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

Last updated 3 months ago. Our resources are updated regularly but please keep in mind that links, programs, policies, and contact information do change.

Twenty-nine states have passed laws banning transgender girls from school sports. On January 13, 2026, the Supreme Court heard arguments in two cases challenging these bans. The question before the justices is which legal test they will use to evaluate the laws. That choice will decide the outcome.

The framework is called “scrutiny levels.” It’s the constitutional machinery that determines whether laws survive or fall when someone challenges them as discriminatory. Courts don’t treat all classifications the same way. Some get a rubber stamp. Others face a blowtorch.

The Three Scrutiny Standards

When someone challenges a law as discriminatory, courts apply one of three standards. Think of them as different levels of suspicion about what the government is doing.

The most forgiving is the basic reasonableness test. Under this test, a law survives if it makes sense as a way to achieve a valid government goal. The government doesn’t need to prove the law works well, or that it chose the best approach, or even that legislators had this justification in mind when they passed it. Courts will uphold the law if they can imagine any conceivable reason it might be rational. Most laws reviewed this way survive.

At the opposite extreme sits the tough test. Here, the government must prove the law is designed specifically to achieve a necessary government goal, with no unnecessary restrictions. “Compelling” means necessary, of the highest constitutional order. “Narrowly tailored” means the law can’t be broader than necessary to solve the problem. If less restrictive alternatives exist, the law fails. Laws subjected to this standard rarely survive.

Between these extremes lies the middle-ground test, which asks whether a law is directly connected to achieving an important government goal. This is the test applied to sex-based classifications since 1976.

A law banning transgender girls from sports would almost certainly survive the basic reasonableness test. It might survive the middle-ground test depending on the evidence. And it would almost certainly fail the tough test. The choice of test is the ballgame.

Which Classifications Trigger Which Test

The tough test applies to racial classifications, even benign ones designed to help historically disadvantaged groups. It applies to laws that burden fundamental rights like voting or marriage. The premise: some classifications have been so thoroughly weaponized throughout American history that courts must police them with maximum vigilance.

The middle-ground test applies to sex-based classifications. In a 1976 Supreme Court case about Oklahoma setting different drinking ages for men and women, Craig v. Boren, the decision struck down the law. Sex classifications get closer examination because women faced systematic legal discrimination, though the justices have never quite equated sex discrimination with race discrimination.

The basic reasonableness test applies to everything else. Age classifications. Economic regulations. Most government line-drawing that doesn’t implicate groups that have faced discrimination or rights that are especially important.

Nobody knows which test applies to classifications based on gender identity. The justices have never said.

Classification or Regulation: How States Frame the Issue

Idaho and West Virginia—defending the sports bans—argue that their laws don’t classify anyone at all. They’re neutral rules about who can compete in sex-separated athletics, based on biological sex at birth.

This framing matters enormously. If the laws are “classifications”—dividing people into categories and treating them differently—then stricter review might apply. But if they’re merely “regulations” of how sports are organized, applying neutral criteria, then only the basic reasonableness test applies.

United States v. Skrmetti described the Tennessee law as regulating medical treatment rather than sorting people into categories. That reframing allowed the justices to sidestep whether transgender people deserve stronger legal protection against discrimination.

Idaho and West Virginia want to apply the same logic here. A rule saying “girls’ sports are for students of the female sex” presents itself as a neutral organizational principle, not a classification that divides people into groups.

Those challenging these laws argue the opposite. They contend that these particular state laws are sex classifications because their application turns on sex or gender identity. A cisgender girl born female can compete regardless of her gender presentation. A transgender girl born male cannot, even after medical transition. That’s a classification based on sex assigned at birth—exactly what the middle-ground test is designed to police.

Which characterization prevails will likely determine the outcome.

The “Sweeping Assumptions” Doctrine in Sex Discrimination

Even if the justices agree that the sports laws constitute sex classifications subject to the middle-ground test, Idaho and West Virginia could still win. But they’d need to clear a higher bar.

The middle-ground test requires that sex-based classifications be directly connected to achieving an important government goal. Idaho and West Virginia point to fair competition and equal opportunities for female athletes—both important interests. But “directly connected” means more than a rational connection. It means the classification must serve the stated purpose without relying on stereotypical assumptions.

When the justices developed the middle-ground test for sex classifications, they specifically criticized laws that rest on broad assumptions about what men and women are like. Historically, sex classifications were justified by claims about female inferiority, intellectual differences, proper gender roles—assumptions that turned out to be based on stereotype rather than reality.

Modern sex discrimination doctrine insists that government prove the claimed sex differences are real and directly related to the law’s purpose.

Those challenging the bans argue that blanket bans that treat all transgender girls the same rest on a sweeping assumption: that every transgender girl retains significant athletic advantages regardless of medical transition, hormone therapy, or how long ago they transitioned. They contend that categorical exclusion fails to account for individual circumstances, including transgender girls who have undergone hormone therapy or who never experienced male puberty.

The debate illustrates how the middle-ground test works in practice. The question isn’t whether sex differences exist—clearly they do in some contexts—but whether the government is relying on broad assumptions about what those differences mean for particular individuals. Even if differences exist on average, does categorical exclusion of all transgender girls represent an appropriately tailored response?

Under the middle-ground test, that’s a close question. Under the basic reasonableness test, it’s not a question at all.

How Each Test Would Apply to Sports Bans

Under the basic reasonableness test, Idaho and West Virginia win easily. They need only show that sex-separated sports are rationally related to a legitimate interest in fair competition or equal opportunities for female athletes. Athletic performance differences between male and female bodies exist on average. Maintaining separate categories is one way to address these differences. That’s rational. The fact that less restrictive alternatives might exist doesn’t matter—courts don’t demand that government choose the best approach, only a rational one.

Under the middle-ground test, the analysis gets harder. Idaho and West Virginia must prove the blanket bans are directly connected to fair competition. Here the evidence matters. The athletes would present evidence about transgender girls on hormone therapy, about those who never went through male puberty, about the diversity of circumstances that categorical exclusion ignores. The government would present evidence about average physiological differences and competitive fairness concerns.

The justices would have to assess whether blanket bans that treat all transgender girls the same are directly connected to fair competition when less restrictive alternatives exist—case-by-case assessment, hormone therapy requirements, sport-specific regulations. Whether the laws survive the middle-ground test depends on how much weight the justices give to average differences versus individual variation.

Under the tough test, the laws fail. Idaho and West Virginia would need to prove that excluding all transgender girls is designed specifically to achieve a necessary government goal, with no unnecessary restrictions. Fair athletic competition, while important, doesn’t typically qualify as “compelling” in the constitutional sense—that term is reserved for things like national security or preventing discrimination. Even if fair competition counted as compelling, the existence of alternative approaches would doom the laws. The tough test requires the least restrictive means.

What the Skrmetti Decision Signals

Last June’s decision upholding Tennessee’s restrictions on gender-affirming medical care provides the most recent signal about how the conservative majority approaches transgender rights questions.

Chief Justice John Roberts wrote the opinion, joined by the other conservative justices. The majority deliberately avoided whether transgender people deserve stronger legal protection against discrimination. Instead, it characterized the Tennessee law as regulating medical treatment based on age and diagnosis—not classifying based on gender identity.

That reframing proved decisive. By treating the law as a regulation of medical practice rather than a classification of people, the justices applied the basic reasonableness test and upheld the restrictions.

For the sports litigation, Skrmetti offers a roadmap. If the same approach applies, the justices could characterize sports eligibility laws as regulating participation in sex-separated athletics based on biological criteria, not classifying based on gender identity. That would trigger the basic reasonableness test and almost certainly uphold the laws.

Justice Neil Gorsuch, who authored a 2020 decision about employment discrimination extending protections to LGBTQ workers, hasn’t indicated how he views the sports question. Some observers suggest the sports context might be different enough from employment that Gorsuch could allow higher scrutiny, particularly if challengers successfully frame the issue as sex discrimination rather than gender identity discrimination.

Lower courts split on this question. The Ninth Circuit applied stricter review to Idaho’s law and struck it down. The Fourth Circuit did the same with West Virginia’s law. Both found that categorical exclusions violated the laws’ stated purposes of ensuring fair competition, reasoning that blanket bans don’t necessarily accomplish that goal for individuals who have medically transitioned.

Title IX and Federal Education Law

These disputes involve not just constitutional claims but also statutory ones. Challengers argue that the state laws violate Title IX, federal law prohibiting sex discrimination in education.

Title IX’s text prohibits discrimination “on the basis of sex,” but it doesn’t define what “sex” means or whether “sex discrimination” includes discrimination based on gender identity.

A 2020 decision about employment discrimination held that discrimination based on transgender status violates federal law’s prohibition on sex discrimination. But Justice Gorsuch explicitly cautioned that the decision involved only employment and might not apply to other laws. The justices could rule differently on Title IX, treating gender identity classification differently in education than in employment.

Alternatively, they could hold that even under Title IX’s sex discrimination prohibition, categorical exclusion based on biology isn’t sex discrimination because the laws apply neutral rules about biological sex. They might find that Title IX permits sex-separated athletics and that maintaining separate categories based on biology doesn’t constitute sex discrimination, even if it affects transgender and cisgender students differently.

Broader Implications Beyond Sports

The decision—expected in late June 2026—will ripple far beyond school sports.

A ruling that gender identity classifications don’t trigger stricter review, or that discrimination based on gender identity doesn’t constitute sex discrimination, would open the door to much broader restrictions. Lawmakers have already begun using sports restrictions as entry points for more limitations on access to bathrooms, locker rooms, and other public places like restaurants, stores, and gyms. A signal from the justices that such discrimination doesn’t warrant stronger constitutional protection would encourage lawmakers to pass more expansive restrictions.

Conversely, a ruling that discrimination based on gender identity triggers stricter review or constitutes sex discrimination would provide powerful protection across multiple contexts.

The justices could also issue a narrow ruling: allow sex-separated athletics as constitutionally permissible while declining to answer the broader question of whether gender identity classifications warrant stricter review. Such a narrow ruling would let Idaho and West Virginia win without providing broader precedent about transgender rights.

The choice of scrutiny level will determine how vigilant courts will be in protecting transgender people from discrimination going forward. It will affect how courts interpret constitutional law, shaping how judges evaluate discrimination in employment, housing, healthcare, education, and public places.

What Scrutiny Levels Reveal About Constitutional Values

Scrutiny levels aren’t technical legal doctrine. They’re the mechanism through which courts decide how much to trust lawmakers when constitutional rights are at stake.

The framework embodies a judgment about which groups have been historically vulnerable to discrimination and thus deserve heightened judicial protection. When the justices apply the tough test to racial classifications, it reflects a constitutional judgment that race has been weaponized as a tool of oppression. When they apply the middle-ground test to sex classifications, it acknowledges that women have faced systematic legal discrimination. When they apply the basic reasonableness test to age classifications, it reflects a judgment that age hasn’t been used quite the same way.

The choice of scrutiny level for gender identity classifications will signal whether transgender people constitute a group deserving stronger constitutional protection, or whether discrimination against them is another policy choice entitled to judges giving lawmakers the benefit of the doubt.

When the decision arrives in June, the choice of analytical framework—classification or regulation, tough test or basic reasonableness test, sex discrimination or something else—will determine the trajectory of civil rights law.

Our articles make government information more accessible. Please consult a qualified professional for financial, legal, or health advice specific to your circumstances.