In Unsafe for Democracy, William H. Thomas Jr. argues persuasively that the Justice Department played a much larger role in monitoring Americans' speech during World War I than its record under the Espionage and Sedition Acts reflects. Thomas focuses his study on the Department's investigators—federal officials across the country who, with the help of informants, attended speeches, took notes on religious sermons, and eavesdropped in restaurants to gather information on Americans who opposed the war. Drawing extensively on the files of the Justice Department's Bureau of Investigation, Thomas provides a wealth of colorful examples as he describes the Department's surveillance. Incriminating evidence—such as failing to purchase war bonds or keeping a portrait of the Kaiser in one's home—often fell short of what was needed for prosecution. In such cases, investigators met privately with those who had expressed doubts about the war effort, urging them in some cases to keep their doubts to themselves, and in others to redouble their expressions of loyalty. Failing to do so would result, investigators warned, in more serious legal action. While investigators acted under color of law, they lacked the legal authority to demand Americans' silence. Their interactions with Americans—in particular the radicals, labor officials, and religious leaders singled out for investigation—nonetheless achieved the Justice Department's goals, helping to weaken the Socialist Party and the IWW and encouraging many to avoid any speech that might be considered unpatriotic. Implicit in this story is the idea that the difference between federal action and private coercion was less clear than historians have thought.

Thomas organizes his narrative thematically, first offering a broad overview of the Justice Department's practices and then detailing in individual chapters the Department's contacts with ministers, members of left-leaning groups, and vigilantes across the nation. In the book's strongest chapter, “Policing Wisconsin,” Thomas broadens his inquiry and examines how Justice Department investigators joined with local law enforcement agents, educators, newspaper editors, and postal employees to ensure that Wisconsin residents supported the war. Investigators actively inserted themselves into religious disputes, labor strikes, and Socialist Party activities, often in league with informants seeking their own political advantage. By moving beyond an otherwise tight focus on investigators' contacts with suspicious individuals, Thomas is able to demonstrate how the complexity of local politics influenced Justice Department investigators' own efforts.

Thomas locates the Justice Department's activities in the broader context of Progressive reform, suggesting that the Department's personnel, organization, and ethos reflected the Progressives' commitment to bureaucracy and expertise. Here as elsewhere, Thomas suggests, these administrative tools were used for questionable goals. Indeed, the purposeful development of administrative capacities to limit speech indicates a key point about the bureaucratic process. As a number of scholars have demonstrated, Americans had long been concerned with administrative officials' discretionary authority, and Thomas's portrayal of Justice Department investigators illustrates why. These officials brought their own assumptions about appropriate behavior to bear as they defined subversion, with little scrutiny from their superiors or the courts. While some investigators downplayed the risk certain speakers posed (and on occasion intervened to discourage vigilantes from taking more forceful action against them), others were particularly suspicious of immigrants, African Americans, women, Germans, and leftists.

Unsafe for Democracy describes a staggering degree of government intervention into individuals' lives. The book's strength is in its detailed descriptions of these interactions; at times, however, Thomas overwhelms the reader with numerous and often lengthy quotes. In addition, by focusing so closely on investigators' activities, Thomas misses the opportunity to reflect on their broader significance. Thomas's research does, however, suggest intriguing possibilities for future analysis. First, given how federal officials (with the help of the American Protective League) blurred the line between legal and extralegal action, Thomas's study demonstrates that a broader reevaluation of the Justice Department's wartime legacy is in order. As the author briefly mentions, the surveillance programs developed by the Bureau of Investigation—later the Federal Bureau of Investigation—in the decades following World War I can be traced back to the wartime activities described here. In addition, scholars interested in the World War I home front may want to consider how the Justice Department's undercover investigators engaged with communities to help Americans police the loyalty of their friends and neighbors. Finally, scholars of the Progressive era might fruitfully explore what these findings about the Justice Department's informal methods add to our growing understanding of administrative capacities in this period. Overall, by pushing beyond the Justice Department's courtroom record, Unsafe for Democracy is a significant contribution to our understanding of the repressive culture of the war years.