The rules and norms governing world politics are constantly changing. Understanding why and how this is so has become subject to an ample and lively body of scholarship during the past two decades. Much of the literature that grapples with the operation of norms in international politics assumes that normative systems remain stable until they are interrupted by exogenous factors that produce episodes of change. Explaining instances of norm change thus becomes the main task of analysis. Change is, in turn, often traced back to the conscious manipulation by actors (whether states, international organizations, international social movements, or transnational advocacy networks) or to the destabilizing effects of major wars or other disruptive events.

Prohibiting Plunder and International Norms and Cycles of Change both belong to a smaller body of work that assumes change to be inherent to and continual in normative systems. As Wayne Sandholtz puts it, “change is an inherent feature of all normative systems as general rules collide with the infinite particularity of social life, and people must argue about how the two should mesh” (p. 3). Like others before them, these books also point to tensions and contradictions among normative principles as a source of alteration. Approaching norms as dynamic and in continual transformation, the analytical task consists of tracing change over longer periods of time. Some scholars have done so genealogically, by centering on broader discursive changes and historical contingencies, with norms changing “‘in piecemeal fashion’ out of the vicissitudes of history” (Richard Price, The Chemical Weapons Taboo, 1997, p. 7). Others, including the books under review, have done so by analyzing formal arguments and counterarguments about standards of behavior over time.

Both of these books advance Sandholtz's “cycle theory of change,” which seeks to capture the dynamism of international normative frameworks. A cycle begins with the assemblage of existing norms, the rule structures that guide actor choices, behaviors, and justifications. Actions—particularly in the context of major events such as wars, revolutions, or collapse of empires—inevitably give rise to disputes about the relation between behavior and existing norms, and the ensuing arguments in turn modify the norms under dispute and transform the rule structure. Cycles of change are thus traced through the following steps: existing normative frameworks → (lead to) actions that trigger disputes → arguments about which norms apply and what norms permit or require → modified normative framework (which is the start of a new cycle). Arguments that are a) accepted by the world's major states, b) consistent with the “foundational metanorms” of the “liberal Western tradition,” and c) supported by multiple, recent precedents are presumably more likely to prevail. With such cycles ubiquitous, norms are in a constant process of transformation. Although the work of Margaret Archer is not mentioned, the sequence is reminiscent of her morphogenetic cycle (Margaret Archer, Culture and Agency: The Place of Culture in Social Theory, rev. ed., 1996). That said, and while the individual pieces that go into the cycle theory may not be novel when read against the existing norms literature, the model is quite useful as a simple heuristic device to trace changes in arguments over time.

While the books share this model, they part ways empirically. Prohibiting Plunder traces the evolution of norms against wartime art plunder, covering 200 years of debates and several turns through the norms cycle. Sandholtz provides a rich and beautifully narrated analysis of how the norms and practices of art plunder have changed, from the appropriation of art serving a crucial symbolic function of asserting the cultural supremacy of the conquerors, to the wartime plunder of art becoming illegitimate and prohibited. He effectively shows that actions in the context of a number of wars—the Napoleonic Wars, the two world wars, wars of the 1990s, and the U.S. invasion of Iraq in 2003—gave rise to debates about the rules on art plunder, each of which altered the normative context for the subsequent conflict. By demonstrating how normative material from one phase reemerges, becomes modified, and is used in a later period, the analysis makes a good case against the treatment of norms change simply as discrete, actor-driven events of bargaining, persuasion, or coercion. In this book, art plunder furthermore functions as a lens through which the reader can follow the historical development of the laws of war more broadly.

International Norms is a collection of 10 case studies that deploy the cycle theory with varied success. Authored by Sandholtz, Kendall Stiles, and a number of students, the chapters cover a range of familiar norm topics (e.g., terrorism, slavery, genocide, humanitarian intervention, and democracy), as well as some less common ones (e.g., exclusive internal jurisdiction). Whereas Prohibiting Plunder puts forth modest claims about the cycle theory, arguing that “it is not the only way in which international rules evolve” (p. 23), International Norms turns the cycle theory into a forceful, generalizing proposition. However, although the aim of the collaboration is “to test that proposition in a variety of normative domains” (p. ix), no alternative explanations are provided and assessed. The model is thus deployed rather than put to the test. What is more, a number of the chapters do not actually seem to tell a norms cycle story of how action in a context of normative contradictions leads to disputes, which in turn produce rule change. For instance, the chapters on piracy and terrorism provide actor-driven analyses, in which norms disputes appear to be initiated and settled by major states. The chapter on the norm of exclusive internal jurisdiction—while in other respects the most interesting chapter of the volume—relies heavily on the shifting identities of non-Western states to explain the emergence of disputes over extraterritorial courts. The chapters thus seem to support Sandholtz's original contention that there are multiple causal processes of norms change. Rather than making a persuasive case for the general applicability of the cycle theory, the volume's main contribution lies in providing a collection of chapters that carefully trace out the development of legal instruments and some arguments surrounding 10 central international norms. As such, the book is a valuable resource for upper-level undergraduate or graduate-level courses in international law.

For all their merits—and there are clearly many—these books share a major limitation with most of the existing literature on international norms, namely, an unwavering belief in the progressive nature of liberalism. Both books advance the familiar substantive argument that “the major developments in international norms for the past two centuries are part of the broader flow of values and principles that have created, and continue to shape, a liberal world” (Sandholtz and Stiles, p. 20). They do so without investigating the influence of alternative bodies of ideas and principles. Indeed, there is such certainty about what liberalism is and what liberalism does in this literature that this substantive argument appears to be in little need of empirical examination.

It is only by avoiding uncomfortable developments and practices, however, that the authors are able to make such definitive claims. For instance, Prohibiting Plunder provides an argument about the norms against art plunder as a “liberal” set of values without discussing European colonialism and the many art treasures gathered through colonial pillage, which still remain in European and North American museums. The chapter on the norm against territorial conquest in International Norms likewise advances the liberal thesis without treating either European colonialism or the 2003 U.S. occupation of Iraq! What are we to make of these liberal practices? Were liberal states somehow still partially plagued by nonliberal norms that would account for such behaviors? Or could liberalism—as a complex set of contradictory ideas whose meanings are not fixed—in fact be compatible with these practices? Could liberal ideas even be a source of them?

Other seemingly anomalous developments are likewise left unexplored. Stiles's chapter in International Norms on the norm against slavery reports that slavery today is more common than in the eighteenth century. This is a development worth puzzling over for someone linking liberal norms to the end of slavery. And, yet, Stiles simply comments that “current slaves are ‘disposible,’ meaning that they are likely to be worked to death and then discarded without hesitation…. [T]hey are like an inexpensive machine to be used up, thrown away, and replaced” (p. 198). This reader is left wondering why these practices are not included in the broader flow of liberal values. Why should we not understand “new slavery” as linked to liberal economic practices of commodification?

These exciting books, like the scholarship on international norms more broadly, would benefit considerably from an exploration of the complexities and ambiguities of liberalism, as well as the role of other bodies of ideas and practices in the development of international norms.