The following landmark court decisions changed the interpretation of existing law in the United States. Such a decision may settle the law in more than one way:
establishing a new legal principle or concept; overturning precedent based on its harmful effects or flaws in its reasoning; distinguishing a new principle that refines an existing principle, thus departing from prior practice without violating the rule of stare decisis; establishing a test or a measurable standard that can be applied by courts in future decisions.
In the United States, landmark court decisions come most frequently from the Supreme Court. United States courts of appeals may also make such decisions, particularly if the Supreme Court chooses not to review the case. Although many cases from state supreme courts are significant in developing the law of that state, only a few are so revolutionary that they announce standards that many other state courts then choose to follow.
Individual rights Discrimination based on race and ethnicity Dred Scott v. Sandford, People of African descent that are slaves or were slaves and subsequently freed, along with their descendants, cannot be United States citizens. Consequently, they cannot sue in federal court. Slavery in the United States cannot be prohibited in U.S. territories before they are admitted to the Union as doing so would violate the Due Process Clause of the Fifth Amendment. After the Civil War, this decision was voided by the Thirteenth and Fourteenth Amendments to the Constitution. Strauder v. West Virginia, The exclusion of individuals from juries solely because of their race is a violation of the Equal Protection Clause. This was the first time that the Supreme Court reversed a state criminal conviction due to a violation of a constitutional provision concerning criminal procedure. Yick Wo v. Hopkins, Racially discriminatory application of a racially neutral statute violates the Equal Protection Clause of the Fourteenth Amendment. Plessy v. Ferguson, Segregated facilities for blacks and whites are constitutional under the doctrine of separate but equal. As long as the separate facilities are equal in quality, then such separation is not unconstitutional. (De facto overruled by Brown v. Board of Education (1954)) Missouri ex rel. Gaines v. Canada, States with racially segregated educational systems cannot satisfy the "separate but equal" provision of Plessy merely by offering to pay for black students to be educated at an out-of-state institution; they must offer those opportunities in-state. Smith v. Allwright, Primary elections must be open to voters of all races, holding unconstitutional the white primary. Steele v. Louisville & Nashville Railway Co., Imposed duty of fair representation on labor unions, requiring that they represent all members of their bargaining unit equally, without regard to race or union membership (later understood to include other protected categories, and eventually all misfeasance or malfeasance in the act of representing a member). Korematsu v. United States, President Franklin D. Roosevelt's Executive Order 9066 is constitutional; therefore, American citizens of Japanese descent can be interned and deprived of their basic constitutional rights. This case featured the first application of strict scrutiny to racial discrimination by the government. (Overruled by Trump v. Hawaii (2018)) Morgan v. Virginia, A Virginia law that enforces segregation on interstate buses is unconstitutional. Shelley v. Kraemer, Courts may not enforce racial covenants on real estate. Sweatt v. Painter, and McLaurin v. Oklahoma State Regents, Segregation in higher education, in law schools and graduate programs respectively, violates the Equal Protection Clause. Laid the groundwork for the desegregation of all schools in Brown v. Board of Education, four years later. Henderson v. United States, The Interstate Commerce Act of 1887 makes it unlawful for a railroad that engages in interstate commerce to subject any particular person to any undue or unreasonable prejudice or disadvantage in any respect whatsoever. Hernandez v. Texas, The equal protection of the laws guaranteed by the Fourteenth Amendment covers any racial, national, and ethnic groups of the United States against whom discrimination can be proved. Brown v. Board of Education, Segregated schools in the states are unconstitutional because they violate the Equal Protection Clause of the Fourteenth Amendment. The Court found that the separate but equal doctrine adopted in Plessy "has no place in the field of public education". Bolling v. Sharpe, Segregated schools in the District of Columbia violate the Equal Protection Clause as incorporated against the federal government by the Due Process Clause of the Fifth Amendment. Sarah Keys v. Carolina Coach Company, 64 MCC 769 (1955) According to the Interstate Commerce Commission, the non-discrimination language of the Interstate Commerce Act of 1887 bans racial segregation on buses traveling across state lines. The Supreme Court later adopted and expanded this decision in Boynton v. Virginia (1960). Browder v. Gayle, 142 F.Supp. 707 (M.D. Ala. 1956) Bus segregation is unconstitutional under the Equal Protection Clause. Gomillion v. Lightfoot, Electoral district boundaries drawn only to disenfranchise blacks violate the Fifteenth Amendment. Boynton v. Virginia, Racial segregation in all forms of public transportation is illegal under the Interstate Commerce Act of 1887. Garner v. Louisiana, Peaceful sit-in demonstrators protesting segregationist policies cannot be arrested under a state's "disturbing the peace" laws. Heart of Atlanta Motel, Inc. v. United States, The Commerce Clause gives Congress power to force private businesses to abide by Title II of the Civil Rights Act of 1964, which prohibits discrimination in public accommodations. Loving v. Virginia, Laws that prohibit interracial marriage (anti-miscegenation laws) are unconstitutional. Swann v. Charlotte-Mecklenburg Board of Education, The busing of students to promote racial integration in public schools is constitutional. Griggs v. Duke Power Co., Interpreted the federal statute prohibiting employment discrimination to also prohibit "disparate impact," meaning employer policies that generate unequal employment outcomes regardless of whether the employer provably intended for them to do so, if those policies are not necessary for the employer's business purposes. Lau v. Nichols, The lack of supplemental language instruction in public school for students with limited English proficiency violates Title VI of the Civil Rights Act of 1964. Gates v. Collier, 501 F.2d 1291 (5th Cir. 1974) This decision brought an end to the trusty system and flagrant inmate abuse at the Mississippi State Penitentiary in Parchman, Mississippi. It was the first body of law developed in the Fifth Circuit that abolished racial segregation in prisons and held that a variety of forms of corporal punishment against prisoners is considered cruel and unusual punishment in violation of the Eighth Amendment. Runyon v. McCrary, Private schools that discriminate on the basis of race or establish racial segregation are in violation of federal law. Regents of the University of California v. Bakke, Racial quotas in educational institutions violate the Equal Protection Clause, but a more narrowly tailored use of race in admission decisions may be permissible. (Partially overruled by Students for Fair Admissions v. Harvard (2023)) Batson v. Kentucky, Prosecutors may not use peremptory challenges to dismiss jurors based on their race. Adarand Constructors, Inc. v. Peña, Race-based discrimination, including discrimination in favor of minorities (affirmative action), must pass strict scrutiny. Gratz v. Bollinger, The University of Michigan's “points system” of undergraduate affirmative action violated the Equal Protection Clause. Decided alongside Grutter v. Bollinger, which held constitutional the University of Michigan Law School's affirmative action program. Grutter v. Bollinger, A narrowly tailored use of race in student admission decisions may be permissible under the Equal Protection Clause because a diverse student body is beneficial to all students. This was hinted at in Regents v. Bakke (1978). (Overruled by Students for Fair Admissions v. Harvard (2023)) Schuette v. Coalition to Defend Affirmative Action, A Michigan state constitutional amendment that bans affirmative action does not violate the Equal Protection Clause. Students for Fair Admissions v. Harvard, Race-based affirmative action programs in civilian college admissions processes at colleges and universities receiving federal funds violate the Equal Protection Clause.
Discrimination based on sex Muller v. Oregon, Oregon's restrictions on the working hours of women are constitutional under the Fourteenth Amendment because they are justified by the strong state interest in protecting women's health. Glasser v. United States, The exclusion of women from the jury pool, other than members of the League of Women Voters who have attended a jury training class, violates the fair cross-section requirement of the Impartial Jury Clause of the Sixth Amendment. Noteworthy for being the first majority opinion of the Court to use the phrase "cross-section of the community" and the first jury discrimination case to invoke the Sixth Amendment rather than Equal Protection Clause of the Fourteenth Amendment. Phillips v. Martin Marietta Corp., An employer may not, in the absence of business necessity, refuse to hire women with preschool-age children while hiring men with such children. Reed v. Reed, Administrators of estates cannot be named in a way that discriminates on the basis of sex; the first time the Equal Protection Clause had been read by the Supreme Court as applying to sex. Stanley v. Illinois, Laws that automatically make the children of unmarried fathers wards of the state after their mother dies, but not the other way around, are unconstitutional. The first case in which the Supreme Court found men faced sex discrimination. Frontiero v. Richardson, Sex-based discriminations are inherently suspect. A statute that automatically extends military benefits to the spouses of male members of the uniformed services, but requires the spouses of female members to prove they are dependent on the servicemember's income, is unconstitutional. Taylor v. Louisiana, Systematic exclusion of women from jury service on the basis of having to register for jury duty violates a criminal defendant's Sixth and Fourteenth Amendment rights. Craig v. Boren, Setting different minimum ages for females (18) and males (21) to be allowed to buy beer is unconstitutional sex-based discrimination contrary to the Equal Protection Clause of the Fourteenth Amendment. Mississippi University for Women v. Hogan, The single-sex admissions policy of the Mississippi University for Women's School of Nursing violated the Equal Protection Clause of the Fourteenth Amendment. Price Waterhouse v. Hopkins, Discrimination against an employee on the basis of sex stereotyping—that is, a person's nonconformity to social or other expectations of that person's gender—constitutes impermissible sex discrimination, in violation of Title VII of the Civil Rights Act of 1964. The employer bears the burden of proving that the adverse employment action would have been the same if sex discrimination had not occurred. J.E.B. v. Alabama ex rel. T.B., Prosecutors may not use peremptory challenges to dismiss jurors based on their sex. United States v. Virginia, Sex-based "separate but equal" military training facilities violate the Equal Protection Clause. Oncale v. Sundowner Offshore Services, The protection of Title VII of the Civil Rights Act of 1964 against workplace discrimination "because of... sex" applied to harassment in the workplace between members of the same sex.