Somewhat unique to Rawls' theory of justice is that there is a large spectrum of factors that must be accounted for. People are equal and deserve as much liberty as possible, but everyone gets the same amount. Liberties cannot violate others' right to liberty. Everyone should have equal footing in the political arena. This is mainly to guard against an autocratic society.
Examples are health, intelligence, physical talents, etc.
Most people consider John Rawls' theories on justice to provide a social contract. This is really a misnomer if you look to the facts. In order for a government to be just, it must fulfill his two principles of government, but there are several forms of government that can do just that. Socialism, communitarianism, democracy, liberty, and many more can be just, so long as they fulfill Rawls' two principles. From an LD debater's perspective, this can be good or bad.