This book combines a detailed examination of the history of the Supremacy Clause with a comprehensive consideration of all aspects of Supremacy Clause Doctrine. It explores how the Supremacy Clause makes federal law the supreme Law of the Land, so that federal law overrides conflicting state law. This work also looks at how the Supreme Court frequently requires not supremacy but equality when applying the Supremacy Clause by invalidating state laws that discriminate against the federal government. This volume gives a detailed history of the Supremacy Clause by tracing the origins of federal supremacy from colonial days. It gives particular attention to the evolution of the Supremacy Clause in the Constitutional Convention and discussions of the Clause during the ratification debates. Foundational decisions of the Supreme Court interpreting the Clause are discussed as well as the role of the Clause during critical confrontations between states and federal government. This work also considers in detail the doctrinal role of the Supremacy Clause today by discussing contemporary topics and recent controversies surrounding them.