How can state and federal governments sometimes bring separate cases involving the same conduct?

Under the Fifth Amendment to the U.S. Constitution, the double jeopardy clause protects individuals from being prosecuted or punished twice for the same offense by the same sovereign. However, this protection does not extend to separate prosecutions by different sovereigns, such as state and federal governments.12

Because the United States operates under a system of dual sovereignty, both the federal government and individual states possess the authority to enact and enforce their own laws. Consequently, if a single act violates the laws of both jurisdictions, each sovereign may independently prosecute the individual for that conduct without violating the Fifth Amendment. While some states have enacted their own laws to prohibit state-level prosecution following a federal trial for the same conduct, the U.S. Supreme Court has affirmed that the federal Constitution does not forbid these multiple prosecutions by separate sovereigns.12