Events that changes relationship between federal and state government?

However, the relationship between the national government and state governments is not rigid, federalism has changed greatly over the years and continues to evolve and grow as new events and issues come to affect the country. The United States has experienced multiple forms of federalism that seemed best fit for the country at the time of their formation. It is important to mention that a major factor that affects the development and change of federalism are the rulings of the United States Supreme Court. This is because, although the Constitution established a federal system of government, the method of dispersing power between the states and national government is unclear in the document. For this reason, the Supreme Court has become prominent in defining the nature of the federal system.