A reason for annulment is called a diriment impediment to the marriage. Prohibitory impediments (which no longer exist in the Latin Code, CIC83) make entering a marriage wrong but do not invalidate the marriage, such as being betrothed to another person at the time of the wedding; diriment impediments, such as being brother and sister, or being married to another person at the time of the wedding, prevent such a marriage in crisis from being contracted at all. Such unions are called putative marriages.
Diriment impediments include:
- Consanguinity
- Insanity precluding ability to consent
- Not intending, when marrying, to remain faithful to the spouse (simulation of consent)
- One partner had been deceived by the other in order to obtain consent, and if the partner had been aware of the truth, would not have consented to marry
- Abduction of a person, with the intent to compel them to marry (known as raptus), constitutes an impediment as long as they remain in the kidnapper’s power.
- Failure to adhere to requirements of canon law for marriages, such as clandestinity
- The couple killed the spouse of one of them in order to be free to marry.
- The couple committed adultery.
- The couple were under the influence of alcohol or drugs at the time of the marriage.
Some impediments can be dispensed, in which the Church exempts a couple, prior to the marriage, to the obligation to conform to the canon law. While some relationships cannot have the impediment of consanguity dispensed, a marriage can be sanctioned between cousins. This renders the marriage valid, and so non-annulable. You may in this case require some online marriage help. Again, if an invalid marriage has been contracted, and the diriment impediment can be removed, a convalidation or sanatio in radice can be performed to make the marriage valid.