Numerous studies and research projects on the Roman Inquisition have been undertaken since 1998, the year that the Archive of the Congregation for the Doctrine of the Faith (ACDF) was opened. The best known examples include the Dizionario storico dell'Inquisizione (DSI) edited by Adriano Prosperi, the project entitled Römische Inquisition und Indexkongregation,1542–1966 under the leadership of Hubert Wolf, Christopher F. Black's excellent study The Italian Inquisition and a new edition of the publication detailing the experience of Cardinal Giovanni Morone at the hands of the Roman Inquisition written by Massimo Firpo. These are very precise studies and research projects based on the best available sources located in the ACDF. However the majority of these works give little attention to an unusual source in the archive of the Roman Inquisition, namely the series of documents called Decreta sancti officii. These documents are the minutes of the meetings of the cardinals of the Congregation of the Holy Office. These meetings were held on Wednesdays (feria IV) and Thursdays (feria V), the latter usually in the presence of the pope. The documents are an excellent summary of the daily activity of the Congregation and its members. Often the minutes drafted by the notary consisted of just a few lines but they record the cases which reached Rome from throughout the Christian world. They also inform us of the decisions taken by the cardinals and the pope in regard to these matters, as well as providing a list of the attendees and therefore also the absentees. The lack of attention given to these documents by academics is somewhat perplexing given that historical analysis is incomplete without them. For example, from the 1950s onwards the story of the Roman Inquisition has always been linked to specific case studies such as the trials of Giovanni Morone, Pietro Carnesecchi (‘the Carnesecchi Moment’ is the fifth chapter in Christopher Black's The Italian Inquisition), Giordano Bruno and Galileo. These are undoubtedly the most important cases which bear witness to the most repressive era of this institution. However complete understanding of the modus operandi of the Roman Inquisition can only be obtained by consulting all the available sources. An examination of just the trials rather than all the documents associated with them, such as the Decreta sancti officii, is misleading.

Thomas F. Mayer has broken free of the standard methodological approach to undertake new research based on an innovative assessment of the sources available. His study examines the years 1590–1640, that is to say the age of Galileo. The research is a good example of the potential of rigorous study of the Decreta sancti officii. The author does not overlook the trials, most notably that of Galileo, but he concentrates on more recent and in-depth work such as that of Francesco Beretta. The appendix (pp. 217–21) is a perfect example of the new method of study. For example, table 2 (p. 218) shows the rate of attendance of cardinals at the meetings of the Congregation, with Giovanni Garcia Millini having a 75 per cent attendance record on Wednesdays and a 84 per cent record on Thursdays. These statistics represent an important historical record and are the same as those recorded by Miguel Gotor in the entry for Cardinal Millini in the Dizionario storico dell'Inquisizione. This shows the close relationship between Millini and the Congregation of the Holy Office (DSI ii.1045). Mayer's research provides extensive biographical analysis of the cardinals and other staff making up the Congregation of the Holy Office between the papacies of Paul v and Urban viii (chs ii–iii). He also gives us detailed explanations of the roles of the various members of the Congregation, such as the positions of Cardinal Secretary, Commissary General for theological questions and the Assessor for judicial aspects (chs i, iv) and how these people interacted with the cardinals and pope. The author also describes the transformation of the Roman Inquisition from its re-foundation in 1542 under Paul iii to the reform of the Curia implemented by Sixtus v in 1588. Mayer outlines the process of stabilisation and bureaucratisation of the Holy Office at the end of the sixteenth century. This analysis can be found in chapter v which is dedicated to the procedures of the Roman Inquisition. This is probably the most original aspect of the research, in that Mayer demonstrates how the process of bureaucratisation of the Holy Office at the end of the 1500s was not followed by the enactment of more repressive laws. The late sixteenth and early seventeenth century saw a boom in the writing of judicial literature, for example manuals for inquisitors such as Francisco Peña's updating (from 1571) of Nicolau Eymerich's long-standing Directorium inquisitorum (originally written in 1368), and Sacro Arsenale by Eliseo Masini (1621). Yet it was also a time when popes often intervened personally at meetings of the Congregation to provide interpretations which often resulted in existing laws being replaced by new ones. It was no coincidence that the decisions taken at Congregation meetings which resulted in judicial reform were recorded in large volumes and sent to inquisitors located outside Rome. In most cases papal intervention was designed to correct the procedural errors of local inquisitors. However it also served to provide more equitable justice for the accused. Mayer also argues that the Roman Inquisition, when compared with contemporaneous secular courts, was a far more advanced system of justice. The author even asserts that the Roman Inquisition ‘played a role in the evolution of “human rights” that has been completely overlooked’ (p. 207). Perhaps Mayer overstates the case but, on the other hand, the Roman Inquisition is often talked about as a tribunal to judge crimes of opinion which are a very modern concept. Regardless of the welcome discussions that will result from the author's stance, the merit of this study is its innovative methodology. In this sense Thomas F. Mayer has shown the importance of studying the previously overlooked Decreta sancti officii.