1. Multidimensional Politics: My main research program has sought to move beyond the assumption of unidimensional politics (e.g., left vs. right or liberal vs. conservative) in order to improve our understanding of legislative politics. As demonstrated by the co-existence of both social/cultural and economic dimensions in US politics, legislative politics is often better characterized by multidimensionality. For this, my research has combined the development of the spatial model with advances in the measurement of legislators’ preferences and policy outcomes/locations (PA 2008). With these measures, I have applied the spatial model or social choice theory—such as the core, uncovered set, and winset—to deepen our understanding of the dynamics of legislative negotiations (APSR 2009; PRQ 2013), the choice of legislative procedures (JOP 2014), the determinants of policy outcomes (JLEO2009; Public Choice 2017), and the dynamics of party realignment (AJPS 2011). My most recent project in this program extends the decision-making framework from simple majority to supermajority (Public Choice 2017) to examine the process of Senate treaty-making. Currently, I am working on projects that incorporate presidential veto, filibuster, and bicameralism into the analysis to extend unidimensional models of congressional lawmaking, such as the pivotal politics model, to multidimensional settings.

2. Congress and Foreign Policy: I have been working on several projects related to the role of the US Congress with regard to defense and foreign policy. I have measured legislative preferences on various foreign policy issues (ISQ 2009; PRQ 2013; PSRM 2018). I then have used these measures to examine party polarization on trade (ISQ 2009), foreign and defense policy (APR 2019), and the dynamics of relations between the majority party and the House Armed Services Committee (Working Paper). Currently, I have a series of projects that examine how Congress has exercised its power of the purse—specifically, policy riders on foreign and defense spending bills—to affect foreign and defense policy. I also have projects that examine the influence of isolationism on US foreign policy before WWII.

3. Party politics in Congress: My research has contributed to our understanding on party realignment and polarization. In particular, I have examined how political parties have changed their positions on immigration (AJPS 2011), how political parties have become polarized with regard to trade (ISQ 2009) and foreign and defense policy (APR 2019), and how the cohesion of the majority party has affected its relationship with a constituency committee, such as the House Armed Services Committee (Working Paper). My work forthcoming at APR has found that the major political parties switched their positions on foreign and defense policy in the late 1950s and 1960s. I plan to examine how the parties changed their positions on foreign and defense policy in the context of the multidimensionality of foreign policy viewpoints (that is, how the change was facilitated by the shift of the main dimension from issues of nationalism vs. internationalism to those of unilateralism vs. multilateralism).  

4. Legislative Politics of Bureaucratic Delegation: I have been working on projects which explore how legislators affect both the independence and performance of bureaucracies. In Jeong,Miller, and Sobel (2009), we examine how negotiations among legislators representing diverse interests contributed to the creation of the Federal Reserve. In Jeong (2016), I explore the ways in which legislative incentives to seek a personal vote and legislative specialization on legislative committees affect the performance of bureaucracies beyond the US case.

5. Legislative Politics in Korea: In an effort to shed its negative image, the National Assembly of Korea reformed its lawmaking process in 2012. The main thrust of the reform was to boost consensus-building in the lawmaking process by requiring a supermajority to pass controversial legislation. This provides a valuable opportunity to examine the effects of supermajority rules using a case other than the US Senate. I started working on projects on legislative politics in Korea.