This chapter examines the Supreme Court’s practice, over approximately a century and a half, in developing and applying the “substantive due process” doctrine. The animating premise of that doctrine is that the Due Process Clause confers judicially enforceable protections against substantively unfair infringements of certain “unenumerated” yet fundamental or important rights. After the Court’s embarrassed climb down during the 1930s from a line of decisions enforcing rights to freedom of contract, the Court reembraced the Due Process Clause as a source of “unenumerated” rights in Roe v. Wade (1973) and, later, in decisions protecting rights to engage in private acts of sexual intimacy and extending the unenumerated right to marry to same-sex couples. Although the current Court overturned Roe in Dobbs v. Jackson Women’s Health Organization (2022), the majority opinion avoided a strictly originalist approach by embracing precedents holding that the Due Process Clause protects some fundamental substantive rights that are grounded in “tradition.” The chapter explores the conservative justices’ reasons for adopting that position. It also considers whether substantive due process decisions invalidating prohibitions against sodomy and laws defining marriage as necessarily involving one man and one woman can survive under the rationale of Dobbs.

This chapter examines the Supreme Court’s historically evolving interpretation of the Equal Protection Clause, including its recent embrace of the view – initially uttered by a solitary dissenter in an 1896 decision in the case of Plessy v. Ferguson – that “[o]ur Constitution is color-blind.” In equal protection cases, the Court has rarely claimed originalist support for its decisions, even when effecting sharp changes of course, as in its iconic decision in Brown v. Board of Education (1954). In a recurring pattern, the Court’s leading equal protection decisions have condemned forms of discrimination –– first on the basis of race, then sex, and then sexual orientation –– only when public opinion began to view them as unjustifiably bigoted. This chapter analyzes the Court’s recent decision to invalidate practices of affirmative action in higher education that prior decisions had permitted for more than forty years. It also surveys a branch of equal protection doctrine that strictly scrutinizes deprivations of rights that the Court deems “fundamental” under the Equal Protection Clause, centrally including voting rights. It explains continuities, but also revealing disparities, between the approaches to voting rights of the liberal Warren Court, on the one hand, and the conservative modern Court, on the other.

The chapter discusses several cases further setting the Court against the tenor of the New Deal, including its invalidation of the Agricultural Adjustment Act in United States v. Butler.