The final play of the Oresteia, called The Eumenides (Εὐμενίδες, Eumenídes), illustrates how the sequence of events in the trilogy end up in the development of social order or a proper judicial system in Athenian society. In this play, Orestes is hunted down and tormented by the Furies, a trio of goddesses known to be the instruments of justice, who are also euphemistically referred to as the "Gracious Ones" (Eumenides). They relentlessly pursue Orestes for the killing of his mother. However, through the intervention of Apollo, Orestes is able to escape them for a brief moment while they are asleep and head to Athens under the protection of Hermes. Seeing the Furies asleep, Clytemnestra's ghost comes to wake them up to obtain justice on her son Orestes for killing her.
After waking up, the Furies hunt down Orestes again and when they find him, Orestes pleads to the goddess Athena for help and she responds by setting up a trial for him in Athens on the Areopagus. This trial is made up of a group of twelve Athenian citizens and is supervised by none other than Athena herself. Here Orestes is used as a trial dummy by Athena to set-up the first courtroom trial. He is also the object of central focus between the Furies, Apollo, and Athena. After the trial comes to an end, the votes are tied. Athena casts the deciding vote and determines that Orestes will not be killed. This ultimately does not sit well with the Furies, but Athena eventually persuades them to accept the decision and, instead of violently retaliating against wrongdoers, become a constructive force of vigilance in Athens. She then changes their names from the Furies to "the Eumenides" which means "the Kindly Ones". Athena then ultimately rules that all trials must henceforth be settled in court rather than being carried out personally.