You've had your eye on that cute alien for a while now. You've gone on some dates, really hit it off, and you're thinking you'd like to pop the question. But even if your extraterrestrial beau or belle says "Yes," would the US government recognize your union?
The fine legal geeks at Law and Multiverse placed this question under consideration. Would the US government let you marry the djinn or alien of your dreams? Unfortunately, probably not. Marriage in the US is determined by individual states, but it's helpful to look to the federal definition of personhood when determining the meanings of terms like "man," "woman," and "person" in state marriage statutes:
At the federal level, 1 U.S.C. § 8 defines "person" to include "every infant member of the species homo sapiens who is born alive at any stage of development." This is an inclusive rather than exclusive definition (and it's not specifically about marriage), but it underscores the point that only humans are people. The federal Defense of Marriage Act provides (for now) that "the word ‘marriage' means only a legal union between one man and one woman as husband and wife, and the word ‘spouse' refers only to a person of the opposite sex who is a husband or a wife." Combined with 1 U.S.C. § 8 and the plain meaning of the words, federal law also appears to only contemplate marriage between humans.
James Daily at Law and the Multiverse has a longer analysis of this issue, including whether granting personhood to aliens and supernatural beings would necessarily make this kind of intermarriage legal.
However, how does this definition come into play when we're talking about zombies and vampires? After all, the human undead were born alive, and posthumous marriage is not a completely unheard of practice. France has a statute on the books that allows for posthumous marriage under certain conditions, and there's at least one case of a marriage license being signed in the US after the groom had died. Of course, Daily notes that all of this only matters if the government knows that one of the parties is a non-human, so perhaps your best bet for legal matrimony is to simply keep quiet about your partner's alien status, if that's an option.
Marriage and the Multiverse [Law and the Multiverse]