The Equal Protection Clause of the 14th Amendment bars any state from denying a person “the equal protection of the laws,” and the most important Supreme Court cases interpreting that clause built the framework courts still use to decide when the government can treat one group differently from another.1Congress.gov. Fourteenth Amendment The clause doesn’t demand identical treatment. It demands a good enough reason for every line the government draws, and the worse the history of discrimination against the group on the losing side of that line, the stronger the reason has to be.
The Three Tiers of Review
Almost every equal protection case turns on which standard a court applies. There are three.
Rational basis review is the default. The government only needs to show that a law is rationally connected to a legitimate purpose. Most economic regulations and classifications that don’t involve a historically disadvantaged group face this test, and most survive it.
Intermediate scrutiny applies to classifications based on sex. The government must show the law furthers an important objective and that the classification is substantially related to achieving it.
Strict scrutiny is the hardest standard. Courts apply it to classifications based on race, national origin, and alienage. The government must prove a compelling interest and show the law is narrowly tailored to that interest. Very few laws survive it.
The tiers aren’t fully rigid. In City of Cleburne v. Cleburne Living Center (1985), the Court refused to recognize intellectual disability as a suspect classification but still struck down a zoning ordinance that blocked a group home, finding the regulation rested on “irrational prejudice” rather than any legitimate concern.2Justia. City of Cleburne v. Cleburne Living Center, Inc., 473 U.S. 432 (1985) Rational basis with real teeth, in other words.
Race and the End of Separate but Equal
The Court’s first major reading of the clause tolerated racial segregation. In Plessy v. Ferguson (1896), the justices held that states could legally require separate accommodations for different races as long as the facilities were supposedly equal.3Justia. Plessy v. Ferguson, 163 U.S. 537 (1896) That “separate but equal” doctrine gave legal cover to decades of state-sponsored segregation in schools, transportation, restaurants, and nearly every public space in the South.
The doctrine collapsed in 1954. A unanimous Court in Brown v. Board of Education ruled that segregated public schools are inherently unequal, no matter how comparable the buildings or textbooks.4Justia. Brown v. Board of Education of Topeka, 347 U.S. 483 (1954) Chief Justice Warren wrote that separating children solely by race “generates a feeling of inferiority as to their status in the community that may affect their hearts and minds in a way unlikely ever to be undone.” Separation itself was the injury.
The same day, the Court decided Bolling v. Sharpe, which addressed segregated schools in Washington, D.C. Because the 14th Amendment applies only to states, the justices located an equal protection component inside the Fifth Amendment’s Due Process Clause, reasoning that “it would be unthinkable that the same Constitution would impose a lesser duty on the Federal Government” than on the states.5Justia. Bolling v. Sharpe, 347 U.S. 497 (1954) Bolling ensures equal protection principles reach the federal government too.
A year later, Brown II ordered desegregation “with all deliberate speed,” phrasing that many Southern states used to delay compliance.6National Archives. Brown v. Board of Education Courts spent the next two decades enforcing orders and striking down laws requiring racial separation in parks, courtrooms, and public housing. None of them survived strict scrutiny.
Sex Discrimination
Equal protection reached sex discrimination later than race. In Reed v. Reed (1971), the Court struck down an Idaho probate rule that automatically preferred men over women when both applied to administer a deceased person’s estate. It was the first time a sex-based law fell under the Equal Protection Clause.7Justia. Reed v. Reed, 404 U.S. 71 (1971)
Reed invalidated the law without formally adopting a heightened standard. That came in Craig v. Boren (1976), where the Court created intermediate scrutiny and applied it to an Oklahoma law setting different drinking ages for men and women.8Legal Information Institute. Craig v. Boren, 429 U.S. 190 (1976)
Two decades later, United States v. Virginia (1996) raised the bar further. Challenging the all-male admissions policy at the Virginia Military Institute, Justice Ginsburg wrote that any party defending gender-based government action must show an “exceedingly persuasive justification,” and cannot rely on generalizations about inherent differences between men and women.9Justia. United States v. Virginia, 518 U.S. 515 (1996) Whether that language created something stricter than classic intermediate scrutiny is still debated. The practical result was not: states can no longer lean on gender stereotypes to exclude women from public institutions.
Voting and Legislative Districting
Equal protection also governs the mechanics of elections. In Reynolds v. Sims (1964), the Court established the “one person, one vote” principle, holding that seats in both houses of a state legislature must be apportioned by population.10Justia. Reynolds v. Sims, 377 U.S. 533 (1964) Before Reynolds, rural districts routinely had far fewer residents than urban ones, giving rural voters outsized political weight. States had to redraw their maps so each citizen’s vote carried roughly equal weight.
Racial Gerrymandering
Drawing district lines to achieve racial goals raises its own equal protection problems. Shaw v. Reno (1993) held that a redistricting plan “so irrational on its face that it can be understood only as an effort to segregate voters into separate districts on the basis of race” states a valid equal protection claim.11Justia. Shaw v. Reno, 509 U.S. 630 (1993) The case involved a North Carolina congressional district so oddly shaped it stretched thin along an interstate highway for roughly 160 miles. When race is the predominant factor in drawing boundaries, strict scrutiny applies.
Uniform Election Standards
The clause took center stage in the 2000 presidential election. In Bush v. Gore, the Court found that Florida’s manual recount violated equal protection because the standards for counting ballots varied from county to county and even between teams within the same county.12Justia. Bush v. Gore, 531 U.S. 98 (2000) Seven justices agreed on the violation; five agreed on halting the recount. Once a state grants the right to vote, it cannot “by later arbitrary and disparate treatment, value one person’s vote over that of another.”
University Admissions
For nearly five decades the Court wrestled with whether public universities could consider an applicant’s race. The arc moved steadily from permitting race-conscious policies to prohibiting them.
Regents of the University of California v. Bakke (1978) involved a medical school that reserved 16 of 100 seats for minority applicants. The Court struck down the rigid quota but allowed race to be used as one factor among many in a holistic review.13Justia. Regents of the University of California v. Bakke, 438 U.S. 265 (1978) Justice Powell wrote that a diverse student body is a compelling interest, but reserving a fixed number of slots goes too far.
That framework held for 25 years. In Grutter v. Bollinger (2003), the Court upheld a law school admissions process that treated race as a flexible plus factor inside individualized review rather than mechanically assigning points by race.14Justia. Grutter v. Bollinger, 539 U.S. 306 (2003) The majority also warned that race-conscious admissions should not last forever.
The reversal came in 2023. Students for Fair Admissions v. Harvard ruled that the admissions programs at both Harvard and the University of North Carolina violated the Equal Protection Clause, finding they lacked sufficiently focused and measurable objectives.15Justia. Students for Fair Admissions, Inc. v. President and Fellows of Harvard College (2023) The majority added that “nothing in this opinion should be construed as prohibiting universities from considering an applicant’s discussion of how race affected his or her life, be it through discrimination, inspiration, or otherwise.” Applicants can still write about racial experiences in essays. Admissions offices can no longer treat race itself as a standalone factor.
One boundary worth flagging: the ruling applies to educational institutions receiving federal funding, not to private employers. The EEOC has noted that Title VII already prohibited using race as a “plus factor, a tiebreaker, or a tipping point” long before the Harvard decision, so for workplace hiring the practical impact is limited.16U.S. Equal Employment Opportunity Commission. The Future of DEI, Disparate Impact, and EO 11246 After Students for Fair Admissions v. Harvard/UNC
LGBTQ+ Rights
The clause reached LGBTQ+ rights in Romer v. Evans (1996). Colorado voters had passed a state constitutional amendment barring any local government from enacting anti-discrimination protections based on sexual orientation. The Court struck it down under rational basis review, finding it bore no rational relationship to any legitimate state interest and appeared designed purely to make one group of citizens unequal.17Justia. Romer v. Evans, 517 U.S. 620 (1996) A bare desire to harm a politically unpopular group is not a legitimate government purpose.
The most sweeping decision came in Obergefell v. Hodges (2015), which held that the right to marry is a fundamental liberty protected by both the Due Process Clause and the Equal Protection Clause of the 14th Amendment.18Justia. Obergefell v. Hodges, 576 U.S. 644 (2015) Every state must license marriages between same-sex couples and recognize such marriages performed elsewhere. Justice Kennedy wrote that excluding same-sex couples “demeans” them and “teaches that gays and lesbians are unequal in important respects.” Denying the legal protections of marriage — joint tax filing, inheritance, medical decision-making — solely because of sexual orientation created the kind of second-class citizenship the clause was designed to prevent.19Supreme Court of the United States. Obergefell v. Hodges
Non-Citizens
The 14th Amendment protects “any person” within a state’s jurisdiction, not just citizens. In Graham v. Richardson (1971), the Court held that classifications based on alienage are inherently suspect and subject to strict scrutiny, the same standard used for racial classifications.20Justia. Graham v. Richardson, 403 U.S. 365 (1971) The case struck down state laws denying welfare benefits to lawfully admitted residents who were not citizens.
The rule extends to professional licensing. States cannot bar lawful residents from most professions based on citizenship. The Court struck down a law restricting bar membership to citizens, finding citizenship had nothing to do with the ability to practice law. There is a narrow “political function” exception: states can require citizenship for roles tied to the operation of government itself, such as police officers, probation officers, and public school teachers. When a state tried to bar non-citizens from becoming notaries public, however, the Court found that role too far removed from core government functions to justify the restriction.
Gender Identity
The most actively contested area of equal protection law involves gender identity, which does not yet have a settled standard of review from the Supreme Court.
In June 2025, the Court decided United States v. Skrmetti, a challenge to a Tennessee law banning certain medical treatments for transgender minors. The majority held that the law did not classify on the basis of sex and upheld it under rational basis review, deferring to the state’s judgment in an area of “medical and scientific uncertainty.”21Supreme Court of the United States. United States v. Skrmetti (2025) A concurrence stated that transgender status is not a suspect or quasi-suspect classification, placing it alongside groups like the elderly and people with disabilities that receive only rational basis protection. The dissenters argued the law classified on the basis of sex, since the same medication was permitted for non-transgender minors, and should have received intermediate scrutiny.
One boundary matters here. Bostock v. Clayton County (2020) held that firing someone because of sexual orientation or gender identity violates Title VII of the Civil Rights Act. Bostock was a statutory interpretation case about federal employment law, not a constitutional ruling about equal protection. A person may have a strong Title VII claim for workplace discrimination even where a constitutional challenge under Skrmetti would face only rational basis review.