The Inquisition refers to a set of judicial procedures and tribunals established by the Catholic Church from the Middle Ages onward to investigate and judge people suspected of heresy, that is, of professing beliefs considered contrary to its official doctrine. These tribunals were ecclesiastical institutions, operating under the authority of bishops or the pope, but some, particularly in Spain and Portugal, were closely controlled by the monarchies. Their history spans several centuries and primarily concerns Europe, but also certain colonized territories. There was, however, no single Inquisition organized in the same way everywhere and at all times.
The word comes from the Latin inquisitio, meaning “inquiry” or “investigation.” It originally referred to a judicial procedure in which a judge could initiate investigations independently, without necessarily waiting for a formal accusation from a complainant. This procedure, developed in medieval law, was not used exclusively in religious matters.
The emergence of the Inquisition took place in a Europe where religious and political authorities generally regarded unity of faith as a condition of social order. Heresy was therefore perceived not merely as a doctrinal error, but also as a potential threat to the community and its institutions.
The first organized forms of the Inquisition appeared in the late 12th century. In 1184, Pope Lucius III instructed bishops to investigate movements considered heretical within their dioceses. In the 13th century, under the pontificate of Gregory IX, inquisitors specially appointed by the pope were entrusted with conducting these investigations. Many belonged to the Dominican and Franciscan orders.
This medieval Inquisition operated particularly against the Cathars and Waldensians, two religious movements whose teachings or practices were condemned by the Church. It was especially active in certain regions of southern France and Italy. Historians John H. Arnold and Peter Biller have studied these developments using documents from 13th-century French inquisitorial tribunals.
Proceedings could begin with denunciations, witness statements, or investigations conducted by inquisitors. Those being prosecuted were questioned about their beliefs and practices. Opportunities for defense varied according to the period and tribunal, but were often limited, particularly because of the secrecy surrounding certain testimonies.
Penalties varied and included religious penances, compulsory pilgrimages, the wearing of distinctive signs, imprisonment, and confiscation of property. In 1252, Pope Innocent IV authorized the use of torture under certain conditions in inquisitorial proceedings. Those condemned as obstinate or repeat heretics could be handed over to the civil authorities, who carried out their execution, sometimes by burning at the stake.
The Spanish Inquisition, established in 1478 with the authorization of Pope Sixtus IV, at the request of Ferdinand of Aragon and Isabella of Castile, was an institution distinct from the medieval Inquisition. Operating under strong royal authority, it initially prosecuted Christians of Jewish origin, known as conversos, who were suspected of continuing to practice Judaism after their conversion. It subsequently targeted other groups, including Muslims who had converted to Christianity, known as Moriscos, as well as Protestants and various forms of religious dissent.
Its activities also extended to Spain’s colonial possessions in the Americas. Historian Kimberly Lynn, in her book Between Court and Confessional: The Politics of Spanish Inquisitors, emphasizes the importance of the relationships between inquisitorial tribunals, royal power, and the administration of the empire. The Spanish Inquisition was definitively abolished in 1834.
Portugal established its own Inquisition in 1536, with the authorization of Pope Paul III. It particularly prosecuted “New Christians” of Jewish origin and also exercised authority in several territories of the Portuguese Empire. It was abolished in 1821.
In Rome, another institution was established in 1542 by Pope Paul III: the Supreme Sacred Congregation of the Roman and Universal Inquisition, which would later become the Holy Office. It dealt particularly with questions of doctrine, religious censorship, and the suppression of teachings considered heretical. Galileo was tried before this institution in 1633 for defending the movement of the Earth around the Sun. Convicted and forced to recant, he spent the remainder of his life under house arrest.
The Inquisition is also associated with autos-da-fé, public ceremonies during which sentences were proclaimed and religious penances performed. Contrary to some popular representations, an auto-da-fé was not the same as the execution of condemned individuals, which could take place separately.
The human toll of the Inquisition has been the subject of extensive historical research. Archival records show that the practices and severity of the tribunals varied considerably depending on the place and period. Overall estimates of the number of victims remain difficult to establish, particularly because of gaps in the documentary evidence and differences between the institutions studied. Historians therefore distinguish established facts from exaggerated figures that have sometimes circulated in religious and political controversies.
The Catholic Church gradually abandoned these forms of religious justice. In 1965, the Roman Holy Office became the Congregation for the Doctrine of the Faith, now known as the Dicastery for the Doctrine of the Faith. This body retains doctrinal and disciplinary responsibilities but no longer operates like the historical inquisitorial tribunals.
In 2000, Pope John Paul II asked forgiveness for acts of intolerance and violence committed in the name of defending religious truth. In a letter published in 2004, he also emphasized the need to study the history of the Inquisition rigorously, acknowledging the facts without resorting to oversimplification.