The Insular Cases are a series of U.S. Supreme Court decisions from the early 1900s that addressed the status of territories acquired by the United States, such as Puerto Rico and Guam, following the Spanish-American War. These cases determined whether the constitutional rights of U.S. citizens applied to residents of these territories. The rulings established that not all constitutional rights automatically extend to these territories, leading to the concept of "unincorporated territories." This means that while some constitutional protections apply, others do not, creating a unique legal status for these regions within the United States.