Canon 27 (1179), as printed in Denzinger no. 401

Chapter 27. As blessed Leo says, although the discipline of the Church, content with the judgement of a priest, does not carry out bloody punishments, it is nevertheless assisted by the enactments of catholic princes, so that men often seek a salutary remedy while they fear that bodily punishment will come upon them. Therefore, since in Gascony, in the Albigensian territory, in the region of Toulouse and in other places the condemned perversity of the heretics — whom some call Cathars, others Patarenes, others Publicani, others by other names — has so far prevailed that they no longer practise their wickedness in secret, as some do, but make their error known publicly and draw the simple and the weak into agreement with them: we decree that they, and those who defend and harbour them, lie under anathema; and under anathema we forbid anyone to presume to keep or foster them in his houses or on his land, or to carry on trade with them.