Although the Thirteenth Amendment abolished slavery, it did not resolve the legal status of former slaves under federal and state law. After the Civil War, many southern states passed “Black Codes” designed to severely restrict the lives of newly freed slaves and keep them in virtual slavery. Through the Fourteenth Amendment, former slaves were granted citizenship and promised “equal protection of the laws.” This protection from unreasonable discrimination eventually extended to other groups as well. The Fourteenth Amendment became the basis for claims of legal equality.

Because the Fourteenth Amendment specifically addressed the states, it drastically expanded the reach of the U.S. Constitution. The Supreme Court used the amendment to apply most provisions in the Bill of Rights to state governments. As a result, the Fourteenth Amendment is cited more often in modern litigation than any other. In fact, many constitutional scholars believe that, through its wide scope and promise of equality, the Fourteenth Amendment created a new Constitution.