Approbation, in Catholic canon law, is an act by which a bishop or other legitimate superior grants to an ecclesiastic the actual exercise of his ministry.
The necessity of approbation, especially for administering the sacrament of penance, was expressly decreed by the Council of Trent so, except in the case of imminent death, the absolution by a non-approved priest would be invalid.
By bishop is meant also his vicar general, the diocesan administrator during the vacancy of a see, or any regular prelate who has ordinary jurisdiction over a certain territory.
The bishop may wrongfully but validly refuse his approbation, without which no priest may hear confessions.
A confessor's jurisdiction may be restricted to various classes of persons; for example to children or to men, without the right to hear women.