Puerto Rico may have its own constitution, elect its own leaders, and pass its own laws, but when it comes down to it, Congress, not the people of Puerto Rico, is the ultimate source of the island government's power. That's the lesson from today's Supreme Court ruling in Puerto Rico v. Sanchez Valle, over whether the Commonwealth of Puerto Rico could prosecute criminals already tried by the federal government, as the 50 states can.
Under the dual-sovereignty doctrine, both federal and state governments may prosecute an individual for a crime, so long as they do so under their own laws. Puerto Rico argued that it was entitled to the same rights as the states when it came to double jeopardy. But, while acknowledging Puerto Rico's "distinctive, indeed exceptional status," the Court ultimately determined that Puerto Rico's prosecutorial power comes from the U.S. Congress, rejecting the island's claim to state-like sovereignty. The ruling is a blow to the island, and it may soon be followed by more Supreme Court losses in the near future.