Magna Carta exercised a strong influence both on the United States Constitution and on the constitutions of the various states. ... Magna Carta was widely held to be the people's reassertion of rights against an oppressive ruler, a legacy that captured American distrust of concentrated political power.
Slavery in it's most basic sense is where property rights are applied to people, so the black slaves during that time were not paid as they were seen as equal to cattle or livestock.
