A number of commenters have asked about the relationship between law and marriage. Some, for example, have taken issue with the statement in my paper’s abstract that “marriage is primarily a creature of state law.” So I thought it was worth explaining a little but more about the relationship between state law and marriage.
Obviously, marriage is partly a private, non-governmental act. You can “marry” in the eyes of your religion or your community without ever marrying in the eyes of your state. Or you can have two separate marriage ceremonies — one religious and another one designed to satisfy the state’s requirements — which is what I did when I got married. In that sense, marriage is not just something the government makes up.
But the government also has a lot of rules which depend on whether or not you are married — being married affects your taxes, your health benefits as a federal employee, rights under an ERISA plan, child custody, your right not to testify, and so on. So even if you think the private, non-governmental part of marriage is more important than the government-recognized ceremony, the government still needs a way to figure out who is married and who isn’t. It generally uses state marriage ceremonies (or common-law marriage, now mostly of historical interest) to do so. Of course, you could also try to get rid of all laws that treat married couples differently from unmarried couples, but I no longer think that’s wise, and it’s certainly not going to happen any time soon.
So when I say that “marriage is primarily a creature of state law,” I really mean: “when the law deals with marriage, it’s mostly state law, not federal law, that determines marital validity.” You get a marriage license from the state where you’re getting married, not the federal government, and the state determines who can officiate, how old you have to be, whether you have adequately terminated any previous marriages you had, and so on. In that sense marital status is somewhat like property: federal law frequently turns on whether you have it, but it often uses state law to figure that out.
Finally, for purposes of this paper it doesn’t actually matter whether the federal government has the constitutional power choose to create its own independent marriage regime — with its own federal officiants, federal marriage licenses, etc. The main point is that it hasn’t created one. But I’ll also add that I think it would be impractical and unwise for the federal government to try to create such an independent marriage regime.