The Ashgate Research Companion to Islamic Law is a collection of essays that attempt to give a comprehensive overview of modern scholarship on the historical development of Islamic law, its substantive content, and its encounter with the modern nation-state. It is divided into an introduction and four parts: the first exploring the origins, sources, and participants of Islamic jurisprudence; the second on substantive legal issues such as equality, gender, and political order; the third examining the modern state, legislative powers, colonialism, and Islamization; and the last discussing current discourse about Islamic finance, ethics, and the state of shariʿa today. An epilogue by Abdullahi An-Naʿim tackles the normative question of the future of the shariʿa in secular political orders within Muslim majority countries.

A major theme of these essays is the suggestion that Islamic law should be regarded as a private normativity, genuinely religious in its origin and its function, rather than the kind of law that could be implemented by a state today, or that could have been derived from governmental practices to begin with. For instance, in his overview of scholarship on the origins of Islamic law Knut Vikør discredits the revisionist theories put forward by Ignaz Goldziher and Joseph Schacht, who saw the law's roots in local and administrative practices rather than the Prophetic message, in favor of the views of Harald Motzki and Wael Hallaq, who downplay non-Islamic influences and emphasize the law's originality and its distinctly prophetic character. Similarly Herbert Berg, in his chapter on the origins of the Qurʾan and sunna, favors the anti-revisionist views of Harald Motzki and Behnam Sadeghi, who use historical methods to support relatively traditional views. Hallaq's influence appears again in Paul Powers’ overview of scholarship on the history of the schools of law: he accepts Hallaq's refutation of Schacht's idea that they began as regional schools, while suggesting that Christopher Melchert's account of the madhhab's educational and transmission of knowledge components, while based on Schacht's thesis, is not incompatible with Hallaq's more doctrinally focused account.

In the section on substantive legal issues, Andrew March notes that in early Islam political authority was based on charismatic and contractual foundations, but that elements of a theory of constitutional authority did eventually emerge in Islamic legal, theological, and political writing. In the section on the law's relation to the modern state, however, Léon Buskens argues that the idea of Islamic law as state law is an invention of the colonial legal regimes that transformed Islamic normativity and stripped it of its plurality, its tolerance of local customs, and its ability to respond to social transformations. Maurits Berger continues this theme, arguing that “[t]he authority of Sharia itself has evolved from a source of normativity in the private domain into a source of codification and then into a driving force of morality in the public domain” (223). The nation state, he says, reduced the shariʿa to an oppressive and restrictive system, and left the class of legal professionals vulnerable to fundamentalist ideas. In the section on the current state of shariʿa, Mathias Rohe warns that if Islamic legal norms are allowed to function as parallel legal systems in countries where Muslims are minorities, they will inevitably conflict with secular legal orders over issues like gender bias.

The view that Islamic law is a private normativity rather than state law is recapped fittingly in the epilogue by Abdullahi An-Na'im, who argues that the idea of an Islamic state to enforce shariʿa norms is conceptually incoherent, historically unprecedented, and practically unworkable. Like most of the authors in this volume, he is convinced that shariʿa norms and state law are two fundamentally different normative systems, one religious and the other political. This volume provides a valuable overview and synthesis of debates within the study of Islamic law, but it leaves the impression that a consensus has settled over the field. This impression is misleading, as not all scholars and historians of Islamic law agree that the shariʿa was brought into the public domain only through colonialism and the formation of nation states, and that it essentially is, always has been, and always should remain a strictly private normativity. The views of Baber Johansen, Intisar Rabb, or Ahmad Atif Ahmad could have supplemented and nuanced the overall approach represented in this volume.