The Equal Protection Clause and Tiers of Scrutiny

The Equal Protection Clause of the Fourteenth Amendment says no state can deny any person equal protection of the laws. But every law classifies somebody: speeders get tickets, 16-year-olds get licenses, veterans get benefits. The question is never whether a law treats people differently. It's whether the difference is justified. Courts answer that with tiers of scrutiny, each one a hurdle of a different height that the government must clear.

Rational basis review is the low hurdle. Government just needs a legitimate interest and a rational connection between the classification and that interest, and courts imagine reasons even if the legislature never stated one. This is where ordinary classifications land: age for a license, income for a tax bracket. Strict scrutiny is the high hurdle, reserved for race and national origin, and sometimes religion. Government must show a compelling interest and that the law is narrowly tailored, the least restrictive way to achieve it. Most laws here fail. Intermediate scrutiny sits between the two, applied to sex-based classifications: government needs an important interest and a substantial relationship between the law and that interest.

The tier is decided entirely by the classification, not by how serious the law feels. A law banning interracial marriage uses a racial classification, so it faces strict scrutiny and falls, as in Loving v. Virginia in 1967. A law setting different drinking ages for men and women uses a sex classification, triggering intermediate scrutiny. A law setting a driving age of 16 uses an age classification, an ordinary one, so it only needs rational basis. This same logic connects outward to how the Court has incorporated other rights against the states, one classification and one case at a time.