The judicial branch checks that all laws are constitutional
A.) Rwanda. I can not explain exactly why this took place in Rwanda but they even have a movie on the conflict between the Tutsi and Hutu tribes. Everything in the movie took place in Rwanda.
Mostly likely no. He could've done more. If he had done more there probably wouldn't be a need for the civil rights act of 1964.
Convection in the mantle is the answer
Its not that we allow it it just happens and noone can say anything about it even though its wrong