Most visitors to this page want to know three things: whether their circumstances fall within what the Church regards as grounds of nullity, which tribunal will hear the cause, and what happens in civil law.
It is not an annulment
English usage speaks of “annulment”, and the word misleads. A divorce dissolves a bond that existed and was valid, and takes effect from the judgment onwards. A declaration of nullity finds that the bond never validly came into being, because of a defect already present when consent was exchanged; its effect reaches back to the wedding day. Nothing is dissolved: what appeared to be a marriage is found never to have been one.
From this follows the misunderstanding most common among those approaching a tribunal for the first time. What matters is not what happened during the marriage, but what the condition of the parties was at the moment consent was given. Later events count only in so far as they reveal that original condition.
Grounds of nullity
Canon law knows no general nullity. One or more specific grounds must be pleaded — incapacity to consent, simulation, deceit, error, force or fear, condition, among others — and the investigation will be confined to those.
Which tribunal
A cause is ordinarily brought before the tribunal of the place of the wedding, of the respondent’s domicile, of the petitioner’s domicile, or of the place where most of the evidence is to be gathered. The Apostolic Tribunal of the Roman Rota ordinarily hears appeals, and in certain cases sits at first instance.
The process after the 2015 reform
The motu proprio Mitis Iudex Dominus Iesus reshaped the process, adding to the ordinary procedure a shorter one before the diocesan Bishop, available only where both spouses petition together and the nullity is manifest from the circumstances. The shorter process is an exception, not the ordinary route.
Effect in Italian law
An ecclesiastical sentence has no civil effect in Italy of itself. Recognition requires separate proceedings before the Court of Appeal, which may be refused. This is the stage at which a favourable canonical outcome is most often lost.
This matters even where the cause was heard entirely outside Italy: a party who obtains a declaration of nullity abroad has ordinarily no reason to suspect that an Italian question arises — unless the wedding itself took place in Italy, which is far from uncommon.