Marriage, in the theology of Catholicism, is an inseparable bound between a man and a woman, created by human contract and ratified by divine grace.

The nature of the contract requires that the two participants be one man and one woman, that they be free to marry, that they willingly and knowingly enter into a valid marriage contract, and that they validly execute the performance of the contract.

On the exact definition of each of these steps hinge all the arguments and technical points involved in annulmentss, and annulment disputes (eg, the most famous, that of Henry VIII). Catholic canon law covers this subject in detail.

Free to marry

The participants in a marriage contract must be free to marry, and to marry each other. That is, they must be an unmarried man and woman, not subject to vows of celibacy, and not related in such a degree as to prohibit marriage. They cannot be permanently incapable of marital relations (i.e. impotent), though they need not be fertile.

Intent to marry

The participants must knowingly and willingly intend to marry. This precludes marriages in which one party was forced, drugged, or statutorily incapable of such intent (due to physical age or mental incapacity). Such a marriage is invalid. A marriage in which one party is misled may be either invalid or illicit, depending on the nature of the fraud.

Intend Catholic marriage

The participants must intend Catholic marriage specifically. That is, they must intend an exclusive, lifelong, childbearing union. It is taught currently that they need not specifically intend to have children, but they must intend a union which is by its nature fruitful; that is, they must be open to childbearing.

Actually marry

The husband and wife must validly execute the marriage contract. If either is Catholic, this requires a sacramental Catholic marriage ceremony for validity.

Validity

A marriage may be somewhat defective and yet still be valid; such a marriage is illict. A marriage which was sufficiently defective as to not meet the required criteria is invalid, and the participants are considered to not have actually married (although their children may still be considered to be legitimate).

Nullity

Catholic theology teaches that a validly contracted marriage is accompanied by divine ratification, creating an idissoluble union; therefore, no divorce is possible.

An annulment is a declaration that the marriage is deemed to have been invalid. Therefore, an annulment is granted with some finding of lack of validity in the marriage itself, at the time of the marital contract; in theory, behavior subsequent to the contract should not be directly relevant, except as post facto evidence of the validity or invalidity of the contract. That is, behavior subsequent to the contract cannot actually change the validity of the contract.

Annulment and divorce, therefore, differ in both in rationale and effect; an annulment is a finding that the original marriage was invalid (denying that the marriage every truly existed), whereas a divorce is a dissolution of an existing marriage, but without undoing its historical existence.

Glossary