1-13. Army leaders directing DSCA missions or tasks must understand how the Constitution of the United States structures the powers of the federal government and limits the powers of military forces operating in the homeland. They must understand how national and military policy applies constitutional principles. The Constitution divides state and federal forces and establishes the fundamental precept that the military serves in support of civil authority. Consistent with this precept, preparedness policy structures DSCA to ensure unity of effort. The 10th Amendment to the U.S. Constitution, “the powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people,” provides the legal authority for the division of state and federal forces and limits federal police powers and serves as a foundation for national DSCA authorities.