Appendix 2 - Impediments to Marriage
One or both of the parties to the intended marriage will be under the age of 18 years of age, on the date of marriage (unless an exemption from this provision is granted by the Circuit Family Court or High Court).
One or both of the parties to the intended marriage is, or both are, already party to a subsisting marriage or a subsisting civil partnership.
One of both parties is incapable by reason of intellectual disability or mental illness of understanding the nature and effect of the marriage contract (a medical report is required to establish the facts in such cases.)
The parties are of the same sex
The civil partnership would be void by virtue of the prohibited degrees of relationship and affinity.
Prohibited Degrees of Kindred and Affinity
A man may not marry his:
Grandmother
Grandfather's Wife
Wife's Grandmother
Father's sister
Mother's sister
Father's brother's wife
Mother's brother's wife
Wife's father's sister
Wife's Mother's Sister
Mother
Stepmother
Wife's mother
Daughter
Wife's daughter
Son's wife
Sister
Son's daughter
Daughter's daughter
Son's son's wife
Daughter's son's wife
Wife's son's daughter
Wife's daughter's daughter
Brother's daughter
Sister's daughter
Brother's son's wife
Sister's son's wife
Wife's brother's daughter
Wife's sister's daughter
A woman may not marry her:
Grandfather
Grandmother's Husband
Husband's grandfather
Father's brother
Mother's brother
Father's sister's husband
Mother's sister's husband
Husband's father's brother
Husband's mother's brother
Father
Stepfather
Husband's father
Son
Husband's son
Daughter's husband
Brother
Son's son
Daughter's son
Son's daughter's husband
Daughter's daughter's husband
Husband's son's son
Husband's daughter's son
Brother's son
Sister's son
Brother's daughter's husband
Sister's daughter's husband
Husband's brother's son
Husband's sister's son
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感觉这些不能娶的硬性规定多了去了，在中国很常见啊