The (canon) law of the Church requires that the diocesan bishop establish a tribunal to assist with the judicial aspect of his pastoral leadership of the diocese. The purpose of the tribunal is to assure that the rights of individuals and Church entities are upheld and protected, that all ministerial acts of the Church are carried out properly and validly and, if necessary, to declare sanctions for offenses. The tribunal staff, especially the judicial vicar, the tribunal coordinator and the diocesan judges, work closely with clergy and other ministers in parishes, as well as other diocesan staff, to give canonical advice and to assist with canonical issues that many arise in the course of their ministry.
In practice, however, the tribunal deals primarily with marriage cases. In all tribunal matters, including marriage nullity and/or dissolution cases, the tribunal is obliged to follow the procedural law of the Church.
Since the Church upholds the indissolubility of marriage, any person wishing to enter a marriage must be free of the impediment of any previous marriage(s). This also applies to those who are coming into the Catholic Church through the OCIA process and have one or more marriages prior to their current one (even, in most cases, if those were not religious marriages). It is not possible to predict either the outcome or the duration of any case. Therefore, no plans for a subsequent marriage or other sacrament should be made until a final decision is issued by the tribunal.
For those who require a marriage case of some type, the first step is to contact a priest or deacon in their local parish. He will assist with the preliminaries and submit the appropriate request to the tribunal, which thereafter works directly with the petitioner.