Laws About and Affecting Non-Monogamy

Standard disclaimer: I am not a lawyer or legal expert. For legal advice consult a lawyer in your area.

Bigamy, Adultery, and other Laws

Laws about and affecting non-monogamy are very common throughout the world. These laws vary widely, but in general they will take a few forms.

Laws against bigamy

Laws against bigamy are most common in Europe and parts of the world which have (forcibly or otherwise) adopted European cultural ideals. Laws against bigamy are less common in parts of Africa, the Middle East, and Asia, where some countries still allow polygyny (having multiple wives).

Bigamy is having two spouses. Some laws refer to polygamy instead of bigamy, but the basic idea is the same–you are only allowed to marry one person.

Bigamy laws that end there are called “simple bigamy.” For most polyamorous relationships and other forms of non-monogamy this, in and of itself, isn’t a legal problem. While it would be nice to be able to marry all the people we love, it doesn’t stop us from being with them. An example of “simple bigamy” can be found in Norway* (thanks to Norwegianpoly for pointing this out!), where you can live with two partners, as long as you aren’t legally married to both of them.

The real challenge comes from the bigamy laws that extend to more than simple bigamy. Some bigamy laws (such as the one in Utah the Brown family challenged) make it illegal to live together as if you were married. Other bigamy laws make it illegal to present yourself as married to more than one person.

These versions of bigamy laws can cause problems for poly folk and other non-monogamous relationships  (such as the Brown’s). It is worth noting that the law in the Brown’s case was used to punish them for daring to speak out about their relationship. Their family was well known in their community, but no one was interested in prosecuting them until they started “embarrassing” the state of Utah.

It is not just the existence of these laws that are a problem, but the way they are enforced.

Laws Against Adultery and Laws Against Fornication

While not universal, laws prohibiting adultery and fornication are extremely common. Legal sentences for these crimes vary from minor fines to execution. In the US, non-monogamous folk charged with fornication or adultery could probably challenge the law using Lawrence v. Texas.

Laws regarding adultery vary in one important way. In some jurisdictions, a charge of adultery must be brought by the “betrayed” spouse. Married poly folk who live in these areas cannot be charged with adultery as long as their spouse doesn’t want to bring charges–and if you are actually practicing ethical and consensual relationships, your spouse would have no reason to bring charges.

In other jurisdictions, anyone can charge you with adultery, whether or not your spouse supports your relationships.

Common Law Marriage

Okay, for folks in a few parts of the world (including 9 US states), here’s the monkey wrench in everything. Common law marriage is also known as sui juris marriage, informal marriage, or marriage by habit and repute.

Here’s the way common law marriage works. You live with some one for a while and present yourselves as husband and wife, BAM! you’re married. No license, ceremony, certificate, or Justice of the Peace needed.

The specifics of common law marriage vary. Israel includes an “economic test” in its law regarding common law marriage. (Israel is also unusual in that the state will only recognize traditional marriage ceremonies from Orthodox, Christian and Muslim religious authorities, so allowing “common law” marriage is a way for the state to recognize non-Orthodox (or equivalent) marriages and interfaith or civil marriages without needing to recognize the right of non-Orthodox (or equivalent) religious figures to perform a marriage. Texas does not include any test other than the couple declaring their intent to be married and living together. (Edited 8/30/15, thanks to Stav for corrections re: marriage in Israel)

I do not know of any jurisdiction where you can end up with a common law marriage without either the intent to get married or actively presenting yourselves to the world as married. Update: Thanks to Mel Millar for pointing out that in parts of Canada you can end up common law married without the intent to get married, and the result is screwing up access to government benefits for poly folk (and many monogamous folk) in Ontario.

This is where common law marriage can seriously trip up poly folk. Because we are not legally able to marry all of our spice, it is not uncommon for poly folk to declare that they consider themselves married and live together as if they were married. In which case, depending on where you live, you have just met the standards for common law marriage and may be prosecuted for bigamy, and Bonus! are now guilty of adultery and fornication. Gotta love that hat trick.

Thankfully, common law marriages are extremely uncommon around the world, and pretty much unheard of outside of the Anglosphere (Israel, as noted above, being an unusual exception).


It’s popular in some poly discussions to put forward the idea that the legal standing of poly relationships only applies to some types of polyamory or to some poly folk but not others. These laws, especially in combination, can and do affect all of us.

Luckily for poly folk, the countries where polyamory is most popular are also, by and large, countries that are less likely to persecute these crimes, and if they prosecute tend to have less extreme sentencing. (Tend to, not always do. I believe there is one state in the US with a 10-year prison term for adultery.) Additionally these laws are rarely used in many countries with a significant poly population because, by and large, both police and politicians have better things to do with their time.

That said, as noted in the Brown’s case, these laws can and have been used as ways to legally persecute non-monogamous families who draw too much attention to themselves. If polyamory and/or non-monogamy becomes a popular political target (which grows increasingly possible as conservatives in various countries recognize they are losing their battle against LGBT), then we may find use of these statutes to attack non-monogamy increasing.

Next Sunday we’ll be checking out how laws affect where and how poly folk can make their homes.

*One political party in Norway is apparently pushing to make polygamy legal. If polygamy is legal, anti-bigamy laws disappear, and there are lots of happy poly people. Fingers crossed for Norway!


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