Answer:
The 14th Amendment to the U.S. Constitution, ratified in 1868, granted citizenship to all persons born or naturalized in the United States—including former enslaved people—and guaranteed all citizens “equal protection of the laws.” One of three amendments passed during the Reconstruction era to abolish slavery and establish civil and legal rights for Black Americans, it would become the basis for many landmark Supreme Court decisions over the years.
In its later sections, the 14th Amendment authorized the federal government to punish states that violated or abridged their citizens’ right to vote by proportionally reducing the states’ representation in Congress, and mandated that anyone who “engaged in insurrection” against the United States could not hold civil, military or elected office (without the approval of two-thirds of the House and Senate).
It also upheld the national debt, but exempted federal and state governments from paying any debts incurred by the former Confederate states.
Reconstruction
Abraham Lincoln’s assassination in April 1865 left his successor, President Andrew Johnson, to preside over the complex process of incorporating former Confederate states back into the Union after the Civil War and establishing former enslaved people as free and equal citizens.
Johnson, a Democrat (and former slaveholder) from Tennessee, supported emancipation, but he differed greatly from the Republican-controlled Congress in his view of how Reconstruction should proceed. Johnson showed relative leniency toward the former Confederate states as they were reintroduced into the Union.
But many northerners were outraged when the newly elected southern state legislatures—largely dominated by former Confederate leaders—enacted black codes, which were repressive laws that strictly regulated the behavior of Black citizens and effectively kept them dependent on white planters.
READ MORE: How the Black Codes Limited African American Progress After the Civil War
Civil Rights Act of 1866
In creating the Civil Rights Act of 1866, Congress was using the authority given it to enforce the newly ratified 13th Amendment, which abolished slavery, and protect the rights of Black Americans.
Johnson vetoed the bill, and though Congress successfully overrode his veto and made it into law in April 1866—the first time in history that Congress overrode a presidential veto of a major bill—even some Republicans thought another amendment was necessary to provide firm constitutional grounds for the new legislation.
Thaddeus Stevens
In late April, Representative Thaddeus Stevens introduced a plan that combined several different legislative proposals (civil rights for Black people, how to apportion representatives in Congress, punitive measures against the former Confederate States of America and repudiation of Confederate war debt), into a single constitutional amendment. After the House and Senate both voted on the amendment by June 1866, it was submitted to the states for ratification.
President Johnson made clear his opposition to the 14th Amendment as it made its way through the ratification process, but Congressional elections in late 1866 gave Republicans veto-proof majorities in both the House and Senate.
Southern states also resisted, but Congress required them to ratify the 13th and 14th Amendments as a condition of regaining representation in Congress, and the ongoing presence of the Union Army in the former Confederate states ensured their compliance.
On July 9, 1868, Louisiana and South Carolina voted to ratify the 14th Amendment, making up the necessary three-fourths majority.