Not long ago, the prohibition of same-sex marriage, like the prohibition of interracial marriage before it, was so deeply ingrained in our social fabric and legal understandings that the recent turnabout by the New York State Legislature might have seemed unimaginable. As recently as 1986, the United States Supreme Court rejected a gay man’s argument for constitutional protection of his sexual relationship, declaring the argument as “at best, facetious.” In 2001, the court overturned that ruling and accorded same-sex partners the same constitutional protection as heterosexuals. Same-sex marriage may soon become legal in even more states.
What now of the two remaining criminal prohibitions of intimate relationships: incest and polygamy? Even as same sex and interracial relationships are accepted, Americans are now imprisoned for incest or polygamy.
The cases against polygamy and incest are not nearly as strong as most people imagine. Yet they will not become legal anytime soon. To see why, it helps to understand the evolution of moral assessments of interracial and same-sex marriage.