Societies should have rules and laws so that everyone can have a basic understanding of legal right and wrong. This way people know where the line is drawn on their actions. The difference between rules and laws, are that while rules may be dictated on solely social means, laws are held to a legal standard with legal punishments for breaking them.
Well if we are talking about voting rights and equality, that would be Martin Luther King. He set equality for black people while Abraham Lincoln had just freed them decades earlier.