What Couldn’t Owners Do to Slaves in Ancient Rome?

When we think of slavery in ancient Rome, the common assumption is that masters had total unchecked control over their slaves. That they could make them do anything, punish them in any way, torture them, or even kill them without facing any consequences. And to be honest, that assumption isn’t too far off. Under Roman law, slaves were considered property, not people, but speaking tools. Still, it would be an oversimplification to say that every master could do absolutely anything to any slave at any time with zero repercussions.

So, let’s take a closer look at what actually limited a master’s power, what those restrictions were, how they worked, and when they came into play. After all, slavery in Rome spanned more than 12 centuries, and the conditions of slaves in the Roman state varied greatly over time. According to the Greek historian Dionysius of Halicarnassus, Romulus, Rome’s first king and legendary founder, allowed citizens to sell their own children into slavery. This suggests that slavery existed in Rome from the very beginning of the city’s history. But over the next 1,200 years, both the legal status of slaves and the laws that governed them evolved significantly.

In the beginning, Rome was nothing more than a small, modest town. Rome’s population was small in its earliest days, and the number of slaves was even smaller. During the monarchy and the early Republic, economic inequality wasn’t especially stark. Even the wealthiest Romans were usually landowners who worked the fields themselves, often alongside just a handful of slaves. This made the relationship between master and slave more personal and at times surprisingly friendly. It’s much harder to be cruel to someone you labor beside every single day.

Of course, that closeness also came with risks. A master who pushed too far might find himself on the receiving end of a hoe to the back of the head. In the late Republican Empire, escape wasn’t much of an option for a slave. There was simply nowhere to run. Rome was everywhere. But during early Roman history, it wasn’t so. The nearest neighboring tribe or settlement was only a half a day’s walk away. It was easy for a slave to disappear and impossible to track them down. That’s one reason slave owners in early Rome tended to treat their slaves relatively leniently.

But as Rome’s territory expanded and wars brought in wave after wave of prisoners, the dynamic shifted. By the fifth century B.C., slaves made up roughly 20% of the Roman population and had become essential to the economy. From that point forward, the treatment of slaves steadily deteriorated. During the entire Republican era, there were no legal limits on a master’s authority over their slaves. In reality, Roman masters could treat their slaves however they pleased. The only faint hope for protection came from the censors, powerful officials who had the authority to enter any household, intervene in cases of excessive cruelty, and even punish the master.

But it’s important to understand that this power was a right, not a duty. Censors weren’t investigators, and they didn’t routinely check up on how slaves were being treated. Slaves themselves had no legal standing to appeal to a censor, so they couldn’t ask for help. Only a free citizen could report abuse, and even then, a censor could choose to ignore the complaint entirely. On top of that, the office of censor wasn’t permanent. Censors were elected only once every 5 years, and they served for just 18 months. That meant that there were stretches of 3 and a half years with no censors at all, no officials who could intervene even in theory. And during the more than 400 years between the creation of the censor’s office and the rise of the Roman Empire, we don’t have a single recorded case of a censor stepping in to protect a slave. That doesn’t mean that it never happened, but it strongly suggests that it was incredibly rare.

During the imperial era, there are two well-known cases where an emperor who also had censorial powers personally stepped in to protect a slave. The first took place at a banquet hosted by the equestrian Vedius Pollio. When one of his slaves accidentally broke an expensive crystal goblet, Pollio, enraged, ordered the man to be thrown into a tank of lampreys as punishment. Emperor Augustus, who was present, intervened. He not only spared the slave’s life, but granted him freedom, and as a final rebuke, ordered all the remaining crystal goblets in the house to be smashed in front of Pollio.

In the second case, Emperor Hadrian exiled a Roman matron named Umbricia from the city for 5 years after she brutally beat a slave girl over a trivial matter. These were rare instances, but they highlight a key reality. While censors and emperors technically had the authority to protect slaves, they almost never exercised it unless the violence was public and impossible to ignore.

Around the turn of the era, a handful of new laws began to offer slaves minimal legal protection and place some limits on a master’s unchecked cruelty. In 4 B.C. and 2 B.C., the Lex Aelia Sentia and Lex Fufia Caninia were passed to regulate manumission, restricting how many slaves could be freed at once, especially by will. Later, under Emperor Claudius, a law was introduced stating that if a master abandoned a sick slave and the slave managed to recover without assistance, that slave would automatically be granted their freedom. The master was also responsible for burying their slave. If they refused to do so, anyone else could carry out the burial and then sue the master to recover the expenses.

In 61 A.D., the Lex Petronia prohibited owners from sending their slaves to be torn apart by wild animals without a judge’s approval. Emperors Domitian and later Hadrian banned the castration of slaves. In 161 A.D., Emperor Antoninus Pius prohibited the unjustified killing of slaves. A master who was found guilty of deliberately killing their own slave was held to the same legal standard as if they had killed someone else’s slave. Such an owner could be fined and was also required to pay the value of the murdered slave.

In 319 A.D., Emperor Constantine’s law went even further, equating the killing of a slave with the murder of a free person. However, both Constantine’s and Antoninus Pius’s laws held the master accountable only if the killing was intentional. For example, if the slave was stabbed with a dagger, hanged, thrown from a great height, or fed to wild beasts. On the other hand, if a slave died as a result of punishments that were considered normal in Roman society, such as being beaten to death with whips, the law placed no blame on the master.

In addition to laws that offered slaves a minimal degree of protection, classical Roman law also included four standard clauses that could be added to a contract for the sale of a slave. One such clause, ne manumittatur, prohibited the buyer from freeing the purchased slave. This condition could be added at the seller’s request for a variety of reasons. For instance, when selling an elderly slave, the seller might include this clause to prevent the slave from being freed, ensuring that they would at least have some minimal care and support in old age. Since masters were legally required to provide for their slaves, many elderly slaves who could no longer work were simply freed to reduce the burden. On the other hand, a seller might include the ne manumittatur clause, a ban on manumission, if they believed the slave didn’t deserve freedom.

By contrast, the ut manumittatur clause required the buyer to free the slave after a set period of time as specified in the sale contract. The ut exportatur clause obligated the buyer to remove the slave from a specific city or region and barred them from bringing the slave back. In some cases, even if the slave was later freed, returning to that area could result in reinslavement. Finally, the ne serva prostituatur clause explicitly prohibited the buyer from forcing a female slave into prostitution.

These clauses remained legally binding even if the slave was resold. For instance, if a buyer purchased a slave girl and later sold her without disclosing the ne serva prostituatur clause and the new owner forced her into prostitution, the courts could intervene. In such cases, the slave would be granted her freedom and legally become a freedwoman under her original seller. Interestingly, there were no equivalent clauses restricting a slave’s use in other professions. Only prostitution drew this level of legal attention.

In early Roman law, the penalties for violating these clauses were typically laid out in the contract itself. For example, breaking the ne serva prostituatur clause could result in a fine, the return of the slave to her previous owner, or immediate manumission. Under Emperor Constantine, this clause was eventually standardized. If violated, the slave was automatically freed and her legal patron would be her original seller.

So, while a few laws in the Roman Empire imposed limited restrictions on a master’s cruelty, the reality of slavery remained brutally harsh. Roman legal commentaries made it clear that these rules weren’t motivated by concern for the slave’s well-being. They were designed to prevent unrest and preserve public order. And the most effective legal protections like ne manumittatur or ut manumittatur weren’t universal. They applied only when a previous owner took the initiative to include them in a sale. Most slaves had no such safeguards. Even in its most progressive moments, Roman law treated slaves not as human beings, but as tools. And the few rules it did enforce were simply there to stop owners from breaking those tools unnecessarily.

Ultimately, looking back across the centuries, the evolution of Roman slavery reveals a stark truth about the civilization. No matter how much the empire expanded, built magnificent monuments, or codified its laws, the foundational pillar of its society rested on the subjugation of the human spirit. The legal tweaks and rare imperial interventions were merely ripples on the surface of a deeply oppressive ocean. As the Roman world rose and eventually fell, the quiet suffering of countless anonymous individuals remained the hidden engine driving its grand history forward.