Insular Cases

The Insular Cases are a series of opinions by the U.S. Supreme Court in 1901, about the status of U.S. territories acquired in the Spanish–American War. The Supreme Court held that full constitutional protection of rights does not automatically (or ex proprio vigore—i.e., of its own force) extend to all places under American control. This meant that inhabitants of unincorporated territories such as Puerto Rico—"even if they are U.S. citizens"—may lack some constitutional rights (e.g., the right to remain part of the United States in case of de-annexation).

The Court also established the doctrine of territorial incorporation, under which the Constitution applied fully only in incorporated territories such as Alaska and Hawaii, whereas it applied only partially in the newly unincorporated Puerto Rico, Guam and the Philippines.

The term "insular" signifies that the territories were islands administered by the War Department's Bureau of Insular Affairs.

In 1898, the United States signed the Treaty of Paris (entered into force April 11, 1899), which ended the Spanish–American War and granted the United States the Philippines, Puerto Rico, and Guam. Additionally, Cuba remained under the jurisdiction of the United States Military Government until its independence on May 20, 1902. At the time, there was a debate on how to govern these new territories since nothing was said about it in the U.S. Constitution.

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