Canon 1673. §1 In each diocese, the judge in first instance for cases of nullity or marriage for which the law does not expressly make an exception is the diocesan bishop, who can exercise judicial power personally or through others, according to the norm of law.

§2 The bishop is to establish a diocesan tribunal for his diocese to handle cases of nullity of marriage without prejudice to the faculty of the same bishop to approach another nearby diocesan or interdiocesan tribunal.

§3 Cases of nullity of marriage are reserved to a college of three judges. A judge who is a cleric must preside over the college, but the other judges may be laypersons.

§4 The bishop moderator, if a collegial tribunal cannot be constituted in the diocese or in a nearby tribunal chosen according to the norm of §2, is to entrust cases to a sole clerical judge who, where possible, is to employ two assessors of upright life, experts in juridical or human sciences, approved by the bishop for this task; unless it is otherwise evident, the same single judge has competency for those things attributed to the college, the praeses, or the ponens.

§5 The tribunal of second instance must always be collegiate for validity, according to the prescript of the preceding §3.

§6 The tribunal of first instance appeals to the metropolitan tribunal of second instance without prejudice to the prescripts of cann. 1438-1439 and 1444.