One of William Eskridge and Darren Spedale's main points in Gay Marriage: For Better or Worse? is that when the northern European countries legalized same-sex marriage it did not open the door to legalizing every other kind of union. They specifically note that gay marriage has not led to legal polygamy. "Pandora's box was opened," they cheerfully assert, "and it was empty."
Last September, as Eskridge and Spedale were finishing their book, a married couple, Victor and Bianca de Bruijn, took advantage of the Netherlands' registered partnership law to add a second wife, Mirjam Geven. Geven met the de Bruijns through a chatroom, and soon left her husband to live with them. Registered partnerships were invented to allow homosexual couples to legalize their unions. As I noted yesterday, though, most of the people who have taken advantage of the law are heterosexual couples. The de Bruijn-de Bruijn-Geven union hit the trifecta – he is straight, and both women are bisexual.
Strictly speaking, the Netherlands has not legalized polygamy, because registered partnerships are not precisely marriages, but "marriage-lite." Still, as Eskridge and Spedale make clear, all the northern European countries have effectively legalized same-sex marriage. Most of them did not call it that for political reasons, but the intent was transparent.
Would legalizing same-sex marriage here lead to polygamy? Yes, I think, and even faster than in the Netherlands. Unlike the Dutch, we already have a sizable and militant underground polygamous movement. The ACLU is already on board to defend polygamy. The street demonstrations by polygamists have already begun.
Despite Eskridge and Spedale's happy talk, the Pandora's box that some fear gay marriage might open really does have some other scary items in it.