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On the whole UK law does not permit polygamous marriage (see: Marriage), where either party is considered to be married already. Such marriages are considered void (see: Void Marriage).

However, many states do permit polygamy, and it is part of their culture. There are cases where UK courts will accept a person as being married, even polygamously, where both partners were domiciled outside the UK at the time of the marriage (see: Domicile). Such a marriage will be 'converted' to a monogamous marriage on taking up residence in the UK.