[A list of all publications and datasets referenced below is available here]
Constitutional Design
Most of my research on constitutional design centers around the Comparative Constitutions Project (CCP), a project that I conceived with Tom Ginsburg while we were colleagues at the University of Illinois.  The heart of the project is a set of data on the content of historical constitutions.  Our 2009 book, the Endurance of National Constitutions, which we wrote with our stand-out graduate student James Melton and collaborator, is the first book-length product from this project.  I have a growing number of other papers on constitutional design, which draw from our ever-expanding CCP enterprise.  This writing includes work on the process of writing constitutions, the consequences of limiting the terms of executives, a reconsideration of the utility of the classic distinction between Presidentialism and Parliamentarism (with Jose Cheibub), the peculiar species of constitution written under military occupation, the effect of international human rights covenants on the menu of rights in national constitutions (with Beth Simmons), as well as working papers on the measure of a host of important Political Science concepts (such as the ease of constitutional amendment, judicial independence, and federalism).  I am also currently completing a book on the diffusion of constitutional ideas, which draws from my Phd dissertation, but more on that below.
I have also been involved in a number of sporadic efforts to assist drafters of constitutions in various parts of the world.  Most of this work involves providing drafters with menu of reasonable options for any given set of provisions along with some expectation of the various consequences of these design choices.  In September of 2013, we (with Google) launched Constitute, a website that allows constitutional drafters, citizens, (and anybody with some curiosity about constitutions) to extract excerpts of constitutional text on some 300 topics from a complete set of constitutions currently in force.  The website has undergone three large step-changes and we have big plans for more. In December of 2014, we introduced an Arabic version of the site and we have plans to introduce a Spanish version in 2016. Constitute replaced, a site we developed and maintained for five years and which included a repository of constitutional texts, reports on options, and a blog.  That blog has evolved to become the official blog of the International Journal of Constitutional Law. Some of the original option reports are available upon request.
A significant research theme that runs through most of my work has to do with the spread of ideas and policies through some process of contagion.  My Ph.D. dissertation explored the diffusion of democracy and I have looked at the mechanics of diffusion in a number of different substantive arenas, such as economic policies, investment treaties, and of course, constitutions.  Indeed, my primary motivation for collecting data on historical constitutions was to describe the various spatial and temporal patterns by which constitutional ideas spread.  Those patterns are, in part, the topic of my book (Designed by Diffusion), which I hope to be on the shelves within the year.  The book includes about eight years of research on the diffusion of constitutional ideas and draws from three areas of research: (1) a cross-national study of the spatial and temporal patterns of design choices in historical constitutions; (2) evidence from interviews and archival data from Brazil; and (3) a series of laboratory experiments that test the micro-foundational assumptions of theories of institutional diffusion.  Some of the conceptual ideas in the book are assembled in this article.
National Identity
I have a deep interest in citizens' attachment to the state, sometimes conceived as nationalism or patriotism.  I view some level of attachment as a critical ingredient in stitching together otherwise divided states.  With Rui de Figueiredo I wrote an article on the connection between in-group and out-group pride, which explored whether individuals who express strong positive feelings toward their country are also hostile towards immigrants and other outsiders (not really, it turns out).  With John Sides, I have been investigating the institutional bases of national attachment.  In our recent article in APSR we look closely at multiethnic states and whether certain institutions (e.g., those that promote powersharing) inculcate an attachment to country among minority groups (unfortunately, for the most part they do not).  In most of our work, Sides and I have been using extant measures of individuals' national identity, which are illuminating but, in our view, sub-optimal for a variety of reasons.  We have, therefore, been developing a set of original survey items and exploring a number of experimental methods to better measure national identity and to better understand the consequences of certain institutions on national (and ethnic) identity.  Increasingly, we have come to view citizenship policies as potentially the most consequential policy lever for fostering national identity, but we have yet to firmly establish this.  We have a grant proposal that, if ever funded, will allow us to test our new empirical approaches with national samples in several multiethnic states.  I also have a long-running project in which I have been studying unobtrusive measures of national identity in the U.S. context.  This includes a periodic survey of sampled households within a municipality in the midwest on the the incidence of flag displays (and other patriotic symbols) as well as campaign yard signs -- data that I have paired with surveys of these households, turnout data, even some quasi-experiments to test a variety of hypotheses about national identity, ethnocentrism, and even diffusion.  In recent years, Brian Gaines has joined me on this project.
Latin American Politics
I have long had a keen research interest in Latin America through residency (Guatemala, Colombia, Peru, Brazil) and field work in the region.  My original academic interests are in Central American politics and I have some early work on the topic that I may dust off and publish one day (if time has been kind to it).  In the last ten years, I have been particularly focused on Brazil.  Some of my research on Brazil has been published in Brazilian journals, such as an article on mandatory voting and one on the Brazilian constitution.  In Summer of 2010, I will return to Brazil to conduct another wave of interviews with elites, scholars, interest groups, and journalists about the making of the Brazilian constitution.  I had conducted a set of such interviews in 2001.  Footage from these interviews will be included in a documentary film on the topic that I plan to make (with a Brazilian filmmaker and Tom Ginsburg). Here's a trailer.
I have a strong interest in social science methodology and teach courses on statistics and research design and have published some on issues of conceptualization and measurement.  One of my earliest publications is on the measurement of democracy and much of my other published work includes a significant measurement component.  Recently, I have become particularly interested in the problem of measurement equivalence, or how researchers can develop measures of concepts that are comparable across time and space.  With John Sides I have been working on methods to diagnose and treat issues of measurement non-equivalence.  Some of this will appear the publications page soon.