Council of Trent: Session VI, On Justification, Canon XXIII

ON JUSTIFICATION

CANON XXIII.-lf any one saith, that a man once justified can sin no more, nor lose grace, and that therefore he that falls and sins was never truly justified; or, on the other hand, that he is able, during his whole life, to avoid all sins, even those that are venial,-except by a special privilege from God, as the Church holds in regard of the Blessed Virgin; let him be anathema.

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