Bowen explains the Latin (ius primae usufructus) translates literally as right of first use and enjoyment. "My Latin dictionary tells me that 'usus et fructus,' 'ususfructusque,' and 'ususfructus' were all forms of a legal technical term with this meaning. It survives in English as 'usufruct' which I suppose is rarely used outside legal documents, although I remember seeing it in one of William Faulkner's long sentences. John based this on the phrase ius primae noctis: 'right of the first night,' which was the feudal custom that gave the lord the right to take the virginity of his vassal's bride. I have no idea how widespread such a custom may have been - probably, like the chastity belt, its universality has been wildly exaggerated because people like scandalous stories about the middle ages, when people were all ignorant and stupid, and did these weird things all the time. Anyway I'm pretty sure that John wasn't quoting an actual legal phrase, but there may be some linguistic principle at work that I'm unaware of (it wouldn't be the first time)." (also see Droit sans honneur)