In America, Federalism continues to be interpreted in numerous ways, tipping the balance between the national and state governments.
The Due Process and Equal Protection Clauses of the Fourteenth Amendment give the national government the power to enforce protections for any person against the states. The Supreme Court determines the extent of these protections.
The Commerce Clause, on the other hand, gives the national government the power to regulate interstate commerce. In United States v. Lopez (a required court case!!!), we see how this power isn’t absolute. Long story short, the Court ruled that guns were not part of interstate commerce and therefore the national government couldn’t regulate them in the context of the case.
Another required case, McCulloch v. Maryland, is in relation to the Necessary and Proper Clause and the Supremacy Clause. The Supremacy Clause states that national laws take power over state laws, and the Necessary and Proper Clause states that the national government can use implied powers to carry out the enumerated (stated) powers of the Constitution.