Grounds for invalidating

is a judgment on the part of an ecclesiastical tribunal determining that a marriage was invalidly contracted or, less frequently, a judgment determining that ordination was invalidly conferred.A matrimonial nullity trial, governed by the church's canon law, is a judicial process whereby a canonical tribunal determines whether the marriage was void at its inception (ab initio).A "Declaration of Nullity" is not the dissolution of an existing marriage (as is a dispensation from a marriage ratum sed non consummatum and an "annulment" in civil law), but rather a determination that consent was never validly exchanged due to a failure to meet the requirements to enter validly into matrimony and thus a marriage never existed.

Certain conditions are necessary for the marriage contract to be valid in canon law.Lack of any of these conditions makes a marriage invalid and constitutes legal grounds for a declaration of nullity.Accordingly, apart from the question of diriment impediments dealt with below, there is a fourfold classification of contractual defects: defect of form, defect of contract, defect of willingness, defect of capacity.For annulment, proof is required of the existence of one of these defects, since canon law presumes all marriages are valid until proven otherwise.