In the first part of this myth, we see Orestes continuing the cycle of violence that's been plaguing his family. If the cycle were to continue, then someone would have to kill Orestes for killing Clytemnestra and Aegisthus, then someone else would have kill whoever killed Orestes, and someone else would... oh, you get the point.
Fortunately for Orestes, Apollo steps in and gets Athena to whip up a court for Orestes to be tried in. When Orestes is found innocent, we see the first example of a person being absolved of a crime due to extenuating circumstances. More importantly than that, though, we see the triumph of law over the bloody, vengeful practices of the past.
Questions About Justice and Judgment
Why would Athena make a good judge?
Do you think Orestes deserves to be freed? Why, or why not?
How do you think Agamemnon would judge the actions of his son?
What is the difference between getting justice and getting revenge?