A standard conservative objection to the court permitting gay marriage is that if you allow that then you’ll have to allow polygamy as well. While I find both of these things distasteful, I find gay marriage far more so. Polygamy is presumed and at times considered good in the Bible and was common in many religious cultures. There are social problems with polygamy to be sure, but these would probably be smaller than critics claim. I have no reason to believe that monogamy is essential to our country as a commenter on Captains Quarters did and polygamy would be rare for obvious reasons. I don’t see it as a serious social issue. However the major impact of the Supreme Court saying this would be to lower the States in the Union to 49. Utah was forced to sign a treaty saying that they couldn’t allow polygamy in order to become a State. Although that has constitutional problems already (it sort of abridges the republican form of government requirement) the treaty would be obviously unconstitutional if the Supreme Court said polygamy was a constitutionally guaranteed right. In fact Utah would retroactively have never been a state and any law which passed by the margin of Utah’s votes would be void.
Unsurprisingly this issue will never be brought up, unless we have another 2000. The loser of the election might decide to gamble on that argument to the Supreme Court. Maybe not.