Council of Trent: Session XXIII, Reformation, Chapter XV

CHAPTER XV. No one shall hear confessions, unless he be approved of by the Ordinary.

Although priests receive in their ordination the power of absolving from sins; nevertheless, the holy Synod ordains, that no one, even though he be a Regular, is able to hear the confessions of Seculars, not even of priests, and that he is not to be reputed fit thereunto, unless he either holds a parochial benefice, or is, by the bishops, after an examination if they shall think it necessary, or in some other manner, judged capable; and has obtained their approval, which shall be granted gratuitously; any privileges, and custom whatsoever, though immemorial, to the contrary notwithstanding.

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