for the current needs of the population. Giuliano and Nunn show that peoples that were subject to an unstable environment, in terms of variation of temperature over the period from 500 to 1900 A.D., attribute less importance to customs and norms today. These differences in values could function as a causal mechanism linking climatic instability to reliance on traditional law.Footnote ¹⁰

H2: The larger the share of endogamous marriages, the higher the relevance of traditional law in modern societies.

Norms supporting both the establishment and maintenance of a state might also be important for the development of an efficient formal legal order. Todd (Reference Todd1985), among others, argues that a society's political organization mirrors its family structures. Moreover, family structures are assumed to be highly stable over time. Todd argues that a specific form of endogamy, namely consanguinity, i.e. the practice of cousin marriage, can pose ‘an insurmountable obstacle to the construction of the state’ (Todd, Reference Todd1985: 144), as the depersonalization of power is supposedly inimical to endogamous family types.Footnote ¹¹ Endogamy would then be linked to traditional law via the emergence of less effective state institutions. Schulz (Reference Schulz2019) can indeed demonstrate that consanguinity is causally related to less civicness and less inclusive political institutions in modern-day countries (see also Schulz et al., Reference Schulz, Bahrami-Rad, Beauchamp and Henrich2019).

H3: Higher state antiquity is linked to a lower relevance of traditional law in modern societies.

The conjecture about the relevance of early state development is straightforward and in line with the thinking of Max Weber, as sketched above: The longer a state-like structure has been in existence, the more likely it is that politicians will have established a powerful centralized legal system that does not rely on traditional law. Arguments outlining the advantages of an early state have been put forward by Bockstette et al. (Reference Bockstette, Chanda and Putterman2002), and more recently by Borcan et al. (Reference Borcan, Olsson and Putterman2018). One causal mechanism linking state antiquity to the contemporaneous prevalence of traditional law would be the earlier development of an effective legal system under the control of the state. Gennaioli and Rainer (Reference Gennaioli and Rainer2007) find that precolonial centralization predicts the quality of contemporaneous public good provision, implying that having been under the influence of colonizers might not be the most relevant explanation for differences in the provision of public goods today (see also Maseland, Reference Maseland2018).

H4: The higher the share of citizens of European descent, the lower the relevance of traditional law in modern societies.

Acemoglu et al. (Reference Acemoglu, Johnson and Robinson2001) argue that colonies characterized by an inhospitable environment made the creation of a powerful state with efficient and inclusive institutions less attractive. Based on this argument, the legitimacy of the established central government (relative to more traditional forms of authority) differed depending on whether the colony was treated with inclusive or extractive institutions. Easterly and Levine (Reference Easterly and Levine2016), in contrast, argue that any adverse effects of extractive institutions established by colonizers should have been more than offset by the human capital and technology brought by Europeans, even in small settlements without inclusive institutions. Gutmann and Voigt (Reference Gutmann and Voigt2018a) show that the share of European descendants among the population is indeed a powerful predictor of high-quality legal institutions. This observation is consistent with the idea that European populations reduced the need for traditional law because they increased societies' levels of human capital and technology and thereby made it possible to sustain high-quality legal institutions set up by the state. Seidler (Reference Seidler2014), for example, demonstrates the need for educated bureaucrats and general education to transplant external institutions effectively.

4. Data and bivariate correlations

Data on traditional law that is available for and comparable across a large number of countries is scarce. Here, we rely on three sources: the Institutional Profiles Database (Bertho, Reference Bertho2013), the World Justice Project (Botero and Ponce, Reference Botero and Ponce2011), and a report by the World Bank (2018).

The World Bank has published its report ‘Women, Business and the Law’ biannually since 2010. We use four de jure variables contained in that report to depict the formal recognition of traditional law. The report proposes a distinction between customary law and personal law. According to the report, ‘personal law refers to non-customary legal systems that stem from tradition or doctrinal texts, which are sometimes uncodified’ (World Bank, 2018: 27). It includes law derived from religious belief, governing areas such as personal status, crime, and commerce. Since religious roots seem of overwhelming importance for this category, we refer to it here as religious law. The legal status of social norms can have important consequences for public policy. Gouda and Gutmann (Reference Gouda and Gutmann2019), for example, show that Muslim countries only display increased levels of minority discrimination if their constitutions formally recognize Islamic law.

The four indicators measure the answers to the following questions: ‘Is customary [/personal] law recognized as a valid source of law under the constitution?’,Footnote ¹² and ‘Does the law recognize customary [/personal law] courts that adjudicate exclusively on customary law [/personal law]?’Footnote ¹³ Positive responses are coded as 1 and negative responses are given a 0.

From CEPII's Institutional Profiles Database, we use one de facto variable that indicates the share of rural land administered under traditional law (including its use: grazing, transhumance, exploitation, etc.) measured on a scale from 0 (no land under a traditional rights system) to 4 (very large parts under traditional rights systems). At the moment, this is the only available indicator of the extent to which traditional law is relied upon in practice to structure interactions. Unfortunately, it only covers one very specific area of application, namely the governance of rural land (land rights). However, land rights are of particularly high importance in economies relying on agriculture. In addition, Colson (Reference Colson1974: 82) observes that appeals to tradition to legitimize behavior fail when people live in circumstances that they have not lived in traditionally. She concludes that people living in urban centers or employed by industry have fewer tools for defending themselves against government officials who try to impose state law on them. This observation would suggest that putting land rights center stage is well justified.Footnote ¹⁴ Another argument for focusing on the use of traditional land rights is that they are more easily quantifiable and comparable across countries than other rights. The share of area governed by traditional law is easily observable, whereas the number of criminal law or family law cases decided according to traditional law is not only very difficult to inquire, but it might also be more difficult to compare across countries at different stages of economic development and with a different social organization.

The World Justice Project provides more de facto indicators to measure the way in which traditional law is applied. The report asks to what degree the behavior of traditional rulers and that of religious judges is perceived as ‘impartial and fair.’ As impartiality is an important trait of the rule of law, this variable can serve as an important piece of information regarding the (perceived) compatibility between traditional law and the rule of law (impartial).

The WJP further reports to what extent the people surveyed agree with the statement that chiefs or traditional rulers respect the fundamental rights of all people and whether people could refuse to be judged by those rulers. Since it has been argued that a minimal protection of fundamental rights is an important component of the rule of law, the answers to these questions shed additional light on the compatibility between traditional law and the rule of law (basic rights).

Consider the case in which the state-enforced law of a country is compatible with the rule of law, while its traditional law is not. As long as it is possible to opt out of using traditional law without any negative consequences, the negative effects for individuals are clearly limited. One question the WJP asks is to what degree people believe they can opt out of the traditional law system. Although the question does not explicitly mention potential costs of opting out, the answers convey a sense of whether people believe that they effectively have a choice.

The rule of law is not only concerned with the content of the law, but also with the difficulty of getting court decisions, and getting them enforced. The WJP contains three questions that fall into this category. It asks how long it takes to obtain a judgment from a traditional ruler. It asks further, how long it takes to get an award enforced, and finally it enquires into the relative costs of appealing to traditional rulers. Together, these indicators measure whether the traditional law system offers timely and effective adjudication in practice (timely).

Table 1 below shows the correlation matrix of the variables just described. It shows that the share of rural land administered under traditional law is uncorrelated with both the quality indicators from the WJP, as well as the indicators regarding formal recognition of traditional law from the World Bank.

Table 1.

Correlation matrix of traditional law indicators

Note: *p < 0.05, **p < 0.01, ***p < 0.001.

The extent to which traditional law is used in the governance of rural land [5] is positively correlated with the formal recognition of customary law [1]. This suggests that the formal recognition of traditional law can be expected to have measurable consequences in practice. Looking at the bivariate correlations among the three quality indicators by the WJP, it turns out that only the correlation between impartiality [7] and the respect for fundamental rights [8] is statistically significant. As there is no logical connection between the timeliness of traditional law [6] and either its impartiality or the respect for fundamental rights, the low correlations between these variables appear plausible. The timeliness and effectiveness of traditional law seems to be better where it is made use of more extensively (in land governance). Causality could run in both directions in this relationship. The correlation of the three de facto quality indicators by the WJP with the de jure indicators by the World Bank [1–4] is low, indicating that formally recognizing and enforcing traditional law may not lead to its improvement, and vice versa. Finally, the correlations among the four de jure indicators accord well with our intuition: If traditional law is recognized by the constitution [1/3], the likelihood is high that courts enforce it [2/4]. Interestingly, the formal recognition of customary law is not significantly correlated with the formal recognition of religious law and the presence of customary courts is unrelated to the presence of religious courts. These observations provide empirical support for the conceptual distinction we propose between religious and customary law as two separable types of traditional law. Overall, the proxies for the extent of reliance on traditional law, its quality, as well as its legal status are significantly correlated with each other only in select cases. Distinguishing the different concepts, thus, seems important.

We now move on to describe the bivariate correlations between the variables representing traditional law and some potential correlates of the contemporaneous relevance of traditional law. Table 2 depicts the correlations with income per capita, population size, the level of democracy, as well as the rule of law level.Footnote ¹⁵ Polity2 serves as the indicator of democracy and the other indicators come from the World Bank's Worldwide Governance Indicators and its World Development Indicators. The extent to which traditional law is used in the governance of rural land is negatively correlated with contemporaneous measures of income, democracy, and the rule of law. Rich countries whose governments abide by the rule of law do not rely on traditional law to structure transactions.

Table 2.

Correlation between traditional law and its proximate determinants

Note: Pearson correlation coefficients, *p < 0.05, **p < 0.01, ***p < 0.001.

Interestingly, the proxy indicator for the effectiveness and timeliness of traditional law is also negatively correlated with income and the rule of law. Quite simply, rich and rule of law-abiding countries do not rely on traditional law. Traditional law, hence, is not well developed in these countries, which would explain the negative correlations with its timeliness. In line with our intuition, respect for fundamental rights is positively related to income, the level of democracy, and the rule of law. The de jure status of customary law is negatively related to both income and the rule of law, whereas the de jure status of religious law is negatively correlated with democracy.

Table 3 shows correlations between the traditional law indicators and historical as well as geographical variables. Societies that prefer, rather than just permit cousin marriage, coded according to the instructions by Rijpma and Carmichael (Reference Rijpma and Carmichael2016) and using data by Giuliano and Nunn (Reference Giuliano and Nunn2018), are more likely to recognize religious law, which is consistent with our second hypothesis. However, this result might be driven by Muslim countries, which are known for practicing endogamy. We find a strong positive correlation between the Islamic State Index (ISI) by Gutmann and Voigt (Reference Gutmann and Voigt2015) and the formal recognition of religious law.Footnote ¹⁶ Traditional law also seems to be implemented more and at a higher quality in endogamous societies, both in terms of its speed and its impartiality.

Table 3.

Correlation between traditional law and its fundamental determinants

Note: Pearson correlation coefficients, *p < 0.05, **p < 0.01, ***p < 0.001.

We use data by Bockstette et al. (Reference Bockstette, Chanda and Putterman2002), which has been ancestry adjusted by Putterman and Weil (Reference Putterman and Weil2010) to measure if a society's population originates from an area with early state development. If the ancestors of a country's population experienced early statehood, this country is less likely to formally recognize customary law today, which is consistent with our third hypothesis. However, religious law is more likely to be recognized in these countries and the quality and use of traditional law is not different from other countries.

In line with our fourth hypothesis, the presence of a higher share of European descendants in the population, as measured by Putterman and Weil (Reference Putterman and Weil2010), is negatively associated with most of our traditional law indicators. European influence makes the formal recognition of traditional law, as well as land governance under traditional law, less likely. Although traditional law is less timely and effective in these countries (probably due to its limited use), it is not less impartial and even more compatible with fundamental rights.

5. Estimation approach and results

In this section, we report results from regression analysis. The choice of variables is motivated by the theoretical conjectures derived in Section 3, but also by the availability of data. Unfortunately, we cannot test our first hypothesis at this point, as estimates for the historical stability of climate are not yet publicly available.

The factors determining the degree to which traditional law is recognized by the state-supplied legal order are depicted in Table 4. For simplicity, we estimate linear probability models. State antiquity is significantly correlated with both customary and religious law. Interestingly, however, its role is ambivalent: the older a given state, the less likely it is to formally recognize customary law, whereas it is more likely to formally recognize religious law. This might indicate that the state is more likely to crowd out customary law over time in places where it is still prevalent today. Religious law, however, can be used by the state as a source of legitimacy and is, thus, more likely to prevail. This political economy explanation might be part of the reason why proponents of Max Weber's secularization hypothesis find it hard to empirically validate its predictions.

Table 4.

Legal status (de jure)

Note: OLS coefficient estimates with robust standard errors in parentheses, *p < 0.05, **p < 0.01, ***p < 0.001.

As observed before, a higher share of European descendants is correlated with a lower probability of both customary and religious law being formally recognized. When the political and societal importance of Islam in a country is taken into account, the permissibility of cousin marriage is no longer linked to the formal recognition of religious law. Islam itself is associated with a higher likelihood that religious law is formally recognized.

In Table 5, we explain the extent of the use of traditional law based on the specific case of the land tenure system. Early state development is not related to the use of traditional law in rural land governance and neither is the permissibility of endogamous marriages. The finding that a higher share of European descendants is correlated with less reliance on traditional law is not surprising at all. In contrast, a political system in which Islam plays an important role shows significantly more use of traditional law institutions.

Table 5.

Use and quality (de facto)

Note: OLS coefficient estimates with robust standard errors in parentheses, *p < 0.05, **p < 0.01, ***p < 0.001.

Table 5 also explains variation in the three quality-indicators from the WJP. In spite of the limited size of the WJP dataset, these regressions are based on at least 80 observations. Out of our four potential explanatory variables, only the share of European descendants is correlated with timeliness at conventional significance levels; the higher their population share, the less timely the adjudication of traditional law courts. We try to make sense of this finding by pointing at the fact that in countries with higher shares of European descendants, traditional law courts only play a marginal role to begin with, undermining their ability to utilize (dynamic) economies of scale.

Whereas our hypothesis that countries permitting endogamous marriage are more likely to legally recognize traditional law (or courts) cannot be confirmed, the relationship between countries allowing endogamous marriage and the perceived quality of traditional law courts accords well with our intuition. If traditional law courts are used in these countries (no matter whether they enjoy official recognition or not), they are perceived as impartial and fair. This can be interpreted as the flipside of the general skepticism vis-à-vis an anonymous state.

We perform a number of checks of the robustness of our results. First, we replace the indicator for cousin marriage by Rijpma and Carmichael (Reference Rijpma and Carmichael2016) with the one suggested by Giuliano and Nunn (Reference Giuliano and Nunn2017), which is calculated based on data from Giuliano and Nunn (Reference Giuliano and Nunn2018). The results are virtually identical, although the two indicators are only correlated at 0.67. Next, we control in all regression models for the ruggedness of the terrain in a country, measured by Nunn and Puga (Reference Nunn and Puga2012). Ruggedness could have affected the timing of state formation and it could also be relevant to the contemporary preference among the population for having a centralized homogenous state law. We do not find that ruggedness is a relevant confounding factor. Controlling for it does not change our results and ruggedness itself shows no statistically significant effect in any of the regression models. Alternatively, we control for a country's level of ethnic fractionalization. The rationale behind this control variable is analogous to the case of ruggedness. Also here, we do not find that any of our results are sensitive to including this control variable. Ethnic fractionalization itself only exhibits one noteworthy result. More ethnically fractionalized societies make more use of traditional law.