The Church teaches that marriage is a covenant before God in which one man and one woman enter a faithful, lifelong partnership of love and life for their mutual fulfillment, and the procreation and education of children. For baptized Christians, whether Catholic or not, marriage is a sacrament instituted by Christ as a special means of holiness. Yes, the Church teaches that a binding, sacramental marriage cannot be dissolved by any human power. This teaching is founded on the Gospel of Christ. It is reinforced in the Epistles of Saint Paul, and has been upheld through centuries of Christian tradition.
Church law holds that every marriage is indissoluble unless the contrary is proved.
The Church Tribunal will issue a declaration of invalidity only if it finds, after careful study, that there is sufficient evidence to declare that a particular marriage lacked some element of a binding and sacramental union. A Tribunal is a court set up by the Church to decide questions of church law. The Tribunal deals with all aspects of church law, not only with questions about the validity of marriage. Every diocese has a Tribunal that deals with these questions on the local level. There are also Appeals Tribunals at the regional level, and Vatican Tribunals in Rome.