Would Brown v. Board of Education and Loving v. Virginia have still been decided the same way in a scenario where the original US Constitution (as in, the 1787 text) explicitly states that US states are allowed to segregate their schools by race and to have anti-miscegenation laws?
FTR, I know that this scenario is unrealistic, but it's not completely ASB. Basically, I want to know if SCOTUS would have still decided its two most legendary rulings in the same way had things such as school segregation and anti-miscegenation laws been explicitly sanctioned by the original US Constitution.
Well, aside from a POD in 1787 likely meaning 1954 and 1967 cases as we know them wouldn't occur...
It wasn't the original constitution that struck down those laws. It was the 14th amendment, which applied the bill of rights to the states.
On interracial marriage, following the civil war northern and southern Republican governments and judges repeatedly dealt with the question in court cases and state constitutional conventions. They repeatedly shot it down on the grounds of constitutionality and because they thought it was bad policy (either due to violation of free association, because they figured it was kind of a moot point because nobody socially approved of it anyway, or because they thought that a lack of a ban made interracial relationships
less likely because it meant more social enforcement of racial norms).
School segregation is harder. The same Congress that passed the war amendments also was the one that established segregated schools in Washington DC. The Fusionist and Readjuster governments of North Carolina and Virginia respectively didn't bother to try pushing for school integration. Of course, modern schooling also just wasn't a thing in 1787 and there's a fair argument that even if what counted as schooling in 1787 could be segregated the modern government service that is schooling is a very very different animal.
OTL pre Brown v Board the argument made by Thurgood Marshall and the NAACP was leaning towards supporting the doctrine of separate but equal. To clarify, they said that it was doctrinally fine but practically impossible (ergo any separation would by default result in inequality). Even if segregation on the basis of race were allowed constitutionally, the court may find that due to the complete inability for the government to provide equal level of service to all of its citizens in a segregated circumstance, segregation cannot continue in schooling.