If it can be said that for at least the last decade much of the field of comparative politics has been focused on demonstrating that institutions matter, then Bruce Gilley's well-written and tightly argued new book persuasively shows that the legitimacy of those institutions matters. In particular, while a generation ago comparativists managed to “bring the state back in,” Gilley picks up where Max Weber left off a century ago and attempts to bring the legitimacy of the state back in. Indeed, he calls legitimacy “one of the greatest ‘omitted variables’ in contemporary political science” (p. xii). This important book is a corrective that should be widely read.

Gilley's approach to the study of legitimacy is comprehensive, beginning with a rich and illuminating definitional exercise, moving on to an empirical effort that scores 72 countries worldwide on their level of legitimacy. The book explores legitimacy's origins and impacts, both internally and internationally, and it also includes a chapter-long case study of Uganda.

It will surprise many to learn from this book that as far back as 200 b.c., emperors in China were concerned with establishing their legitimacy, as have been dictators and democrats ever since. Legitimacy for Gilley, therefore, is not confined to democracies, but is a problem for states in general. His core definition of the concept, reflected in the title of the book, is “rightful rule.” For rule to be rightful, it must at least to some degree 1) be legal, 2) rest on shared norms of conduct, and 3) involve consent of the governed. Since he eschews, indeed rejects, the crude legitimate/illegitimate dichotomization so often heard in the popular press (e.g., “President X is so unpopular that his regime lacks any legitimacy”), his approach is to use these three dimensions to build a continuous indicator.

Fundamental to the view of legitimacy explored here is that it is measured from the perspective of citizens. States are seen as neither inherently legitimate nor illegitimate. Rather, citizens through their opinions and actions determine precisely how legitimate their system is. Given this definition and approach, it is not surprising that Gilley rejects conceptualizations of legitimacy that focus on elites alone. He is aware, however, that some citizen views and behaviors almost certainly count more than others. In developing countries with strong military men who do not believe that elected officials are legitimate, one would expect that it is the military that literally “call the shots.” But Gilley argues that one cannot know a priori which citizen views will matter more. Indeed, while the military might count for a lot, protestors, guerrillas, and terrorists groups might count for more.

The Gilley legitimacy index draws on two main sources for its construction. First, it uses regional survey data to measure the legality and justification dimensions. For these measures, the author uses questions that tap into citizen satisfaction with democracy, confidence in the bureaucracy, evaluation of the current political system, and so on. To measure the dimension of the consent of the governed, he looks at voter turnout and payment of “quasi-voluntary” taxes, such as taxes on income, profits, capital gains, and so on, as a percentage of total central government revenues. The combined measure is weighted, by increasing the justification dimension's contribution to the overall index to 50% of the total, allowing the other two dimensions to count for only 25% each.

The data available allow Gilley to score legitimacy in 72 states, countries that collectively contain over 80% of the world's population. While this list is expansive, he acknowledges that it underrepresents smaller, poorer states about which there are insufficient data to provide a reliable score. The final index, based on a 0–10 scale, not surprisingly finds Nordic countries at the top, with Denmark and Norway at 7.6; the Netherlands, Canada, and Austria are the only other countries to score 7 or above. The United States scores 6.8, and most other advanced industrial societies also do very well. The bottom of the list finds Russia, Pakistan, and Armenia scoring below 3. Regionally, the “West” scores very high compared to all other world regions, followed by Asia and Africa, and, at a much lower level, the Middle East and Latin America. Eastern Europe lies at the very bottom. It must be kept in mind, however, that the book includes only the years right before and after the new millennium (1996–2002), and so it may well be that important changes have occurred since then.

Gilley next turns his attention to the sources of legitimacy. After a nuanced argument about the potential origins of legtimacy, he presents a long list of simple correlations between his legitimacy index and those possible sources. Variables such as governance (based on the World Bank Institute governance indicators) and income and welfare levels exhibit the highest correlations. He argues that essentially three dimensions—governance, democracy/rights and development—are the main sources of the legitimacy of states. The book then moves into an elaborate discussion of how states gain legitimacy over time. Central to this process, as Seymour Martin Lipset argued long ago, is their performance and their ability to deliver improved social conditions. This discussion becomes contextually grounded in the case of Uganda, which scores 5.05 on Gilley's index. The case study shows how countries can gain and lose legitimacy.

The final substantive chapter of the book looks at the consequences of legitimacy. This is a far-ranging discussion that supports the initial contention that legitimacy matters a great deal. Gilley finds that “[w]rit large, the concept of legitimacy proves to be a parsimonious and powerful explanation of many political phenomena from state failure to democratization and multilateral cooperation” (p. 206).

The Right to Rule will likely be most satisfying to those who prefer theory to quantification. Nearly all of the key quantitative information has been relegated to a detailed online appendix found at the author's Website. That appendix runs to 50 pages, and no doubt the publisher balked at including all of it. Yet this reader would have preferred at least a small portion of the online appendix to have been included in the book, especially the listing of the nine key variables that make up the Gilley index, their sources, their means, and standard deviations. Indeed, such a table, included in the online appendix, takes up only a few pages. A second limitation, which also could have been dealt with by including more tables in the book, is that the reader does not learn how each of the three main components of the index behaves. Since Gilley and others (John A. Booth and Mitchell A. Seligson, The Legitimacy Puzzle in Latin America: Democracy and Political Support in Eight Nations, 2009) clearly recognize the multidimensional nature of legitimacy, one is frustrated at not having learned the distinct origins and consequences of each of those dimensions.

Despite these concerns, one cannot come away from reading this fine study without acknowledging that legitimacy does indeed matter and that it needs far more attention than the field has accorded it.