Justice is a universal moral concept. It isn't specific to any particular legal system. Rather, humans devise legal systems which live up to the ideals of justice (or fail).
Teaching the class, maybe.The KKK was created by Southern Democrats. You may want to go back to history class.
Party =/= Ideology. Republican Party lost interest in progressivism and started appealing to conservatives in order to get the numbers in needed to remain a viable national level party and the Democratic Party went left when blue collar start liberalizing due to Unions. Civil Rights Movement put the boot in the old superstructure.