Readers of Justice Kennedy’s opinions in Lawrence v. Texas (2004) and United States v. Windsor (2013) will find many familiar notes in the language of Obergefell’s majority decision. “Dignity” (9 times) and “liberty” (24 times) are paramount, as before, and the opinion emphasizes how exclusion from marriage “disparages” or “demeans” gays and lesbians. What strikes a new key is Kennedy’s emphasis on the balance between timelessness and innovation in institutions central to our society.

At oral argument, Kennedy had worried some supporters of same-sex marriage by referring to how “the word that keeps coming back to me in this case is—is millennia, plus time.” Some thought that might mean that Kennedy would be loath to change a definition of marriage that had endured for millennia.

Instead, his Obergefell opinion suggests that Kennedy has become a common law constitutionalist, believing that the immemoriality of particular legal institutions, such as marriage, does not prevent them from changing over time. He refers specifically to the very significant alteration in marriage rendered by shifts in the status of women, as well as the rapid change in public sentiment about the desirability of same-sex marriage.

This means that, on the one hand, Kennedy stresses the timeless tradition of marriage—and emphasizes as one the principles he derives from precedent that “marriage is a keystone of our social order,” an observation connecting back even to the Court’s decisions in the nineteenth century rejecting Mormon polygamy. On the other hand, he takes up the more expansive vision of substantive due process protection of fundamental rights advanced by Justice Harlan’s dissent in Poe v. Ullman (1961) rather than the narrower understanding represented by cases like Washington v. Glucksberg (1997). It is, indeed, against this conception of substantive due process that Chief Justice Roberts inveighs most vigorously in dissent. This double emphasis in Kennedy’s opinion—on tradition and innovation—suggest that living constitutionalism à la David Strauss’s description in The Living Constitution is, in fact, alive and well.