Elections are central to representative democracies, and the systems used in their conduct are crucial because they can profoundly influence political outcomes. Electoral rules have effects on political party systems (e.g., number of parties and level of polarization) and may also help to ease or exacerbate conflict. Furthermore, they help shape the behavior and incentive structures of political actors. They may even influence what use politicians might make of public resources to build linkages with their constituencies.

Thus, particularly relevant in the Latin American region are the presidential electoral rules, the focus of Cynthia McClintock’s book. This book offers a detailed analysis of the two dominant models: plurality (first past the post, even if not receiving a majority of the votes) and runoff (second round of votes between the two leading candidates of the first round). There are arguments to support (or reject) both. But a very interesting point emerges from who supports what. While a vast majority of political leaders support runoff, as shown by the PELA survey and the author’s interviews with Latin American MPs, scholars tend to be skeptical and more inclined to support plurality.

The typical argument is that plurality inhibits the proliferation of political parties and concomitantly decreases the risk of outsiders, as well as executive-legislative blockages (favoring legislative majorities), which can provoke democratic breakdown. On the other hand, runoff, McClintock argues, “opens the political arena to newcomers; it lowers barriers to entry into effective competition in the presidential election. But, at the same time, it assures that (a) the president has majority suport and, accordingly, legitimacy and (b) the president is not at an ideological extreme” (3).

The military coup that overthrew the Chilean leftist president Salvador Allende in 1973 is commonly used as an example of the negative consequences of plurality. Allende was elected in 1970 with 36.6 percent of the vote, while the rightist candidate tallied 35.3 percent and the candidate of the center 28.1 percent. The “birth defect” of Allende’s government would be election through plurality (first past the post). However, McClintock notes a surprising fact in her introduction: the Chilean Constitution provided that if no candidate reached a majority, the president would be chosen between the two most voted candidates; but the tradition was that the candidate with the most votes would be approved. Interestingly for the whole proposal, it was not the lack of a good rule but the lack of application that would explain the 1970 government’s “birth defect” (ceteris paribus alternative explanations of what happened there).

Beyond the Chilean case, a growing institutional diffusion of runoff can be observed in the past few decades. Looking at the whole region, if before 1970 runoff was in place only in Costa Rica, by 2016 runoff was in use by 12 of the 18 Latin American countries that held elections. This offers the required evidence to assess the implications of runoff versus plurality rules, with the main goal of identifying the effect of presidential election rules on levels of democracy over time (19).

The book is structured in eight chapters. The introduction presents and justifies the relevance of the topic. Then chapter 2 explains the research design and quantitative analysis. For her quantitative analysis, McClintock takes into account as indicators of “democracy” the Freedom House index (political rights and civil liberties) and the Varieties of Democracy (V-Dem), as well as voter turnout. Countries are qualified as majority runoff (minimun threshold), qualified runoff (40–50 percent), plurality (no threshold), and qualified plurality (below 40 percent). This section also discusses whether presidential election rules affect levels of democracy or other independent varibles are at work (21). Amid these concerns, the author is honest in recognizing the limitations of the quantitative analysis.

Chapter 3, “Why Was Runoff Superior? Theory and Cross-National Evidence,” focuses on the main arguments in favor of and against both sets of rules to show that the number of parties under plurality is larger than expected, while some of the risks of runoff were not proven by the empirical evidence, particularly a larger number of outsiders and voter fatigue. Besides that, in plurality systems, legitimacy problems are observed, while several elections under runoff lead to a second round in uncertain contexts, proving the relevance of this system to increasing legitimacy.

The following four chapters are devoted to presenting results and developing a detailed analysis of cases. These chapters are organized according to the clusters of countries created by the electoral rules. Chapter 4, “Plurality,” introduces the problems of plurality based on the experiences of Honduras, Mexico, Nicaragua, Paraguay, and Venezuela, where the rule was complicit in vicious circles of deleterious elections won with less than 41 percent of the vote. It also discusses the exception of Panama.

Chapter 5, “Runoff,” focuses on the successes of runoff in Brazil, Chile, the Dominican Republic, El Salvador, and Uruguay, where democracy generally improved and the system helped to incorporate the left. Of course, the picture coming from case studies is not crystal clear. For instance, in the Dominican Republic, runoff was introduced in 1995 and had an immediate, positive effect on levels of democracy, but a reversal came later. It invites us to think about what determines institutional change and to what extent new scenarios influence out-comes over time.

Chapter 6, “Runoff: Amid a Plethora of Political Parties,” introduces the cases in which runoff coexists with the expected negative outcome of such an electoral rule: an increase in political parties. The cases are Colombia, Ecuador, Guatemala, and Peru. Case studies shed light on processes but also can open room to support alternative arguments. Here, then, the inferior levels of democracy for Colombia and Guatemala are explained not by electoral systems but by political violence (139). One can ask to what extent the same could apply to some of the plurality countries. This chapter offers a good overview of the relevance of the context in which an electoral rule emerges, and this refers not only to all actors but also to other rules.

Chapter 7, “Runoff: Is a Reduced Threshold Better?” discusses a potential improvement of runoff, the reduced threshold (for example, 40 percent with a ten-point lead, as in Argentina) in the two cases in which such a complement is available, Argentina and Costa Rica. Two other countries recently adopted or modified a runoff rule, Bolivia in 2009 and Ecuador in 1998, also choosing a 40 percent threshold with a ten-point lead. Nicaragua is one of these cases as well. However, given that the number of elections has been insufficient to provide a test, these three countries are not analyzed.

As the main finding, even if not definitive, McClintock considers the reduced threshold risky. The empirical evidence shows that it avoids runoffs that would have been unnecessary, but also the ones that would have added presidential legitimacy. In her words,

In the “Conclusion and the Future of Presidential-Election Rules,” McClintock afirms that “no electoral rule is a magic bullet. No electoral rule is without its negative implications. No electoral rule operates independently of a country’s set of electoral rules. Still, runoff is superior to plurality” (193). The only plurality country sustaining high levels of democracy since 2000 is Panama, while in Honduras and Venezuela, plurality blocked the emergence of leftitst parties, with the consequence of promoting polarization later on. On the other side, runoff countries, although with remarkable diversity, performed better. However, as Gabriel Negretto has pointed out in his rigorous study of constitutional choice in Latin America (Making Constitutions: Presidents, Parties, and Institutional Choice in Latin America, 2013), quoted in the book, a key determinant of institutional change is the strategic interest of the relevant political actors. This does not mean that electoral rules are designed to hurt democracy, because some actors also believe that the new rule would work better. But contexts and power equilibriums matter, and what explains a given institutional change could also explain its success.

The book considers the potential for the superiority of runoff to travel beyond Latin America; a subsection discusses the potentialities of the system for the United States. Further discussion of the pros and cons of runoff should take into account a more volatile electoral scenario, influenced by digital media and extreme right ideologies. If, during the Third Wave, a key challenge was the incorporation of leftist political leaders into the democratic political arena, it seems that nowadays the key challenge is to deal with an emerging extreme right, already in power in Brazil. If runoff proved to be relatively satisfactory to include new parties moderating the left, it is not so clear what will happen from now on.