The most important landmark voting rights cases are the Supreme Court decisions that have defined who can vote, whose vote counts equally, and what rules a government can impose at the ballot box. The Constitution contains no affirmative right to vote. The 15th, 19th, 24th, and 26th Amendments instead bar the government from denying the vote on specific grounds, and the Court decides what those protections mean in practice.1National Archives. 15th Amendment to the U.S. Constitution: Voting Rights The rulings below trace that work from 1915 to 2024.
Dismantling Jim Crow-Era Barriers
After the Civil War, several states built race-neutral-sounding rules that locked Black citizens out of elections. The Court took them apart one at a time.
Guinn v. United States (1915)
Oklahoma required voters to pass a literacy test but exempted anyone whose ancestors could vote before 1866. Because Black Americans were enslaved before that date, the exemption ran almost entirely to white voters. In Guinn v. United States, the Court struck down the grandfather clause as a violation of the 15th Amendment.2Cornell Law Institute. FRANK GUINN and J. J. Beal v. UNITED STATES It was the first significant signal that courts would look past a rule’s surface to its real effect on minority voters.
Smith v. Allwright (1944)
Texas let the Democratic Party restrict its primaries to white voters, arguing that a political party was a private group beyond the reach of the 15th Amendment. The Court rejected that in Smith v. Allwright, holding that primaries are an integral part of the public election process and a party cannot use “private” status to exclude voters by race.3Justia U.S. Supreme Court Center. Smith v. Allwright, 321 U.S. 649 (1944) Across much of the one-party South, winning the Democratic primary meant winning the general election, so the white primary had been one of the era’s most effective disenfranchisement tools.
Harper v. Virginia Board of Elections (1966)
Several states charged a fee to vote. The amounts were small, but they fell hardest on poor Black citizens in the South. The 24th Amendment, ratified in 1964, banned poll taxes in federal elections.4National Archives. The Constitution: Amendments 11-27 Virginia still imposed a $1.50 poll tax in its own elections. In Harper v. Virginia Board of Elections, the Court held that conditioning the right to vote on any fee violates the 14th Amendment’s Equal Protection Clause, declaring that wealth is unrelated to a citizen’s ability to participate.5Justia U.S. Supreme Court Center. Harper v. Virginia Bd. of Elections, 383 U.S. 663 (1966) Together with the amendment, the decision eliminated the poll tax at every level.
One Person, One Vote
Once discriminatory prerequisites fell, unequal district populations became the next frontier. If one district held ten times as many people as another, residents of the larger district had one-tenth the influence per person.
Baker v. Carr (1962)
Tennessee had not redrawn its legislative districts since 1901 despite huge population shifts to cities. In Baker v. Carr, the Court held that federal courts have jurisdiction to hear challenges to legislative apportionment, rejecting the older view that districting was a political question the judiciary should avoid.6Justia U.S. Supreme Court Center. Baker v. Carr, 369 U.S. 186 (1962) The ruling didn’t say what equal representation required. It opened the courthouse door.
Reynolds v. Sims (1964)
Two years later, the Court walked through it. Reynolds v. Sims established the “one person, one vote” principle, holding that the Equal Protection Clause requires both chambers of a state legislature to be apportioned by population.7Justia. Reynolds v. Sims, 377 U.S. 533 (1964) Legislators represent people, Chief Justice Warren wrote, not trees or acres. The decision forced nearly every state to redraw its maps and shifted political power toward cities and suburbs.
A later companion, Evenwel v. Abbott (2016), upheld the use of total population rather than only eligible voters when equalizing districts, reasoning that representatives serve all residents.8Justia. Evenwel v. Abbott, 578 U.S. ___ (2016) A state legislative map presumptively complies if the maximum deviation between the largest and smallest district stays under 10%.
The Voting Rights Act in the Supreme Court
The Voting Rights Act of 1965 gave the federal government its most powerful tools. Section 5 required certain jurisdictions to get federal approval before changing election rules. Section 2 allowed lawsuits nationwide against any voting practice that resulted in racial discrimination. The Court’s treatment of both has swung from strong endorsement to significant narrowing.
South Carolina v. Katzenbach (1966)
South Carolina immediately challenged the Act as federal overreach. In South Carolina v. Katzenbach, the Court disagreed, holding that the 15th Amendment gives Congress broad power to combat racial discrimination in voting.9Justia. South Carolina v. Katzenbach, 383 U.S. 301 (1966) The decision upheld Section 5 preclearance and the Section 4(b) coverage formula that targeted jurisdictions with literacy tests and low registration or turnout in 1964. Case-by-case litigation, the Court recognized, was too slow to keep pace with the ways states invented new barriers.
Thornburg v. Gingles (1986)
Section 2 prohibits voting practices that result in unequal opportunity for minority voters. Thornburg v. Gingles laid out a three-part test for proving that an electoral structure dilutes minority voting power. A challenger must show that the minority group is large and geographically compact enough to form a majority in a single district, that the group is politically cohesive, and that white voters typically vote as a bloc to defeat the minority group’s preferred candidates.10Justia. Thornburg v. Gingles, 478 U.S. 30 (1986) That framework became the foundation for decades of redistricting litigation and the creation of majority-minority districts.
Shelby County v. Holder (2013)
Nearly fifty years after Katzenbach, the Court reversed course on federal oversight. A 5–4 majority in Shelby County v. Holder struck down the Section 4(b) coverage formula, finding it unconstitutional because it relied on data from the 1960s and 1970s.11Cornell Law Institute. SHELBY COUNTY v. HOLDER The Court invoked a “fundamental principle of equal sovereignty” among states, holding that Congress cannot subject some states to extraordinary federal oversight based on conditions that no longer exist. Section 5 remained on the books but became unenforceable with no valid formula to identify covered jurisdictions. Within hours of the decision, several states began enacting voting restrictions that would previously have needed federal approval.
Brnovich v. Democratic National Committee (2021)
With preclearance effectively dead, Section 2 became the main federal tool against discriminatory rules. The Court narrowed that tool too. Brnovich v. Democratic National Committee upheld two Arizona voting restrictions and set out five factors for courts to weigh in Section 2 challenges: the size of the burden, whether the practice departs from what was standard when Congress last amended Section 2 in 1982, the size of any racial disparity, the state’s full voting system rather than the challenged rule in isolation, and the strength of the state’s interests such as fraud prevention.12Justia. Brnovich v. Democratic National Committee, 594 U.S. ___ (2021) The practical effect made it harder to succeed under Section 2, because challengers now must show a substantial disparity across a state’s entire voting system rather than point to a single restrictive rule.
Voter ID
Photo identification became one of the most contested voting issues after Shelby County removed the preclearance backstop. The leading case remains Crawford v. Marion County Election Board (2008), which upheld Indiana’s law requiring government-issued photo ID to vote in person.13Justia. Crawford v. Marion County Election Bd., 553 U.S. 181 (2008) The plurality applied a balancing test, weighing the burden on voters against the state’s interests in deterring fraud, modernizing procedures, and maintaining public confidence. Indiana’s interests were sufficient to justify what the Court called a modest burden. The decision did not bless every voter ID law. A stricter one imposing a heavier burden could still fail the balance if the state’s justifications were weaker.
Gerrymandering
Redistricting litigation splits into two legally distinct problems: lines drawn to disadvantage racial minorities, and lines drawn to entrench a political party. The Court treats them very differently.
Rucho v. Common Cause (2019)
In Rucho v. Common Cause, a 5–4 majority held that partisan gerrymandering claims are political questions federal courts cannot decide.14Justia. Rucho v. Common Cause, 588 U.S. ___ (2019) The Court acknowledged that excessive partisan gerrymandering is “incompatible with democratic principles” but found no judicially manageable standard for how much partisanship is too much. Federal courthouses closed to those claims. State courts applying state constitutions remained open.
Alexander v. South Carolina NAACP (2024)
Racial gerrymandering is still justiciable, but proving it is difficult when race and party affiliation overlap. In Alexander v. South Carolina State Conference of the NAACP, the Court held that a plaintiff must show race was the “predominant factor” driving the legislature’s choices, overriding neutral criteria like compactness and contiguity.15Justia. Alexander v. South Carolina State Conference of the NAACP, 602 U.S. ___ (2024) Courts start with a presumption that the legislature acted in good faith. Where race and partisanship correlate closely, a challenger essentially needs to produce an alternative map showing the legislature could have hit its legitimate political goals while drawing more racially balanced districts. Without that alternative, the claim usually fails.
Moore v. Harper (2023)
Some legislators pushed the “independent state legislature theory,” arguing that because the Constitution’s Elections Clause vests power in state legislatures to regulate federal elections, state courts have no authority to review those rules. Moore v. Harper rejected that theory, holding that when state legislatures set rules for federal elections, they remain subject to ordinary review under their state constitutions.16Justia. Moore v. Harper, 600 U.S. ___ (2023) The ruling preserved state courts as a check on legislative power over elections. That matters especially after Rucho, because state courts are now the primary forum for partisan gerrymandering challenges.
Felon Disenfranchisement
Richardson v. Ramirez (1974) held that states may disenfranchise people convicted of felonies without violating the Equal Protection Clause.17Justia. Richardson v. Ramirez, 418 U.S. 24 (1974) The Court pointed to Section 2 of the 14th Amendment, which contemplates reducing a state’s congressional representation for denying the vote except when the denial is for “participation in rebellion, or other crime.” That language, the Court held, is a direct endorsement of felon disenfranchisement and places it outside the reach of equal protection challenges that had struck down poll taxes and similar barriers.
The practical result is that roughly 4.4 million Americans are currently barred from voting because of a felony conviction, though the rules vary enormously by state. Maine and Vermont never strip voting rights. About two dozen states restore them automatically at the end of a prison sentence. Others require completion of parole and probation, and some condition restoration on payment of outstanding fines and fees. Around ten states strip rights indefinitely for certain offenses and require a governor’s pardon or similar action. Because the Court treats this as a matter of state legislative discretion, whether a formerly incarcerated person can vote depends almost entirely on geography.
Youth Voting and the 26th Amendment
Oregon v. Mitchell (1970) issued a fractured ruling on the Voting Rights Act Amendments of 1970. The justices agreed Congress could set the voting age at 18 for federal elections but held it lacked the power to do so for state and local elections.18Justia. Oregon v. Mitchell, 400 U.S. 112 (1970) States would have needed to maintain two separate voter rolls. That impracticality drove the rapid ratification of the 26th Amendment in 1971, which lowered the voting age to 18 for every election.4National Archives. The Constitution: Amendments 11-27
Read together, these decisions show the Court moving in both directions over more than a century: expanding access when it struck down grandfather clauses, white primaries, poll taxes, and malapportioned districts, and contracting federal enforcement when it dismantled the preclearance formula, narrowed Section 2, and closed the federal courts to partisan gerrymandering claims. The rules governing an American vote today are the product of that back and forth.