One defining feature of America’s legislative branch is that it is designed with bicameral chambers. Further, unlike other democracies, the United States distinctively has two chambers that are, for the most part, equal. Despite the uniqueness of America’s bicameral legislature, there has been limited scholarly attention regarding bicameralism’s impact on its lawmaking process and policy outputs. Josh M. Ryan’s The Congressional Endgame: Interchamber Bargaining and Compromise is one of the first scholarly efforts to examine how bicameralism can influence the amendment process, conference committees, and policy outputs. During an era of high partisan polarization, this innovative and original research provides rich and detailed insights into the inner workings of Congress.

The author’s research question is relatively simple: How does bicameralism affect postpassage bargaining on a bill? Relying on a noncooperative bargaining model, Ryan argues that the winning coalitions in the House and Senate fight for their portion of the benefits that would be derived from reaching a compromise. The two chambers can also receive benefits from other political actors, such as interest groups, for not reaching an agreement on a bill. If the benefits for disagreeing on a bill are greater than the benefits associated with agreeing to the bill, then the bill will most likely not be enacted into law. Further, Ryan asserts it is highly costly for the chambers to resolve their differences over a bill; for example, because of scarce floor time. Although both chambers usually benefit by any division of the benefits, they frequently disagree on the size of benefits that each chamber receives. Taken together, Ryan’s theory posits that the potential benefits a chamber receives from agreeing or disagreeing over a bill, in conjunction with the costs associated with bargaining, should influence the following: acceptance/rejection of a bill, postpassage bargaining venue selection, probability of bill failure, and policy outcomes. Using this theoretical framework, Ryan develops several theoretical expectations.

The empirical chapters rigorously test the precise theoretical expectations that are derived from this theoretical framework. All the data analyses are carefully and meticulously conducted. In chapter 4, Ryan explores which bills are sent to the postpassage bargaining stage. Additionally, he examines the factors that incentivize Congress to bargain with a conference committee or by amendment trading. He answers both of his research questions by examining a subset of bills from the 93rd to 111th Congresses and uses selection and logistic models. The results indicate that legislative proposals with few backers in the chambers are less likely to proceed to the postpassage bargaining lawmaking stage because they are too costly and time consuming to address. Chambers with less ideological cohesion are also less likely to advance a bill to the postpassage bargaining stage. Regarding whether the chambers prefer to use a conference committee or amendment trading in the postpassage bargaining lawmaking stage, Ryan interestingly finds that the House and Senate are driven by different political factors. The Senate tends to prefer that a bill be resolved by a conference committee, rather than by amendment trading. because the minority party can more easily obstruct and waste valuable floor time during amendment trading. Conversely, in the House of Representatives, Ryan finds that, as support for a bill decreases, the probability of a bill being sent to a conference committee increases. This is because a bill with fewer supporters in the House tends to increase the cost of legislative activity on the floor.

Chapter 5 explores how much discretion the conferees have when bargaining over a bill. Ryan finds that conferees tend to employ substantial discretion when they craft a compromise bill. He uses two measures of conferee discretion: the percentage of members who switch their vote from the initial passage to conference passage on a subset of bills and whether a bill failed in the conference stage. Overall, Ryan finds that vote switching tends to occur more frequently in the ideologically extreme chamber, because they are forced to compromise with the more moderate chamber, which is more likely to reject a bill. Additionally, he finds that a bill is more likely to fail in the conference stage if there is a slim majority of support within the chamber.

Chapter 6 is a fascinating analysis of the policy change that occurs between a bill’s initial passage in a chamber and after consideration by a conference committee. Ryan tests multiple and competing legislative theories with three measures of change: in coalition size, in minority support, and in ideological extremity. These measures capture the change that a bill undergoes within this lawmaking process. The main conclusion from this chapter is that the more moderate chamber tends to be more effective than the extreme chamber in shaping legislation in the conference stage. Specifically, a bill tends to become more ideologically moderate relative to the more extreme chamber. However, Ryan also provides evidence that suggests that a bill becomes slightly more ideologically extreme relative to the more moderate chamber, but the moderate chamber tends to have the upper hand. Intriguingly, the data show little support for the notion that bills become more partisan in the conference stage.

Chapter 7 analyzes bill failure and policy change for a subset of bills that are resolved by amendment trading. Overall, Ryan finds that amendment trading and conference committees have similar dynamics. Bills from the more ideologically extreme chamber tend to become more moderate through the amendment trading process, whereas bills from the moderate chamber tend to become more extreme after amendment trading. This interesting finding challenges the partisan theory of congressional politics by suggesting that amendment trading does not produce more ideologically divisive legislation.

This remarkable book contributes to the field of congressional politics by providing an in-depth analysis of how bicameralism affects the legislative process and policy outputs. It convincingly demonstrates that bicameralism does indeed tend to produce more moderate policies as envisioned by the framers of the Constitution. It also provides persuasive evidence that moderate chambers tend to be more successful in shaping legislation in the final lawmaking stage, at least relative to the more extreme chamber. This empirical finding offers numerous and useful insights into public policy.

Several interesting future research questions emerge from the findings of this impressive book. For example, how might legislative capacity affect the impact of bicameralism on policy change within a bill? It is certainly possible that the chamber with greater resources might be more successful in shaping legislation. Thus, future scholars should explore whether differences in policy expertise and information can influence the success a chamber has in the postpassage bargaining lawmaking stage. Additionally, future research should explore in greater detail how the executive branch influences the effect that bicameralism has on a bill. Finally, scholars should strive to create more precise measures relating to the changes a bill undergoes in the postpassage bargaining stage. The book relies on indirect and proxy measures of bill change. Finding more accurate measures will be no easy task, but it is one that will most likely enrich our understanding of legislative politics. In sum, this book is a springboard for a plethora of future research ideas.

The Congressional Endgame is an outstanding book that fills a much-needed empirical and theoretical gap. Its findings should be taken into account by students of congressional politics as we seek to understand the policy implications of bicameralism.