In her book, Excommunication and Outlawry in the Legal World of Medieveal Iceland, Elizabeth Walgenbach explores the medieval juridical terms outlawry and excommunication as they appear in source material from medieval Iceland—and most importantly, manuscript sources dating to the thirteenth and fourteenth centuries. Central to the volume is the question as to the relationship between these two sanctions, which, as historians of medieval Europe have regularly noted, share many features—for example, in terms of implementation and consequences in this world and the other. One way to account for these similarities has been to frame excommunication as an add-on to the pre-Christian legal world where outlawry was already an established punishment. This view is frequently summarized through Frederic W. Maitland's well-known description of excommunication as ecclesiastical outlawry and in the more restricted scholarly context of medieval Iceland, it has been kept aloft in the work of scholars like Lára Magnúsardóttir. Walgenbach's thesis goes contrary to such models of explanation. Influenced by developments in the field of medieval Icelandic culture and society ushered in by the “new philology,” she argues that the source material that had previously been taken to contain information about outlawry as a pre-Christian sanction—importantly the law collection Grágás and a group of family sagas sometimes called the “outlaw sagas”—should not be read in the context of the period these texts purport to describe but as part of the historical period in which the manuscripts emerged, namely the thirteenth and fourteenth centuries. On such premises, Walgenbach argues that excommunication and outlawry belong to the same legal culture, shaped by the Church and canon law, and further recommends explaining their similarities in that light, explaining outlawry as strongly influenced by excommuncation, namely as “a type of excommunication” (97).

The book is divided into five enumerated chapters, accompanied by a short introduction and conclusion. In the first two chapters, in a series of short (sometimes too short) subchapters, the author helpfully provides necessary background information, tracing the history of the two terms (excommunication and outlawry) respectively with a special focus on their representation in medieval Icelandic sources. In the first chapter, Walgenbach discusses a series of milestones in the history of excommunication in the Middle Ages and developments in canon law, such as the introduction of a distinction between major and minor excommunication as well as between communication ferendae sententiae and latae sententiae, all of which found its way to Iceland in the Middle Ages, albeit a bit later than elsewhere. In a similar survey in the second chapter, Walgenbach goes through the history of outlawry, assessing the Icelandic source material, legal sources such as Grágás, and narrative sources such as family sagas and contemporary sagas. She emphasizes the lack of consistency in how the sanction of outlawry is presented in the sources, especially the subtype of lesser outlawry (fjǫrbaugsgarðr) and warns against reading passages from medieval Icelandic law codes as reflecting actual historical practices.

The core of Walgenbach's argumentation is laid out in the book's third chapter, “Outlawry as Secular Excommunication,” where she engages critically with previous scholarship on the topic and sets out her methodological premises. In the chapter, she explores in detail the similarities between outlawry and excommunication, making her case for understanding them as part of the same legal world where two legal systems, the ecclesiastical one and the local, “secular” one, overlapped and cooperated. This chapter is highly intriguing but would certainly benefit from a clearer structure. Generally speaking, the main flaw of Walgenbach's book is on the level of content organization, where more efforts would have been needed to make the text more accessible, as well as the formalities, where too many errors might irritate the reader and draw the attention from the content.

In chapters 4 and 5, the author puts her argument to the test by analyzing two cases from medieval Iceland in which outlawry and excommunication play a role. Up for inspection in the fourth chapter is Sturla Þórðarson's Íslendinga saga, focusing on the conflict between bishop Guðmundr Arason and Kolbeinn Tumason. Walgenbach highlights how outlawry and excommunication appear similar in terms of implementation and repercussion, stating that “Sturla presents a view of the two sanctions that leaves little distinction between them except that a bishop excommunicates, while a chieftain outlaws” (125). Further illustrating how the two sanctions should be understood as shaped by and a part of Christian culture, Walgenbach insists on the intertextual relationship between Sturlunga's account of the altercation between bishop Guðmundr and the Old Norse-Icelandic version of the life of Thomas Becket, Thómas saga, in which, according to Walgenbach, the two sanctions appear just as similar as in Íslendinga saga. In the fifth and final chapter, Walgenbach discusses accounts of Aron Hjǫrleifsson, an outlaw-hero of the thirteenth century, an enemy of the Sturlungs, and a supporter of bishop Guðmundr. In medieval accounts about Aron (most importantly Arons saga but also Íslendinga saga and Guðmundar saga A), she highlights the Christian religious elements in the representation of outlawry, it being described as damnation in hell and ultimately redeemable through atonement and pilgrimage.

Walgenbach's thesis is original. On solid methodological grounds, she proposes to move the question as to the relationship between the two sanctions forward in time to a period when the Roman Church was well on its way to establishing itself as the most powerful institution in society. With regard to the question of how the sanction of outlawry may have manifested itself in a pre-Christian society, it is simply out of reach for the historian, Walgenbach insists in view of the dating of the relevant manuscripts. This is a somewhat frustrating conclusion, granted that outlawry existed as a sanction before the Roman Church rose to its position of cultural hegemony, a fact regularly brought up in the book, and there are certainly ways to approach the matter from a sound historical point of view, although Walgenbach's approach does not allow for it. In the broader context of the scholarly field of the Christian religion in medieval Iceland, Walgenbach's book is a welcome contribution to a growing historiographical tradition, reacting to the long-standing underestimation of the influence of the Christian religion in medieval Iceland. Her book contains fresh insights and novel readings supporting the view of Christianity as a shaping force in medieval Icelandic culture. The Christianization of outlawry is a central but far from the only example thereof found in Walgenbach's Excommunication and Outlawry in the Legal World of Medieval Iceland.