All persons may contract marriage unless forbidden by law. (Canon 1035)
An impedient impediement entails a grave prohibition to contrsact marriage, but it does not invalidate marriage contracted despite such impediment. A diriment impediment not only gravely forbids marriage, but makes its celebration null and void. (Canon 1036)
Diriment Impediments
Impediments are of minor or majjor decgree. The following are of minor degree:
1. Consangunuity in the third degree of the collateral line;
2. Affinity in the second degree of hte collateral line;
3. Public decency in the second degree;
4. Spiritual relationship;
Crime of adultery with the promise of marriage or attempted marriage even by mere civil ceremony. (Canon 1042)
A boy under sixteen years of age and a girl under fourteen cannot validly contract marriage. (Canon1067)
Antecedent and perpetual impotency, either on the part of hte man or the woman, whether known to the other party or not, and whether absolute or relative, annuls marriage by the very law of nature. (Canon 1068)
A person who is bound by a previous bond of marriage, though it be not a consumated marriage, cannot validly contract another marriage. (Canon 1069)
Persons in major orders cannot validly contract marriage. (Canon 1072)
Religious who have taken solemn vows, or whose simple vows have by the special law of the Holy See the power to annull marriage, cannot contract a valid marriage. (Canon 1073)
Canon 1074 provides for the invalidity of a marraige forced by abduction.
Canon 1075 provides for invalidity of marriage by those who are married and promise marriage.
1. In the direct line or consanguinuity marriaage is invalid between persons of all degrees ascending and descending, legitimate as well as natural ancestors or descendants.
2. In the collateral line, marriage is invalid between blood relations to the third degree inclusively, in such a manner, however, that the impediment is multilied only whenever the common stirpes is multiplied.
3. Marriage shall never be permitted if there is any doubt whether the parties are blood relations in any degree of the direct line, or in the first degree of hte collateral line. (Canon 1076)
That spiritual relationship only which is mentioned in Canon 768 invalidates marraige. (Canon 1079; this is between the minister and sponsors at Baptism and the one baptized.)
Impedient Impediments
It is gravely sinful to enter marriage under any impediment, but these do not invalidate the marraige.
Marriage is foribdden to those who have made the simple vow of virginity, of perfect chastity, not to marry, to receive major orders, or to embrace the religious life. (Canon 1058)
In those countries where the relationship arising from legal adoption makes marriage illicit according to the civil law, marriage is also illicit by Canon Law. Canon 1059)
Canon 1060: The Church, most solemnly and everywhere forbids marriages between a Catholic and a person enrolled in an heretical or schismatical sect. If there is danger of perversion for the Catholic party and the offspring, such marriage is forbidden also by the divine law. See the section on Traditionalist marriages.
Note well Pope Michael amended canon 1060 to make such marriages invalid in 1996. The decree on the illegitimacy of Traditionalist Ordinations restored the law as it was on October 9, 1958. This decree was issued on February 2, 2006 and therefore this provision was restored to the law above as of May 2, 2006.
The Church does not dispense from the impediment of mixed religion except under the following conditions: