The increasing polarization of American politics is not a new topic, but the effects of this development on the treaty process have been overlooked by scholars. Jeffrey S. Peake corrects this oversight. In Dysfunctional Diplomacy: The Politics of International Agreements in an Era of Partisan Polarization, he deftly examines how deep partisan divisions have broken the treaty process and led presidents to rely even more on their unilateral executive authority to complete international agreements.

All presidents completed more unilateral agreements than treaties in the second half of the twentieth century. But as Peake demonstrates, during the Obama administration, a significant transformation occurred. Because of partisan polarization, not only did Obama submit fewer treaties to the Senate for approval but also his success rate in getting treaties ratified was the lowest of any modern president, resulting in “the worst treaty record in modern history” (p. 16). That a polarized political environment would make ratifying treaties more difficult intuitively makes sense, especially considering that a treaty requires a supermajority of two-thirds of the Senate to pass. Indeed, bipartisan majorities become more difficult as polarization increases. Yet, as Peake explains, the issue is more complex than that. As noted, presidents completed most of their international agreements through executive agreements in the second half of the twentieth century. However, on the most significant issues, they still routinely used treaties. The Obama era marked a departure from that norm. He and his successors have essentially ceased to use treaties, even for the most substantial agreements, and have instead relied almost exclusively on their unilateral authority.

Peake has written extensively on the treaty process and the politics involved, including in his previous book, coauthored with Glen Krutz, Treaty Politics and the Rise of Executive Agreements (2009). That book took a more positive view of executive agreements than does Dysfunctional Diplomacy. It argued that the expansion of executive agreements was mainly about efficiency and a way for presidents to deal with the new demands of global leadership. The twentieth century saw plenty of partisan conflicts, but established norms made the treaty process work. Peake argues that is no longer the case: “The domestic politics of international agreements are fundamentally broken, and demonstrate the cost of partisan polarization and presidential unilateralism” (p. 124).

Presidents are still pursuing their foreign policy agenda in this new reality, but the “implications for treaty dysfunction are severe” (p. 2). Domestically, Congress’s failure to challenge presidential unilateralism in this area has helped erode the nation’s system of checks and balances. Internationally, the almost exclusive use of executive agreements has made the United States less reliable. Many international partners prefer treaties to executive agreements, believing that they signal a stronger commitment because they require broad domestic support. So, the recent trend of forgoing treaties almost entirely makes the United States a less credible partner. The dysfunctional treaty process also deprives the United States of influence in shaping international law. At the negotiation stage, US officials’ ability to influence multilateral agreements is limited because other nations are hesitant to make concessions, given the low odds that the Senate will ratify the treaty. Moreover, when the United States remains a nonparty to multilateral treaties, it then lacks the ability to affect the rules on major global issues.

The book begins by providing a brief history of international agreements and distinguishes among various types: Article II treaties that need Senate approval, executive agreements that do not, and political commitments in which a president commits to undertake a particular action but it is nonbinding. The rest of the book is a mixed-methods study that provides detailed case studies with original data on one thousand treaties and more than three thousand executive agreements. Chapter 2 looks at recent trends in international agreements. It focuses on the vastly different politics faced by George W. Bush with the Moscow Treaty in 2002 and later by Obama with the New START treaty in 2010. Historical trends in presidential treaties and executive agreements are also discussed. The main takeaway is that the number of treaties submitted by Obama and his success rate in getting treaties approved by the Senate were both far lower than his predecessors. For example, the treaty approval rate for presidents from 1949–2016 during their administrations was 76.6%; for Obama it was 35.9% (p. 26).

Chapter 3 provides an empirical analysis that evaluates the effects of polarization on the domestic politics of treaties over a 70-year period. It demonstrates that as partisan polarization increases in the Senate, presidents rely less on treaties to conclude international agreements. It also shows that an increase in partisan polarization results in increased delays in the treaty approval process and highlights the importance of the committee stage in explaining treaty gridlock.

Chapter 4 is a collection of fascinating case studies that look at significant multilateral treaties that the United States has not ratified in the areas of human rights, the environment, and arms control. They illustrate the severe domestic political challenges presidents face in the treaty process. Peake explains that one of the central arguments made by opponents of multilateral treaties is that they threaten US sovereignty, a claim he finds “particularly weak” (p. 57). Chapter 5 focuses on executive agreements using a dataset of more than three thousand publicly reported executive agreements from 2005–20. In the period under consideration, security agreements made up the largest percentage of executive agreements (44.7%), followed by economic agreements (30.1%), and cultural, educational, and scientific agreements (15.9%; p. 85). Peake also finds that the United States has completed executive agreements with a range of nations, including almost all members of the United Nations, and most agreements have been bilateral (p. 87). Chapter 6 is about political commitments and their central role in US diplomacy. However, despite their importance, they have limits, which are illustrated through case studies on the Iran nuclear agreement and the Paris Agreement on Climate Change, two deals often described as executive agreements but that are really political commitments.

Overall, Dysfunctional Diplomacy explains a development that has major implications for America’s engagement with the world and the health of its democracy. Peake clearly illuminates the challenges and where the greatest fault lines lie: he concludes his book by offering sensible suggestions about how the dysfunction in the treaty process might be ameliorated by once again giving Congress a voice in international agreements and enhancing its ability to check presidential unilateralism. Congress is unlikely to act, but Peake’s rich analysis shows why they should and exposes the consequences of continued inaction.