Social Justice could be considered and extension of Social Media but because it pertains to a particular type of Social Media should be considered uniquely by it's own definition:
"Social Justice is the use of the Internet through unique websites to report or file claims against business's or people who act in an unethical, illegal, or unprofessional manner. Social Justice uses the power of the Internet to provide the general public with a way to determine these types of business's and/or persons that act in a way consumers or the public should be aware of."