Final answer:
States can have different laws dealing with certain issues as long as they do not violate principles set out in the constitution. The Supremacy Clause in Article VI establishes that the Constitution and federal law are the supreme law of the land.
Step-by-step explanation:
States can have different laws dealing with certain issues as long as they do not violate principles set out in the constitution. The Constitution grants certain powers to the federal government and reserves the rest to the states. However, the Supremacy Clause in Article VI establishes that the Constitution and federal law are the supreme law of the land, meaning that if a state law conflicts with a federal law within the national government's constitutional authority, the federal law must prevail.