Council of Trent: Session XXIV, Reformation of Marriage, Chapter VIII

CHAPTER VIII. Concubinage is severely punished.

It is a grievous sin for unmarried men to have concubines; but it is a most grievous sin, and one committed in special contempt of this great sacrament, for married men also to live in this state of damnation, and to have the audacity at times to maintain and keep them at their own homes even with their own wives. Wherefore, the holy Synod, that it may by suitable remedies provide against this exceeding evil, ordains that these concubinaries, whether unmarried or married, of whatsoever state, dignity, and condition they may be, if, after having been three times admonished on this subject by the Ordinary, even ex officio, they shall not have put away their concubines, and have separated themselves from all connexion with them, they shall be smitten with excommunication; from which they shall not be absolved until they have really obeyed the admonition given them. But if, regardless of this censure, they shall continue in concubinage during a year, they shall be proceeded against with severity by the Ordinary, according to the character of the crime. Women, whether married or single, who publicly live with adulterers or with concubinaries, if, after having been three times admonished, they shall not obey, shall be rigorously punished, according to the measure of their guilt, by the Ordinaries of the places, ex officio, even though not called upon to do so by any one; and they shall be cast forth from the city or diocese, if the Ordinaries shall think fit, calling in the aid of the Secular arm, if need be; the other penalties inflicted on adulterers and concubinaries remaining in their full force.

Translation: J. Waterworth, The Canons and Decrees of the Council of Trent (1848), Hanover Historical Texts Project transcription (1995).