“So, are you legally married, you didn’t get divorced?” asked one clerk.

“We’ll have to deny that, let me go grab the other supervisor real quick so I can get confirmation but as far as I’m aware you can’t be married to two people at the same time,” said another clerk.

That was the exchange that took place at Yellowstone County Courthouse in Montana last week when a married man applied for a (second) marriage license to wed another woman. After the Supreme Court issued its Obergefell decision last week, making gay marriage legal throughout the country, it was probably inevitable that polygamous groups would begin to challenge state statutes that have declared plural marriage a misdemeanor.

In a piece on the website RealClearPolitics, Sean Trende makes the argument that polygamous marriage is unlikely to become acceptable or legal anytime soon. Whereas most Americans know someone who is gay, the same cannot be said for polygamous groups. “It is one thing to say that ‘gays,’ as some sort of abstraction, should not marry; it is another to say that your neighbors’ kid is stuck living alone. The same simply is not true of polygamists, who tend to live apart from society (not entirely by choice). This probably isn’t how we should make moral decisions, but I don’t have much doubt that it is how an awful lot of people do make these decisions.”

But it is the fact that polygamists do tend to live apart that should make us think twice about whether polygamy should be legal as well. Increasingly, it seems that polygamy is simply incompatible with democratic values.

In a piece she wrote for the Wall Street Journal in 2011, Rose McDermott, a professor of political science at Brown University, wrote about her research on polygamy, which is practiced by substantial subcultures in France, Britain, and the U.S., as well as across religious lines in Africa.

According to the information I have helped to collect in the Womanstats database, women in polygynous communities get married younger, have more children, have higher rates of HIV infection than men, sustain more domestic violence, succumb to more female genital mutilation and sex trafficking, and are more likely to die in childbirth. Their life expectancy is also shorter than that of their monogamous sisters. In addition, their children, both boys and girls, are less likely to receive both primary and secondary education.

There are those who might argue that it is precisely because of the illegality of polygamy that these groups are kept from joining mainstream society. But McDermott suggests that another factor is at work:

Polygynist cultures need to create and sustain an underclass of unmarried and undereducated men, since in order to sustain a system where a few men possess all the women, roughly half of boys must leave the community before adulthood. Such societies also spend more money on weapons and display fewer social and political freedoms than do monogamous ones.

When small numbers of men control large numbers of women, the remaining men are likely to be willing to take greater risks and engage in more violence, possibly including terrorism, in order to increase their own wealth and status in hopes of gaining access to women.

For an interesting description of some of these problems in the ghettoized suburbs of Paris, see, for instance, Jane Kramer’s 2004 New Yorker piece. Along with female genital mutilation, a polygamous structure is fundamental to the structure of these communities, and related to their general sense of lawlessness.

Prosecutors in the U.S. have found it notoriously difficult to police polygamous marriage. After all, if people don’t apply for official marriage licenses, it’s hard to accuse them of being married to more than one person. But because polygamy has so many clear side effects—girls are typically assigned to a man at an age far below the age of consent, large groups of boys are often expelled from these communities, children are generally kept from receiving any kind of education—it is possible to know when and where polygamy is being practiced.

Whether or not it seems like the next legal step on this “slippery slope,” polygamy is a much different animal from gay marriage. Letting the men who run these communities have free rein and the stamp of approval from the federal government will only deepen the social problems polygamy causes. And the victims will become more helpless than they already are.