Ancient Rome

In the Roman Republic and the Early Roman Empire about 15% to 20% of the population were slaves, and - until the 2nd century when laws protecting slaves were instituted - a master could legally kill a slave. However this seems to have been a somewhat rare occurrence, for complex social reasons. In any event, the Cornelian Law in 82 BCE forbade masters from killing a slave; the Petronian Law in 32 BCE forbade masters from compelling slaves to fight in the arena. Suetonius wrote (Claudius, 25) that, under Emperor Claudius, if a master neglected the health of his slave, and the slave died, the master was guilty of murder; furthermore, if the slave recovered in a temple of Asclepius, he should be freed. Dio Chrysostom, a Stoic Greek under Emperor Trajan, devoted two Discourses (14 and 15), delivered over two days at the Forum, to the condemnation of slavery. Seneca the Elder (in De Clementia or "On Mercy," 1:18), in the first century CE, records that masters who were cruel to their slaves were publicly insulted. Hadrian, in the second century CE, renewed the Cornelian and Petronian laws. Ulpian, a Stoic lawyer of the third century CE under Emperor Caracalla, made it illegal for parents to sell their children into slavery. The last notable pagan Emperor, Diocletian, in the late third and early fourth century CE, made it illegal for a creditor to enslave a debtor and for a man to sell himself into slavery to pay a debt.

Vedius Pollio, a citizen of Rome, reportedly fed the bodies of his slaves to his pet fish. Flavius Gratianus, a fourth-century Roman emperor who favored Christianity, ruled that any slave who accused his master of a crime should be immediately burned alive, but this applied mostly to plots against the emperor's own life. Roman slaves who participated in revolts were often crucified.

In ancient Greco-Roman times, slavery was related to the practice of infanticide. Unwanted infants were exposed to nature to die; these were then often rescued by slave traders, who raised them to become slaves. Justin Martyr, in his First Apology, defended the Christian practice of not exposing infant only secondarily because the child might die; first of all,

But as for us,we have been taught that to expose newly-born children is the part of wicked men; and this we have been taught lest we should do any one an injury, and lest we should sin against God, first, because we see that almost all so exposed (not only the girls, but also the males) are brought up to prostitution.