Federalism describes a division of power between state governments and a central government, and the relationship that subsists between them. Under a system of Federalism, in those areas in which the federal government can act, it is supreme. In all other areas, the state government or the individual is supreme. This division of supremacy is bound to lead to disagreements and tensions between the powers.
Federalism presents significant problems which include the shifting boundaries defining the areas in which Congress can or cannot act, as well as the potential for overlap in the separate areas of authority for the states and federal government. White the 10th Amendment is considered a key to Federalism, it does not necessarily address this particular issue. The 10th Amendment merely states that the boundaries between state and federal power are to be decided according to the powers enumerated in the Constitution, but it does not prescribe how broadly or narrowly the enumerated powers should be interpreted.
The practical limitations of Federalism can be seen in how education is regulated. Education is thought to be a matter of state and local control. However, the federal government has made clear that it is justified in affecting local education through its spending power and its power to regulate interstate commerce. Exactly where education and the spending power intersect, or how the spending power might yet be subject to containment, is unclear. That problem presents itself in many areas without a clear constitutional solution.
The most important change in the relationship between the states and the federal government since the Constitution’s adoption came in the wake of the Civil War with the passage of the 14th Amendment, the effects of which are wide ranging. The principle that runs through subsequent interpretations of the 14th Amendment is that the federal government can directly regulate states in areas that had been traditionally left to states. The 14th Amendment places limits on how states can structure their laws and treat their citizens. States cannot abridge the privileges and immunities of U.S. citizens; they must provide due process; and they must provide for the equal protection of the laws. These are structural limitations on state governments.
Though the limitations are consistent with liberty, they are a significant restructuring of the relationship between the federal government and the states. Since this amendment has been interpreted to mean that Congress can monitor the limitations placed on the states, and Congress is given the power to enforce the 14th Amendment’s limitations through Section 5, the result has been a dramatic shift of power to the federal government.