In The Collision of Political and Legal Time: Foreign Affairs and the Supreme Court’s Transformation of Executive Authority, Kimberley L. Fletcher sets out to explain how the Supreme Court, over the last century, has decided key cases concerning executive authority in foreign affairs. Moving beyond a singular focus on one of the three canonical models of judicial decision making—the legal, attitudinal, and strategic models—Fletcher contends that justices must weigh both internal factors like established legal norms and external factors—such as social forces, the political landscape, and national security threats—when deciding whether to expand or contract presidents’ foreign policy powers at critical moments.

In analyzing the Supreme Court’s decision making in these cases, Fletcher highlights its ability to create a “new constitutional order” (p. 11) for interpreting the president’s proper legal and constitutional role in foreign affairs. In other words, the outcomes of such cases can usher in a new regime that shapes how future courts and other political actors define the limits of executive power. Such precedent, however, is not irreversible. Instead, she argues that exogenous shocks can lead to the emergence of new transformative cases that can once again create opportunities to redefine the boundaries of executive authority in particular areas.

To provide evidence for her claims, Fletcher conducts cases studies on a handful of the most important Supreme Court decisions involving executive authority in foreign policy throughout the twentieth and twenty-first centuries. These cases consider challenges to a wide range of presidential actions, such as foreign trade embargos (United States v. Curtiss-Wright, 1936), Japanese internment (Hirayabashi v. United States, 1943; Korematsu v. United States, 1944), the seizure of steel mills (Youngstown Sheet & Tube Company v. Sawyer, 1952), freezing Iranian assets (Dames & Moore v. Regan, 1981), restricting travel to Cuba (Regan v. Wald, 1984), and the detaining of enemy combatants (Hamdi v. Rumsfeld, 2004; Boumediene v. Bush, 2008). In analyzing these cases, she provides an impressive array of rich detail surrounding the impetus for the initial challenges; the social, legal, and political context at the time the cases were decided; the most relevant factors in the justices’ deliberation; and their long-term consequences.

Fletcher indeed finds that the Supreme Court’s decisions in these pivotal cases were based, at least partially, on external conditions and also created new precedents that dictated the parameters of executive authority in foreign policy. In the midst of war between Bolivia and Paraguay, for instance, the Court relied on the “sole organ” doctrine in United States v. Curtiss-Wright (1936), which consequently ushered in a newly expansive interpretation of the president’s independent role in conducting foreign affairs. Executive power was further bolstered following the decisions in Hirayabashi v. United States (1943) and Korematsu v. United States (1944), when the Supreme Court upheld President Franklin D. Roosevelt’s executive order leading to the internment of Japanese Americans in World War II. In those rulings, the Court claimed that such orders were justified in that particular context for the sake of protecting the national interest during national emergencies.

Although the outcomes of these cases were crucial for shaping future opinions regarding executive authority, they were not immutable and certainly did not lead to a blanket increase in executive power over time. Contrary to conventional wisdom, the Court subsequently decided key cases that produced serious limitations on presidential foreign policy powers at critical moments. In the immediate post–9/11 era, for instance, the Supreme Court determined in a series of cases that national security interests did not warrant many of George W. Bush’s actions regarding detainees, which it found violated individual rights guaranteed by the Constitution.

Across all of the cases she examines, Fletcher finds that the Court relied heavily on its evaluation of pressing external conditions, often in contradiction to the justices’ own ideological preferences, to determine whether executive power should be expanded or restricted. In doing so, she contributes to—and challenges—a political science literature largely focused on the partisan or ideological alignment of institutional actors when analyzing judicial outcomes. She demonstrates that there is a constellation of germane factors that affect judicial decision making in foreign policy, an area where presidents have the greatest potential to exercise their most expansive and consequential powers.

Notwithstanding these contributions, the book would have been further enriched had Fletcher incorporated much of the existing separation-of-powers literature into her perspective. Although the legal norms and various exogenous conditions, such as national security, emphasized here are no doubt important for judicial decisions, institutional factors may also be at work in these cases. Justices who care about the legitimacy of the Court may be deterred in ruling against the other branches of government if they believe retaliation is imminent. Congress can sanction the judiciary through court-curbing legislation, and the executive branch can choose not to enforce its rulings.

Of course, the likelihood of these threats may be determined by the degree to which the three branches of government agree or disagree over policy. Ample resources of funding or staffing, internal cohesiveness, and favorable public opinion can likewise empower Congress and the executive branch to retaliate against the Supreme Court, thus making justices less likely to rule against these political actors under such conditions. In these cases, the Court may rely more heavily on the imperative social or international context to justify expansions of executive power, rather than on the legal norms that are potentially being violated. Future studies could further examine the conditional relationship between these various factors when developing theories of judicial decision making.

Finally, researchers should use the insights provided by this book to study the exercise of presidential power over time. Have presidents and other executive branch actors moderated their actions based on the prevailing norms of executive authority established by the Supreme Court during particular time periods? Does this executive behavior change or correspond to the key cases Fletcher identifies that redefine such authority? And may limitations or expansions of executive foreign policy power have implications for the executive’s domination in domestic policy areas as well?

Overall, Fletcher provides a firm foundation in The Collision of Political and Legal Time for answering these and other questions on which future work could fruitfully build. She provides one of the most thorough and in-depth treatments of Supreme Court cases concerning executive authority in foreign policy to date. There is no doubt that these case studies will serve as a vital reference point for students of judicial politics, executive power, foreign affairs, and American political development.