Letters of the Sepulchre
The laws made by Godfrey and the Patriarchs of the court of Jerusalem. There were two codes, one respecting the privileges of the nobles, and the other respecting the rights and duties of the burghers. They were kept in a coffer laid up in the Church of the Holy Sepulchre.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894