Validity and liceity are concepts in the Catholic Church. Validity designates an action which produces the effects intended; an action which does not produce the effects intended is considered "invalid". Liceity designates an action which has been performed legitimately; an action which has not been performed legitimately is considered "illicit". Some actions can be illicit, but still be valid.

Catholic canon law also lays down rules for licit, also called lawful, placing of the act, along with criteria to determine its validity or invalidity. Valid but illicit or valid but illegal (Latin: valida sed illicita) is a description applied in the Catholic Church to describe either an unauthorized celebration of a sacrament or an improperly placed juridic act that nevertheless has effect. Validity is presumed whenever an act is performed by a qualified person and includes those things which essentially constitute the act itself as well as the formalities and requirements imposed by law for the validity of the act.

The 1983 Code of Canon Law states: "Except in a case of necessity, it is unlawful for anyone without due permission to confer baptism outside his own territory, not even upon his own subjects". In the Latin Church, administration of baptism is one of the functions especially entrusted to the parish priest.

However, according to the same Code, any person, even someone not baptized, can baptize, if he has the required intention. The intention required is to will to do what the Catholic Church does when she baptizes, and to apply the Trinitarian baptismal formula.

In 2008, the Congregation for the Doctrine of the Faith (CDF) stated the baptism formulae "I baptize you in the name of the Creator, and of the Redeemer, and of the Sanctifier" and "I baptize you in the name of the Creator, and of the Liberator, and of the Sustainer", were invalid.

In 2020, the CDF stated the formula "We baptize you in the name of the Father and of the Son and of the Holy Spirit" was invalid for the purposes of conferring baptism. This made it so Matthew Hood, a Catholic priest of Detroit who had been baptised by Mark Springer by this formula, was not considered a priest anymore (Hood was later properly baptised and ordained). This 2020 statement created other difficulties, as other people from Detroit had been baptised with the same formula by Springer, and other people had received sacraments from Hood since the latter's ordination 2017. Due to the same 2020 statement, another US priest, Andrés Arango, who had baptised using the same formula, had to properly baptise those he had invalidly baptised. Thomas Reese and retired sacramental theology Prof. Peter Fink have criticized the CDF statement, saying the "We" formula was valid.

In the Latin Church, a bishop is the ordinary minister of confirmation and he may licitly administer it to his own subjects everywhere and, in his own territory, even to Catholics who are not his subjects, unless their ordinary has expressly forbidden it. In the Latin Catholic Church, simple priests (presbyters) can validly and licitly confirm in some circumstances, such as when they baptize adults or receive them into the church and when there is danger of death.

Priests of the Eastern Catholic Churches can validly confer the sacrament on any Catholic, even a Catholic of the Latin Church, but they can do so licitly only on those who belong to their own particular church and on other Catholics who meet the conditions of either being their subjects or of being lawfully baptized by them, or of being in danger of death.