Often plate boundaries move in such a way that the crust is neither created nor destroyed, what type of force is this

in plessy v. ferguson in 1896, the u.s. supreme court ruled that racially separate facilities, if equal, did not violate the constitution. segregation, the court said, wasn't discrimination.

in brown v. board of education, the court overturned plessy v. ferguson, and declared that racial segregation in public schools violated the equal protection clause of the 14th amendment.