The Capitol Pylon programme identifies Wisdom, Justice, Power and Mercy as the constant guardians of the law. It places Wisdom and Justice to the east, and Power and Mercy to the west.

Alexander’s History of Law · “The Majesty of the Law”
Wisdom, Justice, Power and Mercy: Constant Guardians of the Law
An archival programme sheet for the Capitol Pylon identifies the four constant guardians of the law.
Nebraska State Capitol
A Harmony of the Arts
Completing the Greek series is Orestes before the Areopagites. In the ancient play, The Oresteia, by Aeschylus, we see an example of violence begetting more violence in the House of Atreus. Orestes was on trial for killing his mother, Clytemnestra, because she had killed his father, Agamemnon. Back then, punishment for murder was left up to the victim’s family.
Orestes was being tried by the Council of Areopagus, which was the council composed of the city elders of Athens. The Areopagus was split evenly until Athena decided Orestes should be free. Athena then created the Areopagites, which created a court to provide wisdom and leadership and to forever end the concept of blood feuds in justice.
What is symbolic about this is that blood revenge was replaced by enlightenment and the rule of law. In the panel, Athena is depicted wearing a helmet and holding a spear and carrying a shield emblazoned with an owl, symbolic of wisdom for the power of the mind. If not for the ideas brought forth in The Oresteia, we might never have developed jury trials.
Source: Lee Lawrie's Prairie Deco: History in Stone at the Nebraska State Capitol, 4th Edition.
A Harmony of the Arts, Whitaker, AIA, 1926. The upper panel depicts the Trial of Orestes, and the lower panel depicts the Magna Carta.
A detail of Athena in the Trial of Orestes, with the Athenian owl.
The Golden Calf appears nearby. Mosaic Law and kingly law form early foundations of law in Western civilization. A Harmony of the Arts, Whitaker, AIA, 1926.