In cultures where monogamy is mandated, bigamy is the act of entering into a marriage with one person while still legally married to another. A legal or de facto separation of the couple does not alter their marital status as married persons. In the case of a person in the process of divorcing their spouse, that person is taken to be legally married until such time as the divorce becomes final or absolute under the law of the relevant jurisdiction. Bigamy laws do not apply to couples in a de facto or cohabitation relationship, or that enter such relationships when one is legally married. If the prior marriage is for any reason void, the couple is not married, and hence each party is free to marry another without falling foul of the bigamy laws.
Bigamy is a crime in most countries that recognise only monogamous marriages. When it occurs in this context often neither the first nor second spouse is aware of the other. In countries that have bigamy laws, with a few exceptions (such as Egypt and Iran), consent from a prior spouse makes no difference to the legality of the second marriage, which is usually considered void.
History of anti-bigamy laws
Even before Christianity became the official religion of the Roman Empire, Diocletian and Maximian passed strict anti-polygamy laws in 285 AD that mandated monogamy as the only form of legal marital relationship, as had traditionally been the case in classical Greece and Rome. In 393, the Roman Emperor Theodosius I issued an imperial edict to extend the ban on polygamy to Jewish communities. In 1000, Rabbi Gershom ben Judah ruled polygamy inadmissible within Ashkenazi Jewish communities living in a Christian environment.
Most western countries do not recognize polygamous marriages, and consider bigamy a crime. Several countries also prohibit people from living a polygamous lifestyle. This is the case in some states of the United States where the criminalization of a polygamous lifestyle originated as anti-Mormon laws, although they are rarely enforced.
In diplomatic law, consular spouses from polygamous countries are sometimes exempt from a general prohibition on polygamy in host countries. In some such countries, only one spouse of a polygamous diplomat may be accredited, however.
China: Illegal. Up to 2 years' imprisonment, and up to 3 years for bigamy with soldiers (but tolerated for some minorities, such as Tibetans, in some rural areas in the south-west).
Colombia Illegal with exceptions (such as religion). Although bigamy no longer exists as a lone figure in the Colombian judicial code marrying someone new without dissolving an earlier marriage may yield to other felonies such as civil status forgery or suppression of information.
Malaysia: Illegal for non-Muslims under federal jurisdiction. Under section 494 of Chapter XX of the Penal Code, non-Muslim offenders found guilty of bigamy or polygamy can be punished up to 7 years' imprisonment. Bigamy or polygamy is legal only for Muslims with restrictions under state jurisdiction, rarely practiced.
Thailand: Prior to October 1, 1935, polygamy in Thailand could be freely practiced and recognised under civil law. Since its abolition, it is still practiced and widely accepted in Thailand, though no longer recognised, as the law states "A man or a woman cannot marry each other while one of them has a spouse."