On January 13th, 2016, the Supreme Court of the United States heard oral arguments in Puerto Rico v. Sanchez Valle. The question that the Court must decide is whether the federal government and the Commonwealth of Puerto Rico are separate sovereigns for purposes of the Double Jeopardy Clause. This essay argues that the Supreme Court cannot answer this question in the affirmative without overturning precedent holding that the U.S. government can unilaterally impose the Federal Death Penalty Act in Puerto Rico. In other words, the Court cannot deprive Puerto Rican citizens of the protection of the Double Jeopardy Clause unless it adopts the concept of popular sovereignty.