This is a collection of canon laws that was issued by and attributed to Pope Gregory IX in 1230, although the actual drafting of the text had been done by his chaplain: the Dominican friar Raymond of Penyafort (c.1175-1275). This printed edition includes a gloss by the 13th-century jurist Bernardo of Parma, which supported the understanding of the Decretals by clarifying specialist legal language and by guiding the reader in their evaluation of the text’s meaning. The purpose of the Decretals was to regulate and uniform legislation for Rome as well as local churches, and the great survival of manuscripts suggests its popularity: as the universities of Bologna and Padua established seats for teaching law, so increased the need for textbooks. While this text was considered a legal authority in the Middle Ages, the humanists and later also the Protestants did not hold it in such high regard, lamenting its connection to the corrupted, power-grabbing institution of the Catholic Church.

This edition was printed by Peter Schoeffer, son-in-law and successor to Gutenberg in Mainz. The copy in the Royal Library is unusually printed on both paper and vellum, and includes some illumination. It is important to stress that the presence of lavish decoration does not automatically imply that the book had more of an aesthetic purpose than a practical one: the first decorated law books date from the late 12th century, and within 100 years they had an established iconography. Furthermore, the presence of the gloss alone suggests that the volume was intended to be studied and consulted, despite the absence of reader use evidence such as handwritten marginalia in this copy.

Binding description
Alum tawed pigskin covers, decorated with blind fillets to form concentric borders with blind tools at the corners and lozenges in the middle. Spine with five false raised bands, sewn on four cords with a double headband that was hand-sewn in silk (green, white and orange). Finishing done by Richard Day (c.1957-2002); modern sewn-in structure from the 1960s.