One way which this belief "that all men were created equal and had natural rights that could not be taken away" was enforced in the early U.S. can be seen through the ending of slaving, slaves had no civil rights before it, some were not even considered human and had no right to freedom or their own life at all; or it can be seen in the giving of the right to vote for men that were poor too, or women and black people, before only rich or white men could vote.
