The 14th Amendment contains the Equal Protection Clause which aims to prevent discrimination against certain classes of individuals. The Supreme Court has different levels on determining if a law has infringed upon the rights of an individual (or group) under the 14th Amendment. These levels are:

Strict Scrutiny

For a law to pass strict scrutiny, the legislation must have a compelling state interest that is done though the least restrictive means. Most laws do not pass strict scrutiny as both parts have very high standards to pass. Examples of compelling state interests include national security and fighting racial discrimination. Even if there is a compelling state interest, the government must prove that the law is the least restrictive way to achieve the interest. If not, the court would have to strike down the law. Classes that fall under strict scrutiny include race, national origin, religion and alienage. Also, laws that target essential rights, such as the right to vote, are examined under the strict scrutiny framework.

Intermediate Scrutiny

Unlike strict scrutiny, a classification that falls under intermediate scrutiny has a lower overall threshold to justify a law that affects the class. The law must have an important (rather than compelling) state interest and must be substantially related to achieving the interest. Gender is a well known classification that falls under intermediate scrutiny protection. Gender was classified under the immediate scrutiny test in the case Craig v. Boren which invalidated a state law that implemented unequal alcohol purchasing ages.

Rational Basis

The lowest standard for a law to pass under an equal protection challenge is the rational basis test. A law must have only a legitimate interest, and that the law rationally undertakes that interest. Classifications that fall under this test include mentally challenged people, LGBT, children of illegal aliens, etc. LGBT advocacy groups have challenged the inclusion of the group under the rational basis test and pointed to the 2015 case Obergefell v. Hodges to indicate a shift to the strict scrutiny test. However, other legal analysts point out that the case was just a legal victory for same-sex couples without actually commenting on whether the group was under a new classification.