David Warren, standing on guard against Canada’s moral decline, has declared in the Ottawa Citizen that the recent Ontario Appeals Court decision recognizing three legal parents for a child of a lesbian couple is “a straight line to polygamy”, and that “polygamy follows multiple parentage as night follows day”. This is a familiar argument from social conservatives and has been used frequently to oppose legalization of gay marriage. As Warren writes, “it likewise followed from same-sex "marriage" - for if the institution cannot be restricted to one man and one woman, how otherwise can it be restricted?” Not to worry - there are plenty of reasons to support gay marriage (and allow “multiple parentage”) and still criminalize polygamy.
Even rabid libertarians acknowledge that not all individual rights are worthy of protection. John Stuart Mill, in his great essay “On Liberty”, laid the framework that has guided most western common law rights traditions: he wrote that individuals are entitled to life, liberty and property rights only so far as the exercise of those rights does not harm the rights of others. You may have the right to keep plutonium in your garden shed, but if it makes your neighbours sick or you are planning to build a weapon of mass destruction with it, then the state is justified in restricting this right to property.
It is difficult, in my mind, to argue that gay marriage infringes on the rights of anyone else. If a homosexual couple gets married, I can’t see how this significantly harms heterosexual couples or society at large. Similarly, if the state recognizes that a child has three legal parents, I don’t find the argument that this harms children very convincing. I think it makes sense from a libertarian perspective for the state to recognize that there is no valid reason for people not to exercise their liberty in this regard.
However, a very strong case can be made that polygamy does create harm. First of all, let us recognize that in societies that practice polygamy, it almost always means that one man has multiple wives, and not the other way around. In a population that statistically has a 50-50 split between males and females, and where males take multiple wives, the logical result is that many young men are prevented from taking wives of their own. The result in these communities is that surplus young men are frequently ostracized or banished from their communities against their will. This phenomenon is well documented in polygamist communities in the U.S. and Canada. This alone would justify the state’s intervention in limiting a man’s right to take multiple wives.
Furthermore, polygamist communities have a disturbingly high rate of incest, child abuse and wife battering. In Utah, where approximately 2% of the population are practicing polygamists in spite of a legal ban on plural marriage, the Los Angeles Times reported in 2001 that polygamist communities had extraordinarily high levels of these crimes, as well as widespread reliance on welfare, unusual levels of child poverty, wide-ranging tax fraud, limited education, and over-taxed public services. It is difficult to prosecute polygamy in Utah because the victims in these cases rarely press charges and it is almost impossible to compel witnesses to testify. However, there is no doubt in most people’s minds (including most Mormons) that polygamy should be illegal - the harm it produces far outweighs the rights to liberty of its practitioners. The state is fully justified in prohibiting it.
Opponents of gay marriage (and now “multiple parents”) argue that once the precedent for “non-traditional” family arrangements has been set, there is now no argument for continuing to insist that other non-traditional practices like polygamy remain illegal. Nonsense. The state has imposed limits on heterosexual marriage for centuries; the courts have upheld traditional taboos against marrying your mother, or your sister, or your dog. It is a legal requirement for heterosexuals to limit the number of their spouses to one. Homosexual marriage has the same legal limits - the centuries-old common law traditions have not been overturned, they have been extended, to include gay couples.
Gay marriage is now legal because its opponents could not muster up enough support for the argument that it caused harm to society. Fair enough. However, it would be difficult to make the same argument for polygamy, and the courts can and will recognize this. In my opinion, the moral floodgates have not been opened - everyone take a pill and relax.