What amendment was used to justify all types of segregation for decades?

The 14th Amendment, specifically its Equal Protection Clause, was often misinterpreted to justify segregation for decades. Following the Supreme Court's decision in Plessy v. Ferguson (1896), the "separate but equal" doctrine was established, allowing racial segregation to persist under the guise of providing equal facilities. This interpretation of the 14th Amendment facilitated systemic discrimination until it was challenged and ultimately overturned by later rulings, such as Brown v. Board of Education in 1954.