Catholic Church: Sometimes the canons of councils insist on the separation of the parties who have violated the law, which implies that the marriage was void; sometimes, on the contrary, they exact only an expiation or reparation, without dissolving the conjugal union, which implies that the marriage was valid though more or less in opposition to the law.
The ancient canonical texts do not give a complete list of impediments, much less a general theory concerning them. It is only at the end of the twelfth century that we find, for the first time, the use of the word "impediment" in its technical sense, together with a catalogue of matrimonial impediments. In his "Decree", Gratian neither speaks definitely, nor does he give a satisfactory list; nor does Peter Lombard in his "Sentences". About 1190 Bernard of Pavia uses freely the expression, which became classical, "impedit contrahendum et dirimit contractus", and further he enumerated the impediments: "sunt autem qu‘ matrimonium impediunt xiv", but his list is not definitive; the technical names of each impediment remain for some time longer unsettled. However the doctrine of the School soon becomes fixed and with it the terminology. The distinction between diriment and prohibitory impediments is sharply marked, and a more or less successful attempt is made to classify the diriment impediments. Their number is not yet determined, not because the doctrine is uncertain, but because several of them may be included under the same title. Certain canonists try to limit them to the quasi sacred number fourteen (twice seven); others reckon twelve, sixteen, or even more.
Catholic Church: According to Catholic canon law, the fundamental idea of an impediment to matrimony is contained implicitly in the prohibitions of Leviticus and some ancient canonical texts; in the latter may be discovered the basis of the celebrated distinction between diriment impediments which render a marriage null and void, and prohibitory impediments which only render it illicit.
Prohibitory impediments include:
1. Prior betrothal, whereby any other marriage would be a violation of that right.
2. Conflicting vow, namely a vow of chastity.
3. Mixed marriage, namely with a non-baptized Catholic.
4. Vetitum Ecclesio, namely a veto by a bishop.
5. Forbidden times for marriage, namely from Advent to the Epiphany, and from Ash Wednesday to Low Sunday.
Diriment impediments, namely those that render marriage null and void, include:
1. Impediments arising from: the physical incapacity of the subject (impuberty and impotency); presumption of want of consent, abduction, namely the incapacity of the abductor of contracting valid marriage with the woman whom he has abducted, until she has first been allowed to go free; disparity of worship renders void the marriage of a Christian with an infidel, that is, of a baptized person with one who is unbaptized; prior marriage, namely in the case of a previous matrimonial engagement whereby any marriage of a married person was rendered void during the lifetime of the person to whom he or she has been validly married; prior relationship, namely: natural relationship or community of blood to the fourth degree or generation; an alliance which establishes a bond of relationship between each of the married parties and the blood relations of the other, and forbids marriage between them to the fourth degree; public decorum, a legal anticipation of affinity; spiritual relationship, prohibiting marriage between those taking an active part in the rites of Christian initiation, baptism, and confirmation; arising from the legal relationship of adoption.
2. Clandestinity.
3. Defect of consent insanity or total ignorance, or error.