The decay of Dual Federalism is directly due to the unchecked expansion of the National government. The assumption that problems are so big that only a big government can solve them places cart before horse -- we have an ever-expanding federal government that actually creates huge problems to justify its existence rather than solves them. The reason the the federal government has mushroomed unchecked since the New Deal is precisely because of the Constitutional violations that occurred then, and which continue until today. Certainly it is the function of the national government to provide defense when invaded -- however, the endless government programs in place that should not exist by Constitutional standards create cultural inefficiencies that cannot be countered -- hence the big problems. The federal government should not do for the states what the state government should do for itself. State government should not do for people what people should do for themselves. "Government governs best that governs least."
Basically, dual federalism has eroded over the years. The main thing that drives this decline of dual federalism is the occurence of crises. In other words, whenever there is a crisis, the federal government takes more power for itself. Some of the most important crises that caused the federal government to take more power are:
- Civil War
- World War I
- Great Depression (this is a very major factor)
- World War II
- Cold War (to some extent)
- 9/11 -- mostly in terms of security
When a crisis occurs, people demand action. The main focus of these demands tends to be the national government because it is more visible. So the national government responds to the people's demand for solutions.
Also, the problems that lead to the crises (and their solutions) tend to be too big for any one state. Therefore, the national government has to be the one to try to fix things.
These reasons explain why crises lead to more power for the national government and less dual federalism.
Before the national government began to assume a position of dominance, the American system leaned toward dual federalism, a system under which states and the national government each remain supreme within their own spheres. The analogy of layer cake federalism is often used to describe dual federalism because the powers and policy assignments of the layers of government are distinct (as in a layer cake), and proponents of dual federalism believe that the powers of the national government should be interpreted narrowly.
The national government took a direct interest in economic affairs from the very founding of the republic. As the United States changed from an agricultural to an industrial nation, new problems arose and with them new demands for governmental action. The United States moved from a system of dual federalism to one of cooperative federalism, in which the national and state governments share responsibility for public policies. Using the analogy of marble cake federalism, American federalism is portrayed as a system with mingled responsibilities and blurred distinctions between the levels of government. Cooperative federalism—which may be seen as a partnership between the national and state governments—began in earnest with the transformation of public attitudes toward the role of the national government during the Great Depression of the 1930s. For hundreds of programs, cooperative federalism involves shared costs, federal guidelines, and shared administration.