The Reconstruction Amendments transformed American constitutional law in the wake of the Civil War. The Thirteenth Amendment (1865) abolished slavery and involuntary servitude in the United States, except as punishment for a crime, marking the formal end of the institution of slavery and empowering Congress to enforce abolition through appropriate legislation. The Fourteenth Amendment (1868) granted citizenship to all persons born or naturalized in the United States and guaranteed equal protection of the laws and due process to every person within a state's jurisdiction. The Fifteenth Amendment (1870) prohibited the federal and state governments from denying the right to vote on the basis of race, color, or previous condition of servitude. Together, these amendments dramatically expanded the scope of federal protection for individual rights and laid the constitutional foundation for the modern civil rights era.
The Fourteenth Amendment's Equal Protection Clause has become the most important provision for challenging discriminatory laws. It requires states to provide equal protection of the laws to all persons within their jurisdiction. When evaluating claims under this clause, courts apply different levels of judicial scrutiny depending on the classification at issue. Strict scrutiny, the highest standard, applies to laws involving suspect classifications such as race, national origin, or religion, or to those burdening fundamental rights; the government must show the law is narrowly tailored to serve a compelling government interest. Intermediate scrutiny applies primarily to gender-based classifications, requiring the law to be substantially related to an important government interest. Rational basis review, the most deferential standard, applies to most other laws and requires only that the law be rationally related to a legitimate government interest. These tiers of scrutiny shape the outcome of equal protection cases and define the limits of governmental power to treat people differently.
The Supreme Court's interpretation of the Equal Protection Clause has evolved dramatically. In Dred Scott v. Sandford (1857), the Court infamously ruled that enslaved people were not citizens and had no standing to sue, intensifying national divisions over slavery. Plessy v. Ferguson (1896) then upheld racial segregation under the "separate but equal" doctrine, legitimizing Jim Crow laws for nearly six decades. That decision was finally overturned by Brown v. Board of Education (1954), which unanimously held that racial segregation in public schools is inherently unequal and violates the Fourteenth Amendment. The Court has since struck down bans on interracial marriage in Loving v. Virginia (1967), recognized the right of same-sex couples to marry in Obergefell v. Hodges (2015), and in Regents of the University of California v. Bakke (1978), banned rigid racial quotas in university admissions while permitting race to be considered as one factor among many.
The Fourteenth Amendment's Due Process Clause has also been a powerful source of constitutional protection. Substantive due process safeguards certain fundamental rights from government interference regardless of the procedures followed, while procedural due process requires the government to follow fair procedures before depriving a person of life, liberty, or property. The Court has used substantive due process to recognize unenumerated rights. In Griswold v. Connecticut (1965), the Court established a constitutional right to privacy in the "penumbras" of several Bill of Rights provisions, striking down a ban on contraceptives for married couples. Roe v. Wade (1973) extended this right to a woman's decision to have an abortion, though Dobbs v. Jackson Women's Health Organization (2022) overturned Roe, holding that the Constitution does not confer a right to abortion and returning regulatory authority to the states. The Fifteenth Amendment's prohibition on racial discrimination in voting was reinforced by the Nineteenth Amendment (1920), which guaranteed women's right to vote, the Twenty-Fourth Amendment (1964), which banned poll taxes in federal elections, and the Twenty-Sixth Amendment (1971), which lowered the voting age to eighteen. In Shelby County v. Holder (2013), the Court struck down key provisions of the Voting Rights Act of 1965, significantly altering federal enforcement of voting rights, while Heart of Atlanta Motel v. United States (1964) upheld the Civil Rights Act of 1964 as a valid exercise of Congress's commerce power.