The Equal Protection Clause is part of the first section of the Fourteenth Amendment to the United States Constitution. The clause, which took effect in 1868, provides "nor shall any State ... deny to any person within its jurisdiction the equal protection of the laws." It mandates that individuals in similar situations be treated equally by the law.

A primary motivation for this clause was to validate the equality provisions contained in the Civil Rights Act of 1866, which guaranteed that all citizens would have the guaranteed right to equal protection by law. As a whole, the Fourteenth Amendment marked a large shift in American constitutionalism, by applying substantially more constitutional restrictions against the states than had applied before the Civil War.

The meaning of the Equal Protection Clause has been the subject of much debate, and inspired the well-known phrase "Equal Justice Under Law". This clause was the basis for Brown v. Board of Education (1954), the Supreme Court decision that helped to dismantle racial segregation. The clause has also been the basis for Obergefell v. Hodges which legalized same-sex marriages, along with many other decisions rejecting discrimination against, and bigotry towards, people belonging to various groups.

While the Equal Protection Clause itself applies only to state and local governments, the Supreme Court held in Bolling v. Sharpe (1954) that the Due Process Clause of the Fifth Amendment nonetheless imposes various equal protection requirements on the federal government via reverse incorporation.