The thirteenth amendment states that slavery is no more, so an example of this could just be society how it currently is, I guess.
The Supreme Court can declare presidential acts unconstitutional.
Generally speaking, for a development such as this to be considered a civilization, there must be some form of government, which regulates to a certain extent the lives of the citizens.
You allready got the answers to this
Prince Henry the Navigator opened a school for navigation where he lived which was Portugal
