How the Supreme Court Decides Equal Protection Cases: Scrutiny Levels, Explained

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In 1996, in United States v. Virginia, the Supreme Court rejected Virginia’s attempt to keep the Virginia Military Institute all male. Virginia had drawn a line between men and women, and the Constitution’s Equal Protection Clause required the state to justify it.

How strong the justification must be depends on which of three tests, called levels of scrutiny, a court applies: rational-basis review, intermediate scrutiny or strict scrutiny. The level sets how important the government’s goal must be and how closely the rule must fit it, but it does not decide the case by itself.

Different treatment is the beginning of the question

The Fourteenth Amendment’s Equal Protection Clause directs states to treat people in similar situations alike. The federal government has equal-protection obligations through the Fifth Amendment.

A legal classification, meaning a distinction between groups, does not by itself invalidate a law. The question is why the law draws the distinction and whether that reason justifies the different treatment.

Rational-basis review permits distinctions that reasonably relate to a legitimate government interest. A court applying that test asks whether the Constitution permits the law, not whether legislators chose the wisest policy.

A law that is neutral on its face, meaning its text draws no racial line, is not unconstitutional solely because it has a racially disproportionate impact; there must also be a discriminatory purpose. Disproportionate impact remains relevant, but it is not the sole test, and standing alone it does not trigger strict scrutiny, the most demanding of the three tests.

The three tests, side by side

The three levels differ in two ways: how strong the government’s objective must be, and how closely its rule must be connected to that objective.

Narrow tailoring means the government must shape its rule specifically and closely to the compelling purpose it claims to serve.

Under ordinary rational-basis review, a classification is presumed valid, and the challenger must rule out every conceivable basis that could support it. The justification need not be the reason legislators actually had in mind. That gives lawmakers room to draw imperfect lines, even when a more precise policy seems possible.

When a law classifies by sex, the burden of justification is on the state. It must show at least the important objective and the substantial relationship, and its justification must be genuine, not one invented after litigation begins. The shift is from giving a conceivable explanation the benefit of the doubt to requiring the government to defend the distinction it actually made.

Strict scrutiny, the test for racial classifications, allows them only if they are narrowly tailored measures that further compelling government interests. The Supreme Court has expressly rejected the idea that strict scrutiny inevitably invalidates the government’s action. In United States v. Paradise, decided February 25, 1987, the Court upheld a temporary promotion remedy requiring Alabama’s state police to promote one qualified Black trooper for each white trooper while it developed acceptable promotion procedures. A four-justice plurality concluded that the remedy survived even strict scrutiny because it was narrowly tailored to remedy the department’s discrimination. Justice O’Connor dissented, arguing that the remedy was not narrowly tailored enough.

What puts a law under stricter review

Government racial classifications receive strict scrutiny whether imposed by federal, state or local government. The standard applies regardless of the race of those burdened or benefited.

Sex classifications receive the heightened review described above, which the Court calls intermediate scrutiny. The rule does not make every distinction involving sex forbidden, but it requires more than an ordinary plausible explanation.

Equal-protection decisions also protect against differential treatment in exercising fundamental rights, including voting and entry into marriage. A rule that significantly interferes with the right to marry requires close examination of the state’s justification. In Zablocki v. Redhail, the Court also explained that reasonable regulations that do not significantly interfere with the decision to marry may be imposed. The analysis is consequently broader than a checklist of groups: it also asks whether the government’s line interferes with a protected right.

Courts sort classifications of people with two labels. A suspect classification, such as race, is subject to strict scrutiny; a quasi-suspect one calls for a more exacting standard of review than ordinary laws receive. Age is not a suspect classification, and an age distinction that does not burden a fundamental interest receives rational-basis review. The Supreme Court also declined to treat intellectual disability as a quasi-suspect classification in City of Cleburne v. Cleburne Living Center, a 1985 case described below.

State distinctions based on alienage, or noncitizenship, generally receive strict scrutiny. But some state rules tied to self-government and the democratic process, typically for positions that involve policymaking or authority over others, need only satisfy rational-basis review. Federal alienage classifications generally receive more deferential review than state classifications. Who made the distinction and what function it serves can therefore matter alongside the category itself.

Why the fit between the rule and its goal matters

In Craig v. Boren, decided December 20, 1976, Oklahoma prohibited sales of 3.2 percent beer to men under 21 and women under 18. The distinction treated sex as a shortcut for deciding which young adults could buy the beer.

The Supreme Court found the sex differential unconstitutional because the statistics did not establish sex as an accurate proxy for regulating drinking and driving. The problem was the connection between the category and traffic safety, not whether traffic safety mattered.

United States v. Virginia, decided June 26, 1996, concerned the all-male Virginia Military Institute, a public college training citizen soldiers. The Supreme Court required an exceedingly persuasive justification for gender-based government action. Meeting that burden, the Court said, takes at least the important objective and substantial relationship described above.

The Court rejected the use of fixed notions about men’s and women’s abilities to exclude qualified individuals. Virginia’s proposed separate program for women was different in kind and unequal in facilities, and did not offer VMI’s rigorous military training. A substitute opportunity had to address what qualified women had actually been denied, rather than merely give them a separate institution.

In Cleburne, decided July 1, 1985, a Texas city denied a special-use permit for a group home for people with intellectual disabilities. The Supreme Court found that other permitted uses faced no comparable restriction and that the permit requirement rested on irrational prejudice. The city lost under rational-basis review, which shows that even the most deferential test does not make every government explanation sufficient.

Two recent rulings: choosing the test, then applying it

In United States v. Skrmetti, decided June 18, 2025, the Supreme Court addressed Tennessee restrictions on puberty blockers and hormones for minors seeking transition-related treatment. Asked to apply heightened scrutiny, the majority instead identified classifications based on age and medical use and applied rational-basis review. The Court held that the restrictions satisfied that review, affirming the judgment by a 6 to 3 vote.

The challengers, three transgender minors, their parents and a doctor, argued that the law discriminated based on sex and transgender status. Justice Sotomayor’s dissent, joined on the sex-classification issue by Justices Kagan and Jackson, argued that the law’s use of a patient’s sex to determine which treatments were permitted required intermediate scrutiny.

Skrmetti did not resolve whether transgender status itself is a suspect class, because the majority concluded that the law does not classify on that basis. The ruling therefore rests on the classifications the majority found in that law; it does not say that every dispute involving transgender people gets the same test.

The Supreme Court’s school-sports ruling, West Virginia v. B.P.J., decided June 30, 2026, asked whether schools may reserve women’s and girls’ sports teams for “biological females,” the Court’s term. The ruling covered challenged laws from West Virginia and Idaho, and the majority found that both made sex-based classifications. It concluded that limiting women’s and girls’ teams to biological females was substantially related to the important interests of safety and competitive fairness. The states therefore won under intermediate scrutiny, not because the Court found no sex classification.

The majority held that satisfying intermediate scrutiny did not require an athlete-by-athlete comparison of physical and athletic capabilities. B.P.J., a transgender girl seeking to join her school’s girls’ cross-country and track teams, had challenged West Virginia’s law. The Fourth Circuit had ruled for her on Title IX and sent her equal-protection claim back for more fact-finding. The Court reversed the lower-court judgment in the West Virginia case and sent it back. Justice Sotomayor, joined by Justices Kagan and Jackson, agreed that B.P.J.’s Title IX claim failed on a narrower ground, but dissented on equal protection. B.P.J. argued that girls like her who had not experienced male puberty and received treatment lacked the athletic advantage the state asserted. The dissent would have allowed further fact-finding on that disputed premise before deciding whether the exclusion fit the state’s safety and fairness goals. The VMI decision and the sports ruling applied the same test and came out differently: one rejected excluding qualified women on generalizations, the other upheld a sex-based rule without athlete-by-athlete exceptions.

Equal protection is a constitutional claim; civil rights statutes are a separate source of protection, and a result under one does not automatically settle the other. Title IX of the Education Amendments of 1972 prohibits sex discrimination in education programs and activities receiving federal financial assistance. Title VII of the Civil Rights Act of 1964 prohibits employment discrimination based on race, color, religion, sex or national origin.

In the sports ruling, the Court separately held that Title IX allowed teams defined by biological sex and that West Virginia acted consistently with that statute. Title VII mattered in Skrmetti because Bostock v. Clayton County had held that firing someone for being gay or transgender violates Title VII. The Skrmetti majority declined to decide whether Bostock’s reasoning extended beyond employment law, concluding that changing a minor’s sex or transgender status would not change how Tennessee’s treatment restriction applied. Justice Thomas’s concurrence separately argued that Title VII and the Equal Protection Clause use different language.

How to read a ruling about one person or one law

A facial challenge asks a court to assess a law’s constitutionality without regard to its impact on the challenger. An as-applied challenge concerns the law’s application to a specific person, based on a factual record. That distinction is about the scope of the challenge, not the level of scrutiny.

In Cleburne, the Supreme Court invalidated the zoning ordinance as applied to the proposed home. The Court rejected that use of the ordinance; it did not strike down the entire zoning rule. An as-applied argument can also lose, as the sports majority’s rejection of individual-exception arguments demonstrates.

A claim also needs a route into court: Section 1983, a federal statute, allows a civil suit over the deprivation of federal rights by someone acting under color of state law. Acting under color of state law means acting, or claiming to act, in official duties under state, county or municipal law. That statute is a way to bring a claim, not a guarantee that the challenged distinction is unconstitutional.

When reading an equal-protection decision, ask in order: which groups are being compared, which level of scrutiny applies, what objective the government claims, how closely the rule fits it, and how far the ruling reaches. Read the conclusion as an answer to those questions, not as a general declaration that government may always, or never, treat the groups differently.