Final answer:
The necessary and proper clause and the Tenth Amendment outline the powers of the federal government and the states, respectively, leading to a balance-of-power conflict with the Supreme Court often defining the boundaries.
Step-by-step explanation:
The conflict between the states and the national government regarding the necessary and proper clause and the Tenth Amendment centers on the balance of power. The necessary and proper clause, also known as the elastic clause, grants Congress the power to enact laws that are deemed necessary and proper to exercise its enumerated powers. This has allowed the federal government to assume broader powers over time, especially in regulating economic activity through the commerce clause. However, the Tenth Amendment asserts that powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states or the people. Over the years, the U.S. Supreme Court has interpreted these provisions to delineate the extent of federal and state authority, sometimes restricting Congress's reach in areas traditionally managed by the states, like education and local law enforcement.