https://www.law.cornell.edu/constitution/amendmentxiv
14th Amendment | U.S. Constitution | US Law
The Fourteenth Amendment addresses many aspects of citizenship and the rights of citizens. The most commonly used — and frequently litigated — phrase in the amendment is “equal protection of the laws”, which figures prominently in a wide variety of landmark cases, including Brown v. Board of Education (racial discrimination)

https://www.britannica.com/topic/equal-protection
Equal protection | United States law | Britannica
equal protection, in United States law, the constitutional guarantee that no person or group will be denied the protection under the law that is enjoyed by similar persons or groups. In other words, persons similarly situated must be similarly treated.