The Equal Protection Clause is part of the Fourteenth Amendment to the US Constitution, ratified in 1868.

The Equal Protection Clause prohibits states from denying any person within their jurisdiction the equal protection of the laws.

In 1873, the Supreme Court ruled in the case of Slaughter-House Cases that the Equal Protection Clause did not apply to state laws that discriminated against businesses.

In 1896, the Supreme Court ruled in Plessy v. Ferguson that states could maintain separate but equal facilities for different races, as long as the facilities were substantially equal.

In 1954, the Supreme Court ruled in Brown v. Board of Education that racial segregation of public schools was unconstitutional, overturning the "separate but equal" doctrine.

The Equal Protection Clause of the Fourteenth Amendment has been interpreted to prohibit discrimination based on sex, although there is no explicit mention of sex in the Amendment itself.

In 2015, the Supreme Court ruled in Obergefell v. Hodges that the fundamental right to marry is guaranteed to same-sex couples by both the Due Process Clause and the Equal Protection Clause.

Under strict scrutiny, a law that discriminates on the basis of race or national origin must be narrowly tailored to achieve a compelling government interest.

Under intermediate scrutiny, a law that discriminates on the basis of sex or gender must be substantially related to an important government interest.

Under rational basis review, a law that does not discriminate on the basis of a suspect classification must be rationally related to a legitimate government interest.

A law that creates a separate but equal school system for different races would be subject to strict scrutiny because it discriminates on the basis of race.

A law that prohibits discrimination in employment on the basis of sex would be subject to intermediate scrutiny because it discriminates on the basis of sex.

A law that regulates the sale of alcohol would be subject to rational basis review because it does not discriminate on the basis of a suspect classification.

The Equal Protection Clause has been used to strike down laws that discriminate on the basis of race, color, religion, sex, and national origin.

The Equal Protection Clause has contributed to the advancement of civil rights in the United States by prohibiting discrimination, establishing the principle of equal protection, leading to desegregation, and ensuring equal access to opportunities for all Americans.