CODEX IURIS CANONICI
CAN. 1325.
§ 3. Caveant catholici ne disputationes vel collationes, publicas praesertim, cuм acatholicis habeant, sine venia Sanctae Sedis aut, si casus urgeat, loci Ordinarii.
Catholics are to avoid disputations or conferences about matters of faith with non-Catholics, especially in public, unless the Holy See, or in case of emergency the Ordinary of the place, has given permission (c. 1325, §3).