Catechists will study and understand the validity needed in the administration of the Sacraments. The validity of a Sacrament makes all the difference in whether we truly received the Sacrament or not.
In theology we distinguish between the valid and the licit (lawful) administration of the Sacraments. A Sacrament is administered validly when it is administered in such a way as to effectively confer the graces which Christ intends to confer through the sacramental sign. Validity, then, has to do with the actual conferral of grace through the administration and reception of a particular Sacrament.
Liceity goes beyond validity, though the licit administration assumes a Sacrament’s prior validity. (If the Sacrament is invalid then it cannot be licit.) A Sacrament is administered licitly when the liturgical conditions established by Christ and the Church for the Sacrament’s administration are faithfully observed. The proper conditions for administering the Sacraments are given in the Code of Canon Law. It is possible for a Sacrament to be administered validly but not licitly, as when a layperson confers Baptism in the absence of urgent necessity. Questions about validity should be studied carefully and researched in Canon Law.
Liceity and Validity
Excerpt from Revised Basic Manual (p. 116)
The proper administration of a Sacrament requires that its conferral be at once licit and valid. The word licit means lawful, or legitimate. A Sacrament is administered licitly when the liturgical rites set forth by the Church for its conferral are faithfully observed, that is, when it is performed according to the laws of the Church. It is illicit when performed otherwise.
The validity of a Sacrament refers to its effectiveness. In a validly administered Sacrament, the grace that is signified is actually conferred through the required conditions of proper matter (or in some cases quasi-matter), form (the prescribed words), and circumstances. “Proper matter” is the material symbol (such as water, oil, bread, wine or physical gestures like imposition of hands). “Quasi-matter” is a personal, spiritual act (such as sin, sorrow and repentance) to be manifested or made sensible or like matter (as in the confession of sins). In order to administer it validly, the minister of a Sacrament must have the intention of doing what the Church desires.
A Sacrament can only be conferred licitly if it is conferred validly. For example, a priest may have every intention of confecting the Holy Eucharist at Mass, but if improper matter such as grape juice is used instead of wine, the Sacrament is not valid. In this case, because the Sacrament is not valid, neither can it be licit. (For Advanced Course lessons 17 to 24.)