Historians disagree as to the actual date that the Lex Aquila (also Anglicized and known as the Aquilian Law) was promulgated into Roman law, some saying as early as 487 BC, whereas most give it a date of 286 BC, which makes more sense because the Lex Aquila purports to displace, in part, the Law of the Twelve Tables, a document that is not believed to have been created until about 450 BC.

Although the original Lex Aquila text spoke only of compensation for injury to slaves or livestock, the principle of monetary compensation for harm done had sprung to life in the garden of law.

The Lex Aqulia refined the very basic and rudimentary rules of law in regards to unlawful or accidental damages caused to others.

Roger as Roman CenturionIn the Twelve Tables, punitive or retaliatory action such as injuries or death to the tort-feasor were the rough and ready solution to personal injury or debt. For example, Table VIII:

"If one has maimed a limb and does not compromise with the injured person, let there be retaliation."

In Justinian's Institutes, Book IV, the Aquilian law is called the Aquilian Act and is summarized as follows:

"If anyone wrongfully kills another's slave, male or female, or another's livestock (quadruped), he must pay the owner the highest value which the thing had in that year."

By the time of Justinian's the seamstresses of Roman law, such as Gaius, Ulpian and Tribonian read into the basic Lex Aquila this extract from the Institutes of Justinian:

"Even one who kills by accident escapes liability ... if not at fault."

Lex Aquila sought to provide a more sophisticated resolution to these events, more amenable to commerce.

The Lex Aquila formed the basis for the later development of civil responsibility in Roman law and its successor, civil law. Lex Aquila is said to be the founding document of modern tort and personal injury law and the law as it relates to damages.