The Peace Preservation Law of 1925 is perhaps the Imperial Diet's most infamous piece of legislation. Drafted to curb communist and anti-colonial nationalist activism, it outlawed conspiracies to alter the “kokutai” (commonly translated as “national polity” or “essence”) and the system of private property. Progressive critics called it an “evil law” (akuhō) at the time of its passage, while more recently it has served as a cautionary tale for critics of Prime Minister Abe Shinzō’s Anti-Conspiracy Bill. Both in its wide-ranging effects and in its notoriety, the law had a profound impact on political discourse under imperial Japan and how commentators today discuss civil liberties. Befitting that important role, the Peace Preservation Law has been the topic of many books over the years. Max Ward's new book, Thought Crime: Ideology and State Power in Interwar Japan, significantly moves the discussion forward, offering a powerful interpretation of the law and its history that has important consequences for understanding the imperial ideology of the era and the relationship between ideology and state power more broadly.

Thought Crime is organized according to themes regarding state power that Ward sees as key to understanding the ideological import of the Peace Preservation Law, which largely coincide with the chronological development of the law's application. Thus, the book traces the trajectory of the law from its inception as legislation designed to repress forms of thought deemed by the authorities to be a threat, to a broader system for rehabilitating thought criminals and converting them into model imperial subjects who police themselves. At the core of Ward's analysis is the metaphor of “ghost in the machine,” a concept he borrows from Gilbert Ryle. Ward argues that imperial ideology and its corollary, imperial subjecthood, are ghostly in nature; they have no essence or material basis, but as oft-invoked ideas assumed to have such essence, they generate practical effects that animate the “machine” of state power.

As Ward demonstrates in chapter 1, the Peace Preservation Law serves as a useful lens through which to study imperial ideology in the realm of law because it is there that kokutai is first introduced as a legal concept. By introducing this concept denoting imperial sovereignty into a law designed to identify and police seditious behavior, lawmakers and government officials inadvertently established a trajectory wherein future interpretation and execution of the law would entail defining (or attempting to define) what constituted imperial sovereignty and its relation to imperial subjects.

As arrests under the new law multiplied, officials in the Justice Ministry sought to develop methods for rehabilitating thought criminals (chapter 2) into faithful “imperial subjects,” a category that was inevitably defined in tandem with the kokutai ideology due to the legal framework established by the Peace Preservation Law. As the application of the law expanded in new and unexpected ways, Ward notes that “state officials’ own understanding of the imperial kokutai was changing, indicating how the imperial sovereign remained an elusive ghost even as it animated this expanding and changing justice apparatus” (p. 67). In building this narrative arc of institutional changes, Ward takes inspiration from Foucault in showing how bureaucrats developed techniques designed to repress, rehabilitate, and foster self-policing. According to Ward, the Peace Preservation Law apparatus, the kokutai ideology, and the phenomenon of ideological conversion (tenkō) are best understood as examples of modes of power that are observable in modern states in general, and not something particular to Japan, as historians have tended to argue in the past.

Ward, following Althusser, describes the relationship between state and ideology as being much more than government agencies imparting nationalist ideas to the masses. The Peace Preservation Law required a broad array of semi-official organizations and individuals in building its apparatus for ideological conversion. This is where Ward's meticulous research shines the most, as he explores how religious institutions and chaplains, family members, community groups and leaders, and other entities mobilized themselves in creating a system for producing converts who would act in the world as model imperial subjects, a topic discussed at length in chapter 3. Along the way, we are introduced to key individuals such as Hirata Isao, the Justice Ministry official who was the key architect of the Peace Preservation Law apparatus, and Kobayashi Morito, a former communist-turned-thought guidance counselor who was the archetypical model of a political criminal who narrated his journey towards recovering his Japaneseness for others to follow.

In chapters 4 and 5, Ward describes how these institutional practices became an ideology in itself, what he refers to as an “ideology of conversion,” which “elevat(ed) the image of the reformed thought criminal as the model of the imperial subject for all to follow” (pp. 147–48). By the late 1930s, officials like Hirata were urging all to commit tenkō in mobilizing for an ideological war on a global scale.

Thought Crime sets itself apart from past studies of the Peace Preservation Law by developing a theory of imperial ideology that focuses on its effects on those in proximity to it: bureaucrats, thought criminals, and those who were mobilized to rehabilitate them. In focusing on the effects, Ward is able to avoid the pitfall of attempting to define “kokutai” himself or asking the impossible question of whether converts had indeed converted. The book will be essential reading for those interested in state power and ideology in imperial Japan, as well as a broader readership seeking to understand the history of anti-radical laws and government approaches to defining and dealing with political threats. As Ward observes in his preface, the legal questions and ideological issues explored in recent court cases involving US citizens involved in ISIL have been remarkably similar to those of the Peace Preservation Law. As the best historical writings often are, Thought Crime is well grounded in both a broad range of historical sources from the past and the contemporary situation that we inhabit today.