Who cares for left or right as long as it's the best way and more people live a good life? So stop talking divisions focus on the justice like in "just" here.
Briefly, left-wing folks think that it's best when everybody is equal, right-libertarians think it's best when everybody is free, and the Catholic Church and other religious types think it's best when everybody does what God says.
"Fair and proper administration of laws conforming to the natural law that all persons, irrespective of ethnic origin, gender, possessions, race, religion, etc., are to be treated equally and without prejudice. See also civil rights." http://www.businessdictionary.com/definition/social-justice....