The purpose of the 10th Amendment has been a controversial issue since the founding of America’s constitution. Of all the foundations implemented into the Bill of Rights and the Constitution since America’s founding, the issues which continue to surround the Tenth Amendment have stemmed from the conflicting interpretations of both the court and politicians at different points in time. In fact, they remain at the heart of the most controversial debates to date. Furthermore, the tenth amendment, which states, “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people,”[1] is meant to protect each of these powers from both entities. Those powers not delegated are reserved. It says nothing about whether delegated powers are to be broadly or strictly construed. In retrospect, the most significant differences in constitutional law are a direct result of the U.S. Supreme Court’s revival of federalism as a constraint on federal power. The federalism decisions, which will be discussed in detail, are the product of the Rehnquist Court. With a majority comprised of five conservative SCOTUS justices under the leadership of William Rehnquist who were all deeply committed to protecting state rights from federal government invasion. Justices Scalia, Kennedy, Thomas, and O’Connor, were responsible for introducing the concept of “New Federalism,” which virtually affected every area of U.S law, both civil and criminal, which ultimately changed the course of history and the future of the Supreme Court. The Court’s rulings are also pledged with restoring what the founders had in mind when they composed the tenth amendment. Among them, to restore dual sovereignty between government entities, establish an effective and fair system of centralized power, and overall, protecting the virtues that come with the promise of individual liberty. Thus, the goal of this report is to address and evaluate past Supreme court cases and specific provisions that were both relevant to the reconstruction of the Tenth Amendment as a limit on the powers of Congress, and were resolved by the Rehnquist Court. It will also provide an analysis to express the data and briefings which are fundamental to each court case, and thus significant to the evolution of constitutional law. Another area that requires further analyzation concerns the doctrine of sovereign immunity. Therefore, an analysis over the significant role that the Rehnquist Court played in the expansion of sovereign immunity is essential to understanding this part of the discussion.