Pope Clement VI issues the papal bull Unigenitus, laying out the scriptural justification for indulgences, identifying only the Pope and episcopate as capable of accessing the treasury of merit, and establishing a jubilee year every half century.

Pope Clement VI, born Pierre Roger, was head of the Catholic Church from 7 May 1342 to his death, in December 1352. He was the fourth Avignon pope. Clement reigned during the first visitation of the Black Death (1348–1350), during which he granted remission of sins to all who died of the plague.

A papal bull is a type of public decree, letters patent, or charter issued by the pope of the Catholic Church. It is named after the leaden seal (bulla) traditionally appended to authenticate it.

Unigenitus is a papal bull promulgated by Pope Clement VI on January 27, 1343. It designated the year 1350 as a year of Jubilee and set the tradition for a Jubilee to be held every fifty years.

In the teaching of the Catholic Church, an indulgence is "a way to reduce the amount of punishment one has to undergo for (forgiven) sins". The Catechism of the Catholic Church describes an indulgence as "a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions…"

The treasury of all merit or treasury of the Church consists, according to Catholic belief, of the merits of Jesus Christ and his faithful, a treasury that because of the communion of saints benefits others, too. According to the Westminster Dictionary of Theological Terms, this Catholic belief is a way of expressing the view that the good works done by Jesus and others can benefit other people, and "contemporary Roman Catholic theologians see it as a metaphor for ways in which the faith of Christ and the saints helps others".