The Tenth Amendment was cited for support by the Court in its 2013 decision invalidating a key portion of the Voting Rights Act, Shelby County v Holder. In its 5 to 4 decision invalidating the Act's coverage formula, which required a group of mostly southern states to seek preclearance from the federal government for changes in their voting laws, the Court noted that the Tenth Amendment was intended to give states "broad autonomy in pursuing legislative objectives." Mostly, however, the decision rested on the principle that states under our Constitution enjoy "equal sovereignty." The Court used the phrase repeatedly, including in the first paragraph of the opinion, and stressed that equal sovereignty was a "historic tradition" and "essential to the scheme upon which the Republic was organized." The takeaway from the case is that differential treatment of the states by the federal government, at least with respect to matters relating to its ability to pursue its legislative objectives, will be subject to heightened judicial scrutiny--burdens will have to be justified by a substantial federal interest and there must be a substantial link between the states singled out for less favorable treatment and the problem addressed. If, for example, the Congress were to use its Commerce Clause power to require 15 states to have their laws imposing taxes on Internet sales to residents be precleared by the Commerce Department, but left the other 35 free to enact such legislation without federal approval, such a law would almost certainly be struck down under Shelby's "equal sovereignty principle." The Tenth Amendment was included in the Bill of Rights to further define the balance of power between the federal government and the states. The amendment says that the federal government has only those powers specifically granted by the Constitution. These powers include the power to declare war, to collect taxes, to regulate interstate business activities and others that are listed in the articles.
Any power not listed, says the Tenth Amendment, is left to the states or the people. Although the Tenth Amendment does not specify what these “powers” may be, the U.S. Supreme Court has ruled that laws affecting family relations (such as marriage, divorce, and adoption), commerce that occurs within a state’s own borders, and local law enforcement activities, are among those specifically reserved to the states or the people.
