Roman Republic
Slavery and slaves were part of the social order; there were slave markets where they could be bought and sold. Many slaves were freed by the masters for services rendered; some slaves could save money to buy their freedom. Generally, mutilation and murder of slaves was prohibited by legislation. However, Rome did not have a law enforcement arm. All actions were treated as "torts," which were brought by an accuser who was forced to prove the entire case himself. If the accused were a noble and the victim, not a noble, the likelihood of finding for the accused was small. At most, the accused might have to pay a fine for killing a slave. It is estimated that over 25% of the Roman population was enslaved.

Q: Were slave masters allowed to free their slaves in the Roman Republic?
Many slaves were freed by the masters for services rendered