What are the main factors that allow presidents and prime ministers to enact policy through acts of government that carry the force of law? Or, simply put, when does a government actually govern? The theory presented in this book provides a major advance in our understanding of statutory policy making. Using a combination of an original analytical framework and statistical techniques, as well as historical and contemporary case studies, the book demonstrates that, contrary to conventional wisdom, variations in legislative passage rates are the consequences of differences in uncertainty, not partisan support. In particular, it shows that a chief executive's legislative success depends on the predictability of legislators' voting behavior and whether buying votes is a feasible option. From a normative standpoint, the book reveals that governability is best served when the opposition has realistic chances of occasionally defeating the executive in the legislative arena.

“This is an excellent book! It offers a theoretical explanation for a phenomenon that cannot be accommodated by existing models of legislative action: why democratic governments sometimes get defeated in the legislature (it has to do with uncertainty about legislators’ preferences). The theory developed in the book is brought to the data in a rigorous and creative way, with the use of multiple methods and datasets. The book contains many interesting and provocative claims, including the idea that vote buying is almost inherent to legislative action; that vote buying is often efficient; and that there area circumstances in which governments may rule too much. In short, Ruling by Statute is an important book that represents the best in political science.”
– José Antonio Cheibub, University of Illinois at Urbana-Champaign

“This outstanding book puts the study of executive-legislative interaction over lawmaking where it belongs: in a context of strategic interaction under uncertainty. This is a rich, wide-ranging and eye-opening analysis of a topic that is central to understanding how democracies work.”
– William R. Keech, Duke University

“In Ruling by Statute, Sebastian Saiegh challenges the conventional wisdom concerning law making that either agenda-setting powers and/or partisan whipping and voting cohesion are essential to a chief executive's power to make law. Instead, relying on positive political theory, statistical analysis, and country case studies, Saiegh provides a major advance in our understanding of how inter-branch bargaining affects lawmaking, showing, for example, that the unpredictability of legislators’ voting behavior is actually key in limiting or shaping a chief executive’s ability to successfully enact new laws. This book should be on the reading list in every course on democratic theory or comparative politics.”
– Matthew D. McCubbins, University of Southern California