In some monastic libraries inscriptions can be found menacing excommunication for people that stole the books. In one documented historical case, pope Clemens XII in 1734 proclaimed that whoever would steal a book from the public library of Velletri would be excluded from the Communion. I remember seeing a similar menace in the central university library of Bologna, the Archiginnasio.

The secular library of Alessandria (in Piedmont) was founded in 1667, and it was associated with the local tribunal; a papal bull specifies that thieves of books or handwritten texts incur excommunication latae sententiae.