Lex Julia de adulteriis coercendis is a law (lex) passed by a member of the Julian family (Julia), in this case, Augustus, the first Roman Emperor, making adultery (adulteriis) or extra-marital sex of a noble or respectable woman immoral and illegal.
Prior to the passing of this law, these type of extra-marital relationships were dealt with by the family. Normally the father of the woman or husband would punish the immoral act in any way that they saw fit. The law, in essence, made adultery a crime that was punishable by the legal system that was regulated.
In most cases, men who were found to have committed adultery could not be charged with the crime. However, a man could be charged along with a woman who had been charged. In addition, a husband who did not bring charges against an adulterous wife or did not divorce her as a result of the adultery could be charged with pandering. Pandering could result in the same punishment as for adultery.
Punishment for adultery under the law normally constituted banishment. This resulted in each of the guilty parties being sent to different islands. The women would also lose her status in society and be prevented from remarrying another man.
The law was mainly presented as a means to curb immorality in society, especially where it affected respectable families by making public what was formerly considered to be a private matter. However, there does seem to have been a political agenda behind this, by accident, to stop the birth of illegitimate children and their potential claim to titles, property and other privileges.
There is further evidence to suggest that Augustus had a personal stake in enacting the law. His daughter, Julia, who he often spoke of in terms of her immorality, was forced into a strict upbringing in order to protect the public image of the house of Caesar.
In absentia, he denounced his daughter for reasons of having been found to have committed multiple acts of adultery. He disowned Julia and she was banished to Pandateria. With this, she lost all the status that she had gained through her birth and previous marriages to significant members of society. While there is some evidence of Julia’s proposed transgressions, none were publicly brought to light and no man was charged alongside her.
Julia, as well as his grand-daughters, are said to be the main reasons for Augustus’ obsession with morality in society and enacting laws to make adultery illegal. Whether Julia actually committed adultery or was simply in transgression of Augustus’ own moral standards and codes for a respectable woman is debatable.
Most cases were not tried in a court of law but rather by the Roman Senate. This is controversial as the legislation, punishment for the crime as well as other factors could be loosely interpreted rather than enforced by the judicial system in a regulated way.
While adultery is no longer illegal in many countries around the world, the act is still punishable by law, religious precepts as well as privately.