In 1898, following a conflict with Spain that Secretary of State John Hay famously dubbed a “splendid little war,” the United States radically transformed its borders and its global identity,. Through the Treaty of Paris, a defeated Spain ceded the Philippines, Puerto Rico, and Guam to the U.S. for $20 million,. Seizing the momentum of empire fever, the U.S. also annexed the independent nation of Hawaii, as well as Wake Island and American Samoa,,. By the time the treaties were ratified, the United States had assembled an overseas empire comprising more than seven thousand islands and 8.5 million people.
This sudden expansion birthed the “Greater United States,” but it also posed a profound ideological and demographic dilemma,. Throughout the 19th century, when the U.S. expanded westward or seized vast tracts of land from Mexico, it deliberately avoided incorporating heavily populated areas to prevent absorbing large populations of non-white peoples,. Spain’s former colonies, however, were densely populated. This reality forced the nation to confront a fundamental trilemma: the United States could not simultaneously uphold its core traditions of republicanism, maintain white supremacy, and manage an overseas empire.
The conflict over how to govern these new subjects culminated in 1901 in a series of landmark Supreme Court decisions known as the Insular Cases,. The legal disputes themselves seemed entirely mundane—involving questions like whether an importer had to pay tariffs on oranges shipped from Puerto Rico to New York, or if a soldier owed taxes on diamond rings brought back from the Philippines. But beneath these disputes lay an existential constitutional question: Did the Constitution follow the flag? Were the territories fully part of the United States, and were their inhabitants protected by the U.S. Constitution,?
The U.S. attorney general argued forcefully that the federal government had to be able to rule its new possessions as colonies. He insisted that the Constitution applied strictly to the states, warning the Court that the inhabitants of the new territories were subjects, not citizens, and that Congress could impose laws “without asking the consent of the inhabitants, even against their consent”. “A great world power,” the government argued, “must not be bound by rules too strict or too confining”.
The Supreme Court agreed, delivering a ruling that fundamentally rewired American law. The Court invented a novel legal distinction between “incorporated” territories (those intended for eventual statehood, which received full constitutional protections) and “unincorporated” territories (the newly acquired overseas colonies). The Court ruled that the Constitution did not automatically apply in full to these unincorporated territories. In a famously convoluted concurring opinion, Justice Edward White declared that Puerto Rico was “foreign to the United States in a domestic sense” because it was “merely appurtenant thereto as a possession”.
The Insular Cases were deeply infected by the racial prejudices of the era. Tellingly, eight of the nine justices who decided the 1901 Insular Cases were the exact same men who had codified the “separate but equal” doctrine of Jim Crow in the infamous 1896 Plessy v. Ferguson decision. Just as Plessy permitted spatial segregation by race, the Insular Cases segregated the Constitution itself, effectively splitting the U.S. into “practically two national governments”—one bound by the Bill of Rights and one that was not. The justices explicitly warned that extending constitutional rights to “savages” and “alien races” could “wreck our institutions” and overthrow the government.
Chief Justice Melville Fuller, dissenting from the majority, warned that this framework left the colonies like a “disembodied shade, in an intermediate state of ambiguous existence for an indefinite period”. He was entirely correct, and that “indefinite period” continues to this day. While Plessy was eventually overturned, the Insular Cases remain on the books as good law. They established a permanent legal architecture for American imperialism, ensuring that millions of colonized subjects could be governed under U.S. rule without the guarantee of democratic representation, full constitutional rights, or Fourteenth Amendment birthright citizenship.