From a strictly legal perspective, therefore, the court’s decision in Obergefell contains arguments and dicta that could be used to make the case for or against robot-human marriage. Of course, as a practical matter, the legal legitimacy of robot-human marriage is not going to be recognized anytime soon. Most people (including judges) presumably think robot-human relationships are absurd and twisted. But that was once also the case for interracial marriage and same-sex marriage. Of course those advances involved sanctioning the love and relationship of two human beings, regardless of their race or sexual preferences, which is arguably quite distinct from recognizing human-machine marriage. But as robots become more and more humanlike in their appearance and behavior, this distinction may eventually erode away.
The Supreme Court itself recounted the long, difficult road to get to the point where the law (and most of society) could now recognize same-sex marriage. First, advocates had to overcome the classification of same-sex relations as an illness. Then they had to declassify it as a crime. And then finally—after countless referenda, legislative debates, grass-roots campaigns, studies, popular and scholarly writings, and lawsuits—the right to marry people of the same sex was finally legally recognized.
The path to recognition of robot-human marriage is likely to be equally, if not more, lengthy, torturous, and contested. But as the court emphasized at the close of its opinion in Obergefell, the issue comes down to the “fundamental right” of a person in a free society to choose the nature of the relationships and lifestyle they choose to pursue, providing they do not unreasonably harm others in exercising their choices.