From a sym­bolic and cul­tural per­spective, issuing a new leg­is­lation was cer­tainly one of the most sig­nif­icant expres­sions of the strength of the new political power. The com­bi­nation of the paci­fi­cation of the kingdom, achieved by the king right after his coro­nation and imple­mented through a mil­itary crackdown, with a new pro­duction of norms that were intended pri­marily to maintain a peace con­quered by blood, is a topos of the medieval monar­chies. Roger pro­mul­gater his leg­is­lation, the so-called Assisae de Ariano (the con­ven­tional date is 1140, but there are doubts). The preface of the work is fun­da­mental for under­standing the role of this leg­is­lation.  It stated that these laws were offered to God in return for having given the kingdom to Roger.

The Norman King declares as its task the enactment of new leg­is­lation, which is a function of its power of juris­diction. The nor­mative order con­sists of a plu­rality of sources that Roger for­mally main­tains in force, but that are hier­ar­chi­cally sub­mitted to the royal legislation.

In 1231, Fred­erick II, who was also the Emperor of the Holy Empire, pro­mul­gated his com­pi­lation of laws as king of Sicily. The preface directly links the new leg­is­lation to cos­mogony. In the political expe­rience of the Kingdom of Sicily, new leg­is­lation is the man­i­fes­tation of royal power, but at the same time sets its limits.

The first con­se­quence was the Pope’s strong reaction. Gregory IX excom­mu­ni­cated Fred­erick II for many reasons, but the main one was his ide­ology of con­sti­tu­tional power. The Pope — vicar of Christ on the hearth — deeply believed that he was the only one to have the power to make law; as con­se­quence Fred­erick was a usurper of his juris­diction. He was the beast of the Apocalypse!

A few years after, in 1234, Gregory IX pro­mul­gated his code, the so-called Liber Extra, as an answer to the erethic king-emperor.

This seminar aims at showing how the dif­ferent kinds of leg­is­lation are con­nected one to one :  royal leg­is­lation, papal dec­retals, but also cus­tomary law —  both local customs and ethnic customs – Arabic, Greek, and Latin, only for quoting the most important.