Final answer:
The supremacy clause in Article VI of the U.S. Constitution ensures that states cannot use their reserved or concurrent powers to override national policies. The Tenth Amendment outlines the reserved powers of the states, while Article I, Section 10 of the Constitution specifies powers denied to states to prevent undermining federal authority.
Step-by-step explanation:
The U.S. Constitution's supremacy clause means that states cannot use their reserved or concurrent powers to counter national policies. The supremacy clause is found in Article VI of the Constitution, which establishes that federal law is superior to state laws. Additionally, the Tenth Amendment is significant in defining the balance of power between the national government and the states. It states that '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.' These reserved powers provide the states with authority over matters not explicitly controlled by the federal government, while the supremacy clause ensures that state power does not undermine federal authority.
To prevent conflicts between state and national laws, certain powers are specifically denied to states, such as coining money or entering into treaties, as outlined by Article I, Section 10 of the Constitution. Shared powers or concurrent powers, on the other hand, can be exercised by both the state and national governments because the Constitution does not exclusively allocate these powers to the national level. An example of a concurrent power is the ability to levy and collect taxes, which both state governments and the national government have the right to do.