A marriage is not valid if it does not comply with the conditions laid down by the law. Foreign marriages may not be recognized if the parties were considered as not being competent to enter into marriage by the law of the country involved. Non-recognition of marriage may cause complications regarding the legitimacy of children, their nationality, property rights and liabilities; and in the event of divorce.
Non-valid marriages may include bigamous marriages, child marriage, polygamous marriage, and marriage forbidden on racial, ideological or other grounds. The former Soviet Union forbade the marriage of Soviet citizens to foreigners. In many African countries, race inter-marriage is forbidden. Under Islamic law a woman may not marry a non-Muslim, and under Jewish law husband and wife must be Jew and Jewess, but either of them may become so after having been received into the Jewish community. Bigamous and polygamous marriages will be invalid where they are not accepted by the law. Child marriage is considered invalid in most countries, but may be accepted as a custom, as in India.