Why were these two systems put into place in the Middle Ages during Western Europe? (What caused or what forced feudalism and manorialism to develop)

Me a slaveowner who worked a slave to death or be a slave to death, a. cannot be tried for murder in criminal court but could be sued for wrongful death in the civil court b. cannot be tried in court because there was no law against the mistreatment of slaves. c. could have his form or plantation confiscated by the state and sold to the highest bidder. d. could be tried for murder in most southern states.