In fact, it may be more likely that a completely different part of the Fourteenth Amendment will end up being invoked to secure a constitutionally protected right to gay marriage. The due process clause says that states may not deprive persons of life, liberty, or property without due process of law. And over the past century, the Supreme Court has spent a great deal of time itemizing the specific liberties protected by this guarantee. Among these, the Court has included a series of guarantees regarding marriage. Most importantly, in Loving v. Virginia (1967) the Court held that states could not ban interracial marriage since "the freedom to marry has long been recognized as one of the vital personal rights essential to the orderly pursuit of happiness by free men." To "deny this fundamental freedom on so unsupportable a basis as racial classifications," Chief Justice Earl Warren wrote, was "directly subversive of the principle of equality at the heart of the Fourteenth Amendment." In short, "under our Constitution, the freedom to marry, or not marry, a person of another race resides with the individual, and cannot be infringed by the State."44
Beyond this explicit guarantee regarding interracial marriage, the Court has been building a more extensive zone of privacy around marriage since the 1920s. Today, that zone includes a guarantee that personal questions—such as who to marry, whether to have children, whether to use contraception, whether to terminate a pregnancy, or how to raise and educate children—are left largely inviolable by government action.
It may be that the incorporation of an unqualified right to decide who to marry as a liberty guaranteed under the due process clause may be the shortest route to a constitutional protection for gay marriage.
Some think that the Court hinted as much in its 2003 decision in Lawrence v. Texas. In striking down the state's "Homosexual Conduct" law, the Court relied primarily on the rational basis test; it could find "no legitimate state interest" in this law so directly impacting one classification of people. But in the fine print, the decision referenced a more fundamental right to privacy and marriage established in earlier abortion cases. Writing for the majority, Justice Anthony Kennedy cited Planned Parenthood v. Casey and its affirmation of a "constitutional protection to personal decisions relating to marriage, procreation, contraception, family relationships, child rearing, and education." He dwelled on the precedent long enough to explore the more abstract elements within this protection:
"These matters, involving the most intimate and personal choices a person may make in a lifetime, choices central to personal dignity and autonomy, are central to the liberty protected by the Fourteenth Amendment. At the heart of liberty is the right to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life. Beliefs about these matters could not define the attributes of personhood were they formed under compulsion of the State."
Justice Kennedy closed by noting that, "persons in a homosexual relationship may seek autonomy for these purposes, just as heterosexuals do."45
In short, while the equal protection clause of the Fourteenth Amendment might seem, on the surface, to be the most logical path to a constitutional right to gay marriage, and while equal protection clauses within the state constitutions of Massachusetts, Connecticut, and Iowa have served to establish the right in these states, the due process clause may prove the more likely avenue to a constitutional right at the national level. Then again, shifting political currents may generate a more direct political route to the legalization of gay marriage in the future. Recent surveys show that young people are far more likely to support gay marriage than older people. Perhaps as significant, 40% of the public now can identify a close friend or family member who is gay. Ten years ago, only 20% of the public could say the same.46
They say that familiarity breeds contempt. In this case, the opposite may be true. If so, gay marriage advocates may not have to depend upon the Supreme Court to move in a direction it has thus far not been prepared to go, imposing a right to gay marriage by judicial ruling. Instead, the Court may be able to assume the more comfortable role of providing constitutional affirmation for an already shifting public consensus.