The most important Supreme Court cases, grouped by topic, cluster into about nine areas of constitutional law: federal power and the separation of powers, civil rights and equal protection, voting, criminal procedure, free speech, privacy, LGBTQ+ rights, the Second Amendment, and religion. Each ruling below created binding precedent that lower courts still follow, and together they trace how the Constitution has been read and re-read across more than two centuries. Use the sections as a map: find the subject you care about, then the cases that defined it.
Federal Power and the Separation of Powers
Marbury v. Madison (1803) is the structural case that makes everything else possible. The Court held that it has the power to strike down acts of Congress that conflict with the Constitution, establishing the doctrine of judicial review.1Justia. Marbury v. Madison, 5 U.S. 137 (1803) Every constitutional challenge since has rested on the authority Marbury created.
McCulloch v. Maryland (1819) drew the line between federal and state power. The Court ruled that Congress has implied powers beyond those explicitly listed in the Constitution, upholding the creation of a national bank, and declared that states cannot tax or otherwise obstruct federal operations because the power to tax is the power to destroy.2Justia. McCulloch v. Maryland, 17 U.S. 316 (1819)
United States v. Nixon (1974) tested executive privilege. The Court acknowledged that a president needs some confidential space to carry out the duties of office but held that the privilege is not absolute; when a criminal investigation requires specific evidence, that need outweighs the president’s general interest in secrecy.3Justia. United States v. Nixon, 418 U.S. 683 (1974)
Loper Bright Enterprises v. Raimondo (2024) overturned a forty-year framework governing federal agencies. Under the prior rule from Chevron v. Natural Resources Defense Council (1984), courts deferred to an agency’s reasonable interpretation of an ambiguous statute. The Court rejected that approach, holding that the Administrative Procedure Act requires courts to use their own independent judgment when deciding whether an agency acted within its legal authority.4Justia. Loper Bright Enterprises v. Raimondo, 603 U.S. ___ (2024) Federal regulations are now easier to challenge in court.
Civil Rights and Equal Protection
The Fourteenth Amendment prohibits states from denying any person equal protection under the law,5Constitution Annotated. Fourteenth Amendment – Equal Protection and Other Rights and how the Court has read that clause shifted dramatically over the twentieth century.
Plessy v. Ferguson (1896) upheld a Louisiana law requiring separate railway cars for white and Black passengers, creating the “separate but equal” doctrine that gave constitutional cover to segregation for nearly sixty years.6Justia. Plessy v. Ferguson, 163 U.S. 537 (1896)
Brown v. Board of Education (1954) dismantled it. In a unanimous decision, the Court declared that racially segregated public schools are inherently unequal.7Justia. Brown v. Board of Education of Topeka, 347 U.S. 483 (1954) A follow-up decision the next year ordered school districts to desegregate “with all deliberate speed.”8National Archives. Brown v. Board of Education (1954)
Loving v. Virginia (1967) struck down state laws banning interracial marriage, holding that these prohibitions violated both the Equal Protection and Due Process Clauses.9Justia. Loving v. Virginia, 388 U.S. 1 (1967)
Students for Fair Admissions v. Harvard (2023) held that race-conscious admissions programs at Harvard and the University of North Carolina violated the Equal Protection Clause. The Court found that both programs used race in ways that lacked measurable objectives, relied on racial stereotyping, and had no meaningful end point.10Justia. Students for Fair Admissions, Inc. v. President and Fellows of Harvard College, 600 U.S. 181 (2023) The decision effectively ended affirmative action in college admissions.
Voting Rights and Elections
Baker v. Carr (1962) opened federal courts to challenges over how states draw legislative districts. Before Baker, courts treated redistricting as a political question they had no power to resolve; the Court held that voters alleging unequal representation under the Fourteenth Amendment could bring their claims to federal court.11Justia. Baker v. Carr, 369 U.S. 186 (1962) That opened the path to the “one person, one vote” principle.
Shelby County v. Holder (2013) struck down the formula that determined which states and counties with histories of racial discrimination had to get federal approval before changing their voting laws under the Voting Rights Act of 1965. The Court ruled the formula unconstitutional because it relied on decades-old data.12Justia. Shelby County v. Holder, 570 U.S. 529 (2013) The approval requirement itself survived but is inoperable without a formula, and Congress has not passed a replacement.
Rucho v. Common Cause (2019) drew the line at partisan gerrymandering. The Court held that claims about partisan line-drawing are political questions federal courts cannot resolve, because no manageable judicial standards exist for deciding when such line-drawing goes too far.13Justia. Rucho v. Common Cause, 588 U.S. ___ (2019) Challenges to partisan maps must now proceed through state courts or the political process.
Criminal Procedure and the Rights of the Accused
The Bill of Rights protects people accused of crimes, and the Fourteenth Amendment extends most of those protections against state governments.14Constitution Annotated. Amdt14.S1.5.5.1 Overview of Procedural Due Process in Criminal Cases Four cases shape what that means in practice.
Gideon v. Wainwright (1963) held that states must provide a lawyer to defendants who cannot afford one, because the right to counsel is fundamental to a fair trial.15Justia. Gideon v. Wainwright, 372 U.S. 335 (1963) Public defender offices expanded across the country to meet the obligation.
Miranda v. Arizona (1966) required law enforcement to warn suspects in custody of their rights before questioning: the right to remain silent, notice that anything they say can be used against them, the right to an attorney, and the right to appointed counsel if they cannot afford one. Statements obtained without these warnings are generally inadmissible at trial.16Justia. Miranda v. Arizona, 384 U.S. 436 (1966)
Mapp v. Ohio (1961) applied the exclusionary rule to state courts, holding that evidence obtained through searches or seizures that violate the Fourth Amendment cannot be used in state criminal prosecutions.17Justia. Mapp v. Ohio, 367 U.S. 643 (1961) Police generally must obtain a warrant based on probable cause before searching someone’s property.
Riley v. California (2014) extended Fourth Amendment protections into the digital age. The Court unanimously held that police cannot search the digital contents of a cell phone seized during an arrest without first obtaining a warrant, recognizing that modern phones contain far more private information than anything a person might carry in a wallet.18Justia. Riley v. California, 573 U.S. 373 (2014)
Freedom of Speech and Expression
Schenck v. United States (1919) produced the “clear and present danger” test, holding that speech creating a clear and immediate risk of a serious harm Congress can prevent falls outside First Amendment protection.19Justia. Schenck v. United States, 249 U.S. 47 (1919) Fifty years later, Brandenburg v. Ohio (1969) replaced that standard with a more protective one: the government can only punish advocacy of illegal action when the speech is both intended to produce imminent lawless action and likely to do so.20Justia. Brandenburg v. Ohio, 395 U.S. 444 (1969) That shift made it far harder for the government to criminalize unpopular political speech.
Tinker v. Des Moines (1969) established that students do not “shed their constitutional rights to freedom of speech or expression at the schoolhouse gate.” Students who wore black armbands to protest the Vietnam War were protected because their quiet expression did not disrupt the school.21Justia. Tinker v. Des Moines Independent Community School District, 393 U.S. 503 (1969)
Texas v. Johnson (1989) held that burning the American flag is protected expressive conduct under the First Amendment. The Court found the act was political in nature and that the government’s interest in preserving the flag as a symbol did not justify punishing the expression.22Justia. Texas v. Johnson, 491 U.S. 397 (1989) Laws targeting the content of speech face the highest level of judicial scrutiny, while reasonable restrictions on when, where, and how people express themselves are allowed if neutral toward the message.23Constitution Annotated. Amdt1.7.3.1 Overview of Content-Based and Content-Neutral Regulation of Speech
Citizens United v. FEC (2010) extended First Amendment protection to corporate and union spending on independent political communications. The Court struck down provisions of the Bipartisan Campaign Reform Act that had prohibited corporations and unions from using general treasury funds for election-related broadcasts before elections.24Justia. Citizens United v. FEC, 558 U.S. 310 (2010) The decision opened the door to greatly increased spending in elections.
Privacy and Substantive Due Process
The Constitution never uses the word “privacy,” but the Court has recognized that certain personal decisions are protected from government interference.
Griswold v. Connecticut (1965) struck down a state law prohibiting the use of contraceptives by married couples, reasoning that a right to privacy exists in the “penumbras” of several amendments in the Bill of Rights.25Justia. Griswold v. Connecticut, 381 U.S. 479 (1965) Griswold became the foundation for later cases on personal autonomy and bodily integrity.
Roe v. Wade (1973) built on that foundation, holding that the Due Process Clause of the Fourteenth Amendment protected a woman’s right to choose to have an abortion. The Court created a trimester framework that balanced the woman’s rights against the government’s growing interest in protecting potential life.26Justia. Roe v. Wade, 410 U.S. 113 (1973)
Dobbs v. Jackson Women’s Health Organization (2022) overruled Roe entirely. The Court held that the Constitution does not confer a right to abortion and returned authority to regulate the procedure to state legislatures.27Justia. Dobbs v. Jackson Women’s Health Organization, 597 U.S. ___ (2022) The majority applied a standard requiring that any right protected under substantive due process must be deeply rooted in the nation’s history and tradition.28Constitution Annotated. Amdt14.S1.6.3.1 Overview of Noneconomic Substantive Due Process That historical test now governs which unenumerated rights receive constitutional protection.
LGBTQ+ Rights
Obergefell v. Hodges (2015) held that the Fourteenth Amendment guarantees same-sex couples the right to marry. The Court found that marriage is a fundamental liberty rooted in personal autonomy, intimate association, and the protection of families, and that both the Due Process and Equal Protection Clauses required states to license and recognize same-sex marriages.29Justia. Obergefell v. Hodges, 576 U.S. 644 (2015)
Bostock v. Clayton County (2020) held that firing someone for being gay or transgender constitutes sex discrimination under Title VII of the Civil Rights Act of 1964. The majority’s reasoning was simple: if an employer would not have fired a person but for their sex, then sex played a role in the decision, which is exactly what the statute forbids.30Justia. Bostock v. Clayton County, 590 U.S. ___ (2020) The ruling applied to every employer covered by Title VII.
Second Amendment and Firearms
District of Columbia v. Heller (2008) established that the Second Amendment protects an individual’s right to possess firearms for traditionally lawful purposes, including self-defense in the home, regardless of militia membership. The Court struck down a Washington, D.C., handgun ban but emphasized that the right is not unlimited; the government may still prohibit possession by felons, restrict firearms near schools and government buildings, and regulate commercial sales.31Justia. District of Columbia v. Heller, 554 U.S. 570 (2008)
New York State Rifle & Pistol Association v. Bruen (2022) set the standard for evaluating gun regulations. When the Second Amendment’s text covers a person’s conduct, the Constitution presumptively protects it, and the government can only justify a restriction by showing it is consistent with the nation’s historical tradition of firearms regulation.32Justia. New York State Rifle and Pistol Association, Inc. v. Bruen, 597 U.S. ___ (2022) This historical-tradition test replaced the means-end scrutiny lower courts had applied since Heller, and it has generated extensive litigation.
Religion and the Establishment Clause
Kennedy v. Bremerton School District (2022) reshaped how courts analyze claims that the government is improperly promoting religion. A public school football coach had been disciplined for praying on the field after games. The Court sided with the coach and formally abandoned the Lemon test, a three-part framework from 1971 that had asked whether government actions had a secular purpose, whether they advanced or inhibited religion, and whether they created excessive entanglement with religion. In its place, the Court directed that Establishment Clause questions should be resolved by reference to historical practices and the original understanding of the First Amendment.33Justia. Kennedy v. Bremerton School District, 597 U.S. ___ (2022) Because the coach’s private prayer did not coerce students, the Court found no constitutional violation. Lower courts are still working out what the shift from a structured test to a history-based inquiry will mean in practice.