By invading and annexing Puerto Rico and other Spanish lands in 1898-1899, the United States took an imperial turn that unsettled its constitutional order. This dissertation traces responses by two groups—one within the U.S. government and another comprised of Puerto Ricans—to the legal uncertainty that reigned until Congress extended U.S. citizenship to "citizens of Porto Rico" in 1917. It also reconstructs the social and legal terrain surrounding key legal actions: the Treaty of Paris, the Foraker Act, the Insular Cases, and the Jones Act. For representatives of the U.S. government—federal judges, elected officials, and appointed administrators—U.S occupation of the island imposed hard choices between the exigencies of imperial governance and what they saw as adherence to constitutional norms. For a group of Puerto Ricans, mostly male politicians, competing federal actors and priorities provided openings to advance individual and collective claims to status.

This study traces the political and legal activities of officials and claimants as well as the metaphors they drew upon to explain their claims. U.S. officials characteristically expressed fidelity to legal concepts, alleged Anglo-Saxon superiority, and contrasted their actions with Spanish imperial misrule. Rather than reject racial hierarchies in U.S. imperialist and eugenic thought, Puerto Rican actors often claimed favorable positions within those hierarchies through Reconstruction metaphors and self-affirming historical accounts of their Spanish-era political participation.

Close study of Puerto Ricans who sought citizenship or self-government in this period, especially the unusual grouping of claimants involved in Gonzales v. Williams (1904), reveals that existing accounts of the Insular Cases overemphasize the coherence of these decisions. The oft-cited Downes v. Bidwell (1901), moreover, should be read alongside Gonzales. For two decades the Court declined to completely embrace the doctrinal innovations or delineate the implications for Puerto Rican rights of the Downes ruling. The Insular Cases developed slowly and ambiguously, transforming U.S. citizenship for Puerto Ricans from a status that courts might recognize in individual islanders and that might bring them full constitutional protections and eventual U.S. statehood, into a largely empty vessel, achievable only through Congress and heralding indefinite colonialism.