Assizes of Jerusalem

Also known as Assises de Jérusalem, Letters of the Holy Sepulchre (legendary)

The body of customary law of the Kingdom of Jerusalem, surviving mostly in 13th-century treatises composed in Cyprus after the kingdom had already lost most of its territory.

The Assizes were the kingdom's customary law: a corpus of judicial decisions, baronial precedents, and feudal practice that grew up alongside the institutions of the Haute Cour and Cour des Bourgeois. Tradition held that the original assizes had been written down by Godfrey of Bouillon and his barons and deposited in the Holy Sepulchre — the so-called Letters of the Holy Sepulchre — but no such text has ever been found, and most modern historians regard the story as a 13th-century legitimating myth rather than a historical record.

What does survive is a remarkable cluster of legal treatises composed in the diaspora: John of Ibelin's monumental Livre des Assises (c. 1265), Philip of Novara's earlier Livre de forme de plait, the anonymous Livre au roi (c. 1198–1205), and the bourgeois Livre des Assises de la Cour des Bourgeois. Almost all were written in Cyprus after the kingdom had been reduced to a coastal strip, and their picture of a rigorously feudal monarchy limited by the Haute Cour partly reflects the political agenda of the 13th-century Ibelin party rather than the practice of the 12th century. Used carefully, however, they remain the single richest source for medieval feudal law anywhere in Latin Christendom.

Read more on Wikipedia: English article