Though equality under the law is an American legal tradition arguably dating to the Declaration of Independence, formal equality for many groups remained elusive. Before passage of the Reconstruction Amendments, which included the Equal Protection Clause, American law did not extend constitutional rights to black Americans. Black people were considered inferior to white Americans, and subject to chattel slavery in the slave states until the Emancipation Proclamation and the ratification of the Thirteenth Amendment.

Even black Americans that were not enslaved lacked many crucial legal protections. In the 1857 Dred Scott v. Sandford decision, the Supreme Court rejected abolitionism and determined black men, whether free or in bondage, had no legal rights under the U.S. Constitution at the time. Currently, a plurality of historians believe that this judicial decision set the United States on the path to the Civil War, which led to the ratifications of the Reconstruction Amendments.

Before and during the Civil War, the Southern states prohibited speech of pro-Union citizens, anti-slavery advocates, and northerners in general, since the Bill of Rights did not apply to the states during such times. During the Civil War, many of the Southern states stripped the state citizenship of many whites and banished them from their state, effectively seizing their property. Shortly after the Union victory in the American Civil War, the Thirteenth Amendment was proposed by Congress and ratified by the states in 1865, abolishing slavery. Subsequently, many ex-Confederate states then adopted Black Codes following the war, with these laws severely restricting the rights of blacks to hold property, including real property (such as real estate), and many forms of personal property, and to form legally enforceable contracts. Such codes also established harsher criminal consequences for blacks than for whites.

Because of the inequality imposed by Black Codes, a Republican-controlled Congress enacted the Civil Rights Act of 1866. The Act provided that all persons born in the United States were citizens (contrary to the Supreme Court's 1857 decision in Dred Scott v. Sandford), and required that "citizens of every race and color ... [have] full and equal benefit of all laws and proceedings for the security of person and property, as is enjoyed by white citizens."

President Andrew Johnson vetoed the Civil Rights Act of 1866 amid concerns (among other things) that Congress did not have the constitutional authority to enact such a bill. Such doubts were one factor that led Congress to begin to draft and debate what would become the Equal Protection Clause of the Fourteenth Amendment. Additionally, Congress wanted to pr…

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With the return to originalist interpretations of the Constitution, many wonder what was intended by the framers of the reconstruction amendments at the time of their ratification. The Thirteenth Amendment abolished slavery but to what extent it protected other rights was unclear. After the Thirteenth Amendment the South began to institute Black Codes which were restrictive laws seeking to keep black Americans in a position of inferiority. The Fourteenth amendment was ratified by nervous Republicans in response to the rise of Black Codes. This ratification was irregular in many ways. First, there were multiple states that rejected the Fourteenth Amendment, but when their new governments were created due to reconstruction, these new governments accepted the amendment. There were also two states, Ohio and New Jersey, that accepted the amendment and then later passed resolutions rescinding that acceptance. The nullification of the two states' acceptance was considered illegitimate and both Ohio and New Jersey were included in those counted as ratifying the amendment.

Many historians have argued that Fourteenth Amendment was not originally intended to grant sweeping political and social rights to the citizens but instead to solidify the constitutionality of the 1866 Civil rights Act. While it is widely agreed that this was a key reason for the ratification of the Fourteenth Amendment, many historians adopt a much wider view. It is a popular interpretation that the Fourteenth Amendment was always meant to ensure equal rights for all those in the United States. This argument was used by Charles Sumner when he used the Fourteenth Amendment as the basis for his arguments to expand the protections afforded to black Americans.

Although the equal protection clause is one of the most cited ideas in legal theory, it received little attention during the ratification of the Fourteenth Amendment. Instead the key tenet of the Fourteenth Amendment at the time of its ratification was the Privileges or Immunities Clause. This clause sought to protect the privileges and immunities of all citizens which now included black men. The scope of this clause was substantially narrowed following the Slaughterhouse Cases in which it was determined that a citizen's privileges and immunities were only ensured at the Federal level and that it was government overreach to impose this standard on the states. Even in this halting decision the Court still acknowledged the context in which the Amendment was passed, stating that knowing the evils and injustice the Fourteenth Amendment was meant to combat is key in our legal understanding of its implications and purpose. With the abridgment of the Privileges or Immunities clause, legal arguments aimed at protecting black American's rights became more complex and that is when the equal protection clause started to gain attention for the arguments it could enhance.

During the debate in Congress, more than one version of the clause was considered. Here is the first version: "The Congress shall have power to make all laws which shall be necessary and proper to secure ... to all persons in the several states equal protection in the rights of life, liberty, and property." Bingham said about this version: "It confers upon Congress power to see to it that the protection given by the laws of the States shall be equal in respect to life and liberty and property to all persons." The main opponent of the first ver…

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Bingham said in a speech on March 31, 1871 that the clause meant no State could deny anyone "the equal protection of the Constitution of the United States ... [or] any of the rights which it guarantees to all men", nor deny to anyone "any right secured to him either by the laws and treaties of the United States or of such State." At that time, the meaning of equality varied from one state to another.

Four of the original thirteen states never passed any laws barring interracial marriage, and the other states were divided on the issue in the Reconstruction era. In 1872, the Alabama Supreme Court ruled that the state's ban on mixed-race marriage violated the "cardinal principle" of the 1866 Civil Rights Act and of the Equal Protection Clause. Almost a hundred years would pass before the U.S. Supreme Court followed that Alabama case (Burns v. State) in the case of Loving v. Virginia. In Burns, the Alabama Supreme Court said:

Marriage is a civil contract, and in that character alone is dealt with by the municipal law. The same right to make a contract as is enjoyed by white citizens, means the right to make any contract which a white citizen may make. The law intended to destroy the distinctions of race and color in respect to the rights secured by it.

As for public schooling, no states during this era of Reconstruction actually required separate schools for blacks. However, some states (e.g. New York) gave local districts discretion to set up schools that were deemed separate but equal. In contrast, Iowa and Massachusetts flatly prohibited segregated schools ever since the 1850s.

Likewise, some states were more favorable to women's legal status than others; New York, for example, had been giving women full property, parental, and widow's rights since 1860, but not the right to vote. No state or territory allowed women's suffrage when the Equal Protection Clause took effect in 1868. In contrast, at that time African American men had full voting rights in five states.