An old argument has resurfaced lately on two blogs that I read, namely that accepting the arguments for constitutional protection of same-sex marriage also forces the conclusion that polygamous marriage is constitutional guaranteed. The first is Robert George, in a characteristic screed that seems devoid of any interest in actual discourse:
Now, the reason of principle that intimate partnerships of three or more persons cannot truly be marriages, and should not be legally recognized as marriages or the equivalent, is . . . Well, remind me again, what is it?The second is Josh Blackman, in a more tempered and inquisitive post:
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But what is the reason of principle that can be given by those who, while rejecting the idea that sexual-reproductive complementarity is an essential element of marriage, do not---or do not yet---wish to jettison the idea of marriage as the sexually exclusive union of two, and not more than two, persons? Is there a reason of principle? Or is the belief in "two-ness" mere bigotry?
I don’t see much of a difference between the arguments, from a constitutional perspective, in favor of SSM and arguments in favor of polygamy. I think they are equally valid. If we are not going to base marriage on traditional notions, why stop at a couple of the same sex. Why not a trio of the same sex? I think the key distinction is that the former cause has a very strong social movement with a lot of popular support. The latter does not.As I've argued before, the arguments in support of same-sex marriage and polygamy are easily distinguishable. The marriage equality movement, contra those like George, does not rest just on a "conception of marriage as sexual-romantic domestic partnership." It also looks at the legal meaning of marriage, as defined by the benefits which the government gives to married couples.
Many of those benefits would not make sense in a polygamous system, meaning that legal recognition of polygamous marriages would involve fundamentally changing the institution of marriage (the legal institution, not the hypothetical, quasi-religious "institution" that religious conservatives try to will into existence), as opposed to extending an already-extant institution to new individuals who are currently denied access.
Before going into exactly how marriage would have to change to accommodate polygamous relationships, let's distinguish two different kinds of polygamy. The first is what I'll call Polygamy 1, which involves multiple overlapping two-person marital relationships. In other words, A is married to B, and B is also married to C. A and C, however, are not married. The other (Polygamy 2) involves genuine multiple-person marriage, where A, B, and C are married. Some of the issues will apply equally to Polygamy 1 and 2, but sometimes the distinction will be important.
Inheritance
One important legal aspect of marriage is its impact on inheritance. Generally speaking, if someone dies without a will and without children, their surviving spouse inherits all of their property. Even if they have children, the surviving spouse generally receives the largest share. There are somewhat obvious ways to change these rules to fit a polygamous system, but they do require changes. More difficult to deal with is the fact that the surviving spouse is generally put in charge of the estate. If there are multiple surviving spouses, there is no obvious way to choose between them.
Marriage also generally provides exemptions from estate taxes. Either form of polygamy would drastically increase the risk of marriage being used for estate tax fraud.
Taxes
Our tax system is premised on the idea that it makes sense for two individuals who are married to file taxes jointly. Polygamy 1 poses a bigger issue here: if A and B are married, and B and C are married, with whom does B file their tax return? All of the options (a three-way tax return, two joint tax returns, three individual tax returns) have issues, and all of them would require a substantive overhaul of the tax system to implement. Polygamy 2 also has issues, though. Even if the three-way tax return is clearly the right choice, it still requires an overhaul of how we handle taxation. This is all not to mention, of course, the increased risk of tax fraud.
Medical Decision Making
Generally speaking, the spouse has priority in making health decisions when the patient is unable to and hasn't made an explicit designation of a health care surrogate. Both forms of polygamy would undermine this important clarity.
Employment Benefits
The government and other employers usually give spousal benefits. Either form of polygamy would increase the risk of fraud as well as raising costs and giving unfair extra benefits (or unfair lower benefits) to those in polygamous marriages.
Divorce
Polygamy 2 presents lots of issues for divorce. Assuming our A-B-C marriage, say A wants to divorce C. That forces B to choose between A and C, causing new issues which our current divorce system does not need to face. Now say that there are children of the A-B-C marriage. Biologically they are the children of B and C, but all three are treated as parents. If B remains with C after the divorce, do they have sole right to custody? Do they have a right to "2/3" custody? Should custody be split evenly between A and between the B-C marriage? If B and C later divorce, can that divorce change the custody rights of A?
What about asset splitting? If B chooses to remain with C after a divorce caused by friction between A and C, is B also responsible for alimony and child support to A, or does that liability rest only with C? Or, if the assets run the other way, do we calculate the alimony that A must pay with respect to only C, or with respect to both B and C? All of these issues become more and more complex the more partners you add to the marriage.
Polygamy 1 also presents some issues. If we have A-B and B-C marriages, and A and B divorce, how do we divide assets? Assume we're going for an "even split" in the two-person marriage sense. Do we require that each marriage have its own separate assets the entire time, and then split the A-B assets upon divorce? That would leave B in a precarious spot, while both marriages were ongoing, of trying to balance two very separate asset pools. Or do we exclude the assets brought by C and split the assets brought by A and B? That would effectively be stealing from C: if C later divorced B, C would only get half as much of B's money as A did. Once again, there doesn't seem to be an easy answer, and adding more and more partners just makes it more difficult.
Children
While we might be able to pretty easily work out parenting and child-raising in Polygamy 2, there are issues with Polygamy 1. Suppose we have our A-B and B-C marriages, and that B is a woman and A and C are men. If B has a child, who becomes its other parent by default? In the current system, we assume that a child born in a marriage is the child of both parties to the marriage until legal proceedings determine otherwise. But in the case of Polygamy 1, there's no logical default answer. We're stuck having paternity tests and legal proceedings with every birth.
I'm sure there are other ways in which polygamy would require a drastic reshaping of the legal rights and responsibilities of marriage, but I think the above illustrates the point. Where same-sex marriage simply requires opening the doors to people previously excluded, polygamous marriage, in either form, would fundamentally change what law considers marriage to be. Same-sex marriage, then, does not lead inevitably to polygamy.
(I owe thanks to Michael Yuri, a commenter on the Josh Blackman blog post linked above, for raising some of the issues I discuss above. The exact positions and any errors or failings are, of course, mine.)