Canon 749. §1 In virtue of his office the Supreme Pontiff is infallible in his teaching when, as chief Shepherd and Teacher of all Christ’s faithful, with the duty of strengthening his brethren in the faith, he proclaims by definitive act a doctrine to be held concerning faith or morals.

§2 The College of Bishops also possesses infallibility in its teaching when the
Bishops, gathered together in an Ecumenical Council and exercising their magisterium as teachers and judges of faith and morals, definitively declare for the universal Church a doctrine to be held concerning faith or morals; likewise, when the
Bishops, dispersed throughout the world but maintaining the bond of union among themselves and with the successor of Peter, together with the same Roman Pontiff authentically teach matters of faith or morals, and are agreed that a particular teaching is definitively to be held.

§3 No doctrine is understood to be infallibly defined unless this is manifestly demonstrated.

§1. Infallibilitate in magisterio, vi muneris sui gaudet Summus Pontifex quando ut supremus omnium christifidelium Pastor et Doctor, cuius est fratres suos in fide confirmare, doctrinam de fide vel de moribus tenendam definitivo actu proclamat.

§2. Infallibilitate in magisterio pollet quoque Collegium Episcoporum quando magisterium exercent Episcopi in Concilio Oecumenico coadunati, qui, ut fidei et morum doctores et iudices, pro universa Ecclesia doctrinam de fide vel de moribus definitive tenendam declarant aut quando per orbem dispersi, communionis nexum inter se et cum Petri successore servantes, una cum eodem Romano Pontifice authentice res fidei vel morum docentes, in unam sententiam tamquam definitive tenendam conveniunt.

§3. Infallibiliter definita nulla intellegitur doctrina, nisi id manifeste constiterit.