§1. The diocesan bishop is to administer confirmation personally or is to take care that another bishop administers it. If necessity requires it, he can grant the faculty to one or more specific presbyters, who are to administer this sacrament.
§2. For a grave cause the bishop and even the presbyter endowed with the faculty of confirming in virtue of the law or the special grant of the competent authority can in single cases also associate presbyters with themselves to administer the sacrament.
Source: Code of Canon Law (Vatican.va)