One of the common arguments against gay marriage was the slippery slope argument. If we allow gay marriage, the next stop is surely polygamy, to be followed by cats and dogs living together, people marrying their toasters, and so forth. The recent attempt by Nathan Collier of Montana to get a marriage license for a second contemporaneous marriage (inspired by the Roberts dissent in the SCOTUS decision) seems to point to an imminent fulfillment of this fear, that polygamy will follow hot in the steps of gay marriage and become legalized.
This is of course a big topic, but I would like to make just two points to suggest people don’t need to move into their backyard shelters in anticipation of an immediate Apocalypse.
First, the vast majority of polygamists have no interest in legalization and certainly are not stumping for such a thing. The Montana attempt is an outlier. Polygamist “marriages” do not involve multiple marriages sanctioned by the state. Rather, only the first marriage is recognized by the state; subsequent marriages are privately treated as such by the family involved and its supporters, but there is no color of legal sanction to those relationships. The vast majority of polygamists simply want decriminalization of polygamy, which is a very different thing from legalization. The Utah Brown decision, if upheld on appeal, is the only kind of legal protection most polygamists are after.
Second, legalizing polygamy is not something that could be effectively done with a single court decision. Once we gave up coverture, marriage in our law became essentially blind as to gender in its particulars (other than the question of who may enter the state in the first place). Now that gay marriage is lawful, our family law does not need a huge overhaul to accommodate it, as it is still a binary between two people only.
Legalizing polygamy would not be anywhere near so simple. It would require an extensive reworking of our law in many areas in order to be workable. Will these be treated as one group marriage (rather like a business association, which would then be governed by a board of some sort), or a series of (nonexclusive) binary marriage contracts? With multiple legal spouses, what do we do about insurance benefits? Who gets to make medical decisions? Child custody issues? Does a polygamous spouse get the immigration benefits of marriage? Which spouse gets social security benefits, or do you allocate them pro rata among all spouses or something like that? How would intestacy work? The practical challenges to legalizing polygamy would be legion.
These legal challenges could be solved by motivated legislatures committed to solving them. After all, writing laws is what they do, and certainly creative solutions to these kinds of conundrums could be found. But in the absence of a substantial constituency backed by public opinion stumping for such legal marital structures, it just ain’t gonna happen.