§1. The person competent to accept a libellus seeking a dispensation is the diocesan bishop of the domicile or quasi-domicile of the petitioner, who must arrange for the instruction of the process if the petition is well founded.
§2. If the proposed case has special difficulties of the juridical or moral order, however, the diocesan bishop is to consult the Apostolic See.
§3. Recourse to the Apostolic See is available against a decree by which a bishop rejects a libellus.
Source: Code of Canon Law (Vatican.va)