The Equal Protection Clause, part of the Fourteenth Amendment to the United States Constitution, provides that "no state shall… deny to any person within its jurisdiction the equal protection of the laws." The Equal Protection Clause can be seen as an attempt to secure the promise of the United States' professed commitment to the proposition that "all men are created equal" by empowering the judiciary to enforce that principle against the states.
More concretely, the Equal Protection Clause, along with the rest of the Fourteenth Amendment, marked a great shift in American constitutionalism. Before the enactment of the Fourteenth Amendment, the Bill of Rights protected individual rights only from invasion by the federal government. After the Fourteenth Amendment was enacted, the Constitution also protected rights from abridgement by state governments, even including some rights that arguably were not protected from abridgement by the federal government. In the wake of the Fourteenth Amendment, the states could not, among other things, deprive people of the equal protection of the laws. What exactly such a requirement means, of course, has been the subject of great debate; and the story of the Equal Protection Clause is the gradual explication of its meaning.
One of the main limitations in the Equal Protection Clause is that it limits only the powers of government bodies, and not the private parties on whom it confers equal protection. This limitation has existed since 1883 and has not been overturned. However, since the 1960s, Congress has passed most civil rights legislation under its Commerce Clause power.