† In 1908 The Sacred Congregation of the Universal Inquisition had a public relations problem. The Roman Inquisition had become associated with everything bad about the Roman Catholic Church, largely due to the infamous trials held during the Renaissance. So Pope Pius X officially renamed it the Sacred Congregation of the Holy Office. It was still largely the same institution, but it was changing as the power of the Church continued its slow decline.
† The power of the Holy Office has waxed and waned in response to two factors. The ability of the church enforce its decisions and the perceived necessity to fight against heresy. By the time it was renamed the Congregation for the Doctrine of the Faith in 1965 all persecution of Catholics not part of the hierarchy of the Church had quietly ceased because being part of the Catholic Church was no longer perceived as critical to salvation. Excommunication no longer held the same terror that it once did and there was no temporal power to arrest believers for the previous eighty years.
† Its origins are with the first Roman Inquisition founded by Pope Innocent III in the 13th century to examine the Albigenses and other heretics of the south of France. In AD 1542 by Pope Paul III declared it the supreme tribunal for the whole of the world. The era of real power for the Inquisition had begun.
† In AD 1558 it was made a congregation, a part of the Roman Curia with the official name Romanæ Universalis Inquisitionis Congregatio. Though headed by cardinals much of the upper administration of all the congregations was dominated by members of the Dominican Order. During its heyday it was the primary body for not only deciding the official doctrine of the church (with the approval of the Pope), but also to decide if anyone had violated this. It retained these two functions right through the 20th century, though in a much reduced fashion. It was given power over every person on earth, except for cardinals. It had the power to decide if a person would be declared a saint and the nomination of bishops. It even had the power, to give dispensation from abstinence, from fasting,, from the observance of feasts, and vows made in religious institutions. Related was the Congregation of the Index, the official body that decided if a book was contrary or injurious to Catholic morals and published the Index librorum prohibitorum (Index of Prohibited Books) until AD 1966. It was in fact, though not officially, an auxiliary to the Holy Office and also dominated by the Dominican Order for much of its history.
† During the Catholic Reformation many trials were held in response to the threats presented by protestants and scientists. Most infamous of these was the trail of Galileo Galilei for supporting Copernican theory, at the time widely believed to be both false and anti-scriptural. (Among others Martin Luther strongly condemned Copernicus.) This became a public relations disaster for the Church in later centuries and was part of the reason for the eventual name change of the congregation. Also rather infamous was the use of torture or the threat of torture used in trials of the time (though in fairness it should be noted that civil trials used torture quite often as well.) and the burning at the stake of some heretics for diabolism.
† With the rise of secular states the power of the Holy Office started to fade. It could no longer directly forbid publication of books and lost the power to subject people to arrest outside the Papal States. Instead it could only make things difficult for people in states where reverence for the church was such that they would carry out many orders of the Holy Office. Frequently the banning of books was in response to them being placed on the Index right up through the early 20th century. There have been no trials of lay Catholics since its renaming in 1908.