Have Justices Stevens and Kennedy Forged a New Doctrine of Substantive Due Process?

As issues such as the nature of the sexual, marital, and other relationships and claims—both personal and economic—continue to face Americans and America’s lawyers, the question of how we as a people distinguish fundamental from non-fundamental rights is one of first importance. In constitutional law, the Supreme Court has addressed this question through the doctrine of “Substantive Due Process.” In his lengthy dissent in McDonald v. Chicago—his final opinion as a Supreme Court Justice—Justice John Paul Stevens claimed that substantive due process is fundamentally a matter of how we interpret the meaning of the word “liberty.” The issue as to whether the right is specifically enumerated in the Amendments is irrelevant, Stevens argues, if the interest is naturally within the definition of “liberty.” Moreover, Justice Stevens’s argument in McDonald was approved by his liberal colleagues on the Court, which indicates that his theory of liberty may well become the baseline for determining what are, and what are not, fundamental rights. However, in the recent case of United States v. Windsor, the Court refused to employ the substantive due process doctrine, as traditionally understood, as the basis for striking down the Defense of Marriage Act (DOMA). Instead, the Court employed rational basis review, finding that the legislative purpose and effect behind DOMA was “to disparage and to injure” those wishing to enter into same-sex marriages, and thus served “no legitimate purpose.” Still, Justice Kennedy clearly signals in his Windsor opinion that some formulation of the substantive due process doctrine remains alive and well as a constitutional basis for deciding Fifth and Fourteenth Amendment Due Process “liberty” interests such as same-sex marriage. Indeed, both Justices share a conceptual core in their understandings of what constitutes a constitutionally protected liberty interest.