Since its adoption, the Constitution not only has defined the authority of the federal government and states; it also has functioned to “secure the blessings of liberty” for “the people of the United States.” Its amendments have rendered the definition of the people more inclusive over time.

From its framing at the Constitutional Convention, delegates preserved slavery. Abolition had begun in the North, but the institution was robust in the South. James Madison of Virginia noted that “States were divided into different interests not by their difference of size, but ... principally from the effects of their having or not having slaves.” Compromises were hammered out to bridge that divide and assure ratification. Article I, Section 2 counted “three-fifths” of the enslaved with the free population in allocating Congressmen and direct taxes; Section 8 empowered Congress to “suppress insurrections”; and Section 9 forbad outlawing the slave trade before 1808. Article IV, Section 2 provided for the return of fugitive slaves.

Meantime, pressured by Anti-Federalist demands for individual liberties, Congress adopted the first ten amendments or “the Bill of Rights” (1791). The Amendment I prohibits establishment of religion or barring its free exercise; abridging freedom of speech, the press, assembly, and right to petition the government for redress. II authorizes a militia for securing the people's right to keep and bear arms. III bars the arbitrary quartering of troops. IV bars unreasonable search and seizure. Similarly, V ensures a person accused of a felony “due process of law,” including immunity from double jeopardy and self-incrimination. VI establishes the right to counsel for defense, to face accusing witnesses, to a public and timely jury trial. VII provides for a civil jury trial. VIII disallows excessive bail and cruel and unusual punishment. IX protects rights “retained by the people” with those enumerated in the Constitution. X reserves to the states powers not delegated to the United States.

Constitutional inclusion evolved after the Civil War. Amendment XIII (1865) abolished slavery. XIV (1868) made “all persons born or naturalized” in the United States citizens, entitling them to “due process of law” and “equal protection of the laws.” XV (1870) guaranteed citizens’ right to vote regardless of “race, color, or previous condition of servitude.” African Americans, among other groups formerly excluded, struggled for equal citizenship. Seeking “due process” and “equal protection,” they protested and sued against racial discrimination, segregation, and violence.