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.

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.

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.

The opening sentence of Section One of the 14th Amendment defined U.S. citizenship: “All persons born or naturalized in the United States and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.”

This clearly repudiated the Supreme Court’s notorious 1857 Dred Scott decision, in which Chief Justice Roger Taney wrote that a Black man, even if born free, could not claim rights of citizenship under the federal constitution.

Section One's next clause was: “No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States.” This greatly expanded the civil and legal rights of all American citizens by protecting them from infringement by the states as well as by the federal government.

The third clause, “nor shall any State deprive any person of life, liberty or property, without due process of law,” expanded the due process clause of the Fifth Amendment to apply to the states as well as the federal government.

Over time, the Supreme Court has interpreted this clause to guarantee a wide array of rights against infringement by the states, including those enumerated in the Bill of Rights (freedom of speech, free exercise of religion, right to bear arms, etc.) as well as the right to privacy and other fundamental rights not mentioned elsewhere in the Constitution.

Finally, the “equal protection clause” (“nor deny to any person within its jurisdiction the equal protection of the laws”) was clearly intended to stop state governments from discriminating against Black Americans, and over the years would play a key role in many landmark civil rights cases.

Section Two of the 14th Amendment repealed the three-fifths clause (Article I, Section 2, Clause 3) of the original Constitution, which counted enslaved people as three-fifths of a person for the purpose of apportioning congressional representation. With slavery outlawed by the 13th Amendment, this clarified that all residents, regardless of race, should be counted as one whole person. This section also guaranteed that all male citizens over age 21, no matter their race, had a right to vote.

Southern states continued to deny Black men the right to vote using a collection of state and local statutes during the Jim Crow era. Subsequent amendments to the Constitution granted women the right to vote and lowered the legal voting age to 18.

Section Three of the amendment, gave Congress the authority to bar public officials, who took an oath of allegiance to the U.S. Constitution, from holding office if they "engaged in insurrection or rebellion" against the Constitution. The intent was to prevent the president from allowing former leaders of the Confederacy to regain power within the U.S. government after securing a presidential pardon. It states that a two-thirds majority vote in Congress is required to allow public officials who had engaged in rebellion to regain the rights of American citizenship and hold government or military office.

It states that: "No person shall be a Senator or Representative in Congress, or elector of President and Vice-President, or hold any office, civil or military, under the United States, or under any state, who, having previously taken an oath, as a member of Congress, or as an officer of the United States, or as a member of any State legislature, or as an executive or judicial officer of any State, to support the Constitution of the United States, shall have engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof."

Section Four of the 14th Amendment states that the "validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned." Historians believe the clause was intended to ensure the federal government would not repudiate its debts, as some former Confederate states had done.

It also prohibited payment of any debt owed to the defunct Confederate States of America and banned any payments to former enslavers as compensation for the loss of human "property" (enslaved people).

The fifth and final section of the 14th Amendment (“Congress shall have the power to enforce, by appropriate legislation, the provisions of this article”) echoed a similar enforcement clause in the 13th Amendment.

In giving Congress power to pass laws to safeguard the sweeping provisions of Section One, in particular, the 14th Amendment effectively altered the balance of power between the federal and state governments in the United States.

Nearly a century later, Congress used this authority to pass landmark civil rights legislation, including the Civil Rights Act of 1964 and the Voting Rights Act of 1965.

In its early decisions involving the 14th Amendment, the Supreme Court often limited the application of its protections on a state and local level.

In Plessy v. Ferguson (1896), the Court ruled that racially segregated public facilities did not violate the equal protection clause of the 14th Amendment, a decision that would help establish infamous Jim Crow laws throughout the South for decades to come.

But beginning in the 1920s, the Supreme Court increasingly applied the protections of the 14th Amendment on the state and local level. Ruling on appeal in the 1925 case Gitlow v. New York, the Court stated that the due process clause of the 14th Amendment protected the First Amendment rights of freedom of speech from infringement by the state as well as the federal government.

And in its famous 1954 ruling in Brown v. Board of Education, the Supreme Court overturned the “separate but equal” doctrine established in Plessy v. Ferguson, ruling that segregated public schools did in fact violate the equal protection clause of the 14th Amendment.

In other landmark rulings, the Supreme Court has cited the 14th Amendment in cases involving the use of contraception (1965’s Griswold v. Connecticut), interracial marriage (1967’s Loving v. Virginia), abortion (1973’s Roe v. Wade), a highly contested presidential election (2000’s Bush v. Gore), gun rights (2010’s McDonald v. Chicago) and same-sex marriage (2015’s Obergefell v. Hodges).

Amendment XIV, Constitution Center.
Akhil Reed Amar, America’s Constitution: A Biography (New York: Random House, 2005).
Fourteenth Amendment, HarpWeek.
10 Huge Supreme Court Cases About the 14th Amendment, Constitution Center.