Professor Mayer's researches into the English Cardinal Reginald Pole and into Galileo led him to investigate the structure and methods of the Inquisition, of which they are often portrayed as illustrious victims. Despite all the scholarly modern literature, ignorance and prejudice still abound and while Mayer is less than hopeful about overcoming prejudice, surely this accomplished volume will have an impact. He even concludes that, compared with many secular tribunals, the Roman Inquisition's justice stood out and played an overlooked role in the evolution of ‘human rights’; revisionism indeed.

There were medieval forms of inquisition, but the modern age saw the establishment of the Spanish (1478), Portuguese (1536) and Roman (1542) Inquisitions. It is this last, firmly papal, Inquisition that Mayer examines, in a minutely documented yet wide-ranging way, covering (broadly) the century after 1542. At its centre was a Roman Congregation, later generally known as the Holy Office, having what might be called satellite tribunals throughout much of Italy. Mayer begins with an overview of the Roman Inquisition's development after its (re)foundation, devotes three chapters to the men who worked the Roman Inquisition and finally examines the trial process and attempts to reconstruct how cases were conducted. He does not elaborate on the jurisdiction and functions of the Congregation. He pays particular attention to registers of decrees, and his original research into a mass of documentation results in a unique picture. The text consists of 215 pages; the notes and apparatus come to almost 170 pages.

Chapters 2 to 4 assemble biographies and other information on several members of the Roman Inquisition, from popes to cardinals and other key staff members; this last group included the commissaries, assessors, fiscals, notaries, summistae and consultors. Inevitably, the selection and emphases are at times directed by the focus on the Galileo case. The biographies and careers of these men contribute to explaining the nature and workings of the Roman Inquisition. Mayer estimates that the large majority of the professionals published books or left manuscript writings, including many manuals of Inquisition procedure, most of them unfinished and unpublished. This estimate could have been usefully tabulated, a technique favoured by the author, as his eight tables show. For Mayer, Urban VIII had a singularly incisive part to play in the running of the Congregation. Given that the Dominicans were so structurally involved in the Roman Inquisition, it is surprising that the author does not appear to make use of the large (658-page) publication Praedicatores, Inquisitores, volume III, edited by Carlo Longo OP and devoted precisely to Dominicans and the Roman Inquisition (Rome, 2008).

Mayer takes a positive view of just how many of the rules concerning the Inquisition's procedures can be reliably reconstructed for the period. This is despite numerous changes since the medieval origins of inquisitio, the complexity of juridical commentaries and the flexibility of practice. Nevertheless, his final chapter will be essential reading from now on. There are striking observations, some awaiting further study before they can be confirmed and possibly extended. A link to the workings of the Rota is underlined, and the points are made that extensive rules governed the use of torture, that executions were comparatively infrequent and that sentences were regularly, perhaps even usually, commuted, save for the very worst offenders. More discussion is certainly needed on the nature and exercise of papal authority in these types of proceedings, and Mayer stresses the high degree of flexibility in the Inquisition's procedures and the impact that direct papal involvement might have. More generally, further studies are needed on early modern law and lawyers, canon and civil, before a complete assessment of the Roman Inquisition can emerge. It is significant to find references to natural law in the complex literature on the consequences of adopting summary rather than plenary proceedings.

Mayer's solid scholarship confirms the view that the Roman Inquisition's procedures were sufficiently open and dynamic to grasp the reality of continual change between legislation, doctrine, jurisprudence and custom. As for the wider question of the Inquisition's ‘quality of justice’, Mayer considers that this may or may not be a historical issue, but he indicates the usefulness of comparative legal studies. The relationship of history to theology and the passing of moral judgments was central to Pope John Paul II's 1998 address to an International Symposium on the Inquisition, but that is another story.