That which was published in 1584 was drawn up by Juan de Mariana, who soon after had some of his own works prohibited. In 1611, a new index was formed under the inquisitor-general Don Bernard de Roxas de Sandoval.

The Cardinal Zapata, who succeeded Roxas, adopted one more extended in 1620, and it was used by his successor, Don Antonio de Sotomayer, in 1630. This catalogue was the first which the inquisitors presumed to publish from their own authority, and without being commissioned by government. Don Diego Sarmiento Valladares, inquisitor-general, in 1681, began to reprint it with additions, and it was finished by Don Vidal Marin, who published it in 1707.

Don Francis Perez del Prado, another inquisitor-general, commissioned the Jesuits Casani and Carrasco to compose a new catalogue. Although these monks were not authorized by the Supreme Council, they inserted in the list all the books which they supposed to be favourable to the Jansenists, Baius and Father Quesnel. Their conduct was denounced to the Supreme Council by the Dominican Concina, and some other monks; the Jesuits were examined, and defended themselves: the council, though it could not approve, did not carry the affair further; it had not sufficient power to balance the influence of the Jesuit Francis Rabago, who was confessor to Ferdinand VI.

Among the books which they prohibited were the works of Cardinal Norris, which were held in general estimation by the learned throughout Christendom. Benedict XIV., in 1748, addressed a brief to the inquisitor-general, commanding him to revoke the prohibition; as this order was not obeyed, the Pope complained to the king, but was unable to obtain his request until ten years after, when the Jesuit Rabago no longer directed the conscience of the monarch.

The index of the Jesuits also contained several treatises of the venerable Don Juan de Palafox y Mendoza, Archbishop and Viceroy of Mexico. The congregation of rites afterwards declared that there was nothing in them worthy of censure, and the inquisitor-general was obliged to revoke the prohibition in an edict, the copies of which were immediately bought up by some friends of the Jesuits. To give an idea of the criticism of Perez del Prado, it is sufficient to say that he bitterly lamented the misfortunes of the age he lived in, saying, "That some individuals had carried their audacity to the execrable extremity of demanding permission to read the Holy Scriptures in the vulgar tongue, without fearing to encounter mortal poison therein."

In 1792 a new index was published, without the consent, and even in opposition to the Supreme Council, by Don Augustine Rubin de Cevallos, inquisitor-general. It is this index which is still in force, but the prohibitions and expurgatory measures have since been multiplied.

The prohibitory decrees are preceded by qualification. The process is instituted before the supreme council; but as the information is generally laid before the inquisitors of the court, they appoint the qualifiers who censure the book. A copy of the work and the denunciation is sent to the first qualifier, and afterwards to the second, unsigned by the opinion of the first; if they do not accord, copies are sent a third time before it is submitted to the Supreme Council. The inquisitors of the provinces have likewise the privilege of receiving informations: they proceed in the same manner; but the council always commission the inquisitors of the court to censure books, because they were more sure of their qualifiers.

If any person presumed to buy, keep, or read prohibited books, he rendered himself liable to be suspected of heresy by the inquisitors, although it might not be proved that he became an heretic from such reading; he incurred the punishment of major excommunication, and was proceeded against by the tribunal: the result of this action was the absolution ad cautelam.

During the last years of the eighteenth century, no person has been imprisoned for reading prohibited books, unless he was convicted of having advanced or written heretical propositions. The punishment inflicted was merely a pecuniary penalty, and a declaration that the individual was slightly suspected of heresy; it must be acknowledged that this qualification was omitted, if there was any reason to suppose that the accused had erred from motives of curiosity, and not from a tendency to false doctrine. Nevertheless all these proceedings are arbitrary, and the inquisitors have the power of pursuing the infringers of this law as if they were heretics.

The permission to read prohibited books, rendered all actions instituted against those who violated the law ineffectual. The Pope granted it for a sum of money, without inquiring if the person who demanded it was capable of abusing the permission. The inquisitor-general of Spain acted with more prudence; he took secret informations on the conduct of the solicitor, and required him to state in writing the object of his demand, and the subject on which he wished to consult the prohibited books. Where the permission granted was general, the books mentioned in the edicts were excepted. In this sense the works of Rousseau, Montesquieu, Mirabeau, Diderot, d'Alembert, Voltaire, and several other modern philosophers, among whom was Filangieri, were excepted from the privilege. During the last years of the Inquisition, the permissions granted by the Court of Rome did not defend the persons who received them from the inquisitorial actions; they were subject to revision, and the inquisitor-general did not authorize the use of them without great difficulty, and as if the Court of Rome had never granted them.