This Note evaluates the effects of United States v. Windsor on the legitimacy of moral justifications for legislation by examining the hypothetical case of polygamous prospective immigrants. Coupled with Lawrence v. Texas, its predecessor in reasoning,and now Obergefell v. Hodges, its natural extension, Windsor signals the Supreme Court’s willingness to strike legislation motivated by impermissible moral justifications. The Court neither defines the moral arguments to which it is opposed, however, nor specifies whether moral justification remains permissible in some legislative contexts. Recent instances of polygamous spouses seeking admission to the United States provide the foundation fora strong test case for the lingering viability of legislated morality. The polygamy bans contained in state public policy and federal immigration law originated in legislatures motivated in part by religious and other types of moral reasoning, at least some of which offends modern sensibilities. If the current Supreme Court were to hear an equal protection or substantive due process challenge to these bans, recent precedent suggests that the Court would apply heightened scrutiny based on a finding of apparent animus or a deeply rooted tradition, respectively. In response, the federal government could justify the continued existence of the polygamy bans in part on non-moral reasoning. Nevertheless, the legacy of their passage and the ongoing moral opprobrium of many Americans towards polygamy suggest that a Court adhering to its Windsor precedent would invalidate these bans for a violation of equal protection. The implicit dependence of the Windsor and Lawrence Courts on the “emergent rights” of a minority has little parallel for polygamists, however, militating against any near-term decision in their favor, although not dispelling concerns that the Court has narrowed the historic role of religious and other moral justifications for legislation.