19 In discharging their apostolic office, which concerns the salvation of souls, bishops per se enjoy full and perfect freedom and independence from any civil authority. Hence, the exercise of their ecclesiastical office may not be hindered, directly or indirectly, nor may they be forbidden to communicate freely with the Apostolic See, or ecclesiastical authorities, or their subjects. Assuredly, while sacred pastors devote themselves to the spiritual care of their flock, they also in fact have regard for their social and civil progress and prosperity. According to the nature of their office and as behooves bishops, they collaborate actively with public authorities for this purpose and advocate obedience to just laws and reverence for legitimately constituted authorities.
Source: Christus Dominus (Vatican.va)