Several Old Sumerian kings speak of Utu as their king, and this can be attested by the kings´ name forms, which may include the name of the god or his epithets in it. In the Sumerian tradition, Utu is the son of Nanna, the Moon Lord and his consort Ningal, and twin brother of Inanna, the Great Goddess of Love and War, showing therefore that the Light of the Day came from the Torch of the Night and the Lady of Dreams. Nanna and Ningal had another son, the patron god of weather changes and holder of thunderbolts, Ishkur or Adad, Utu´s younger brother. In Akkadian tradition, Utu/Shamash is sometimes the son of Anu, the Skyfather, or Enlil, the Air Lord. Utu´s consort is Sherida (Sumer) or Aya (Akkadian for dawn). The two principal temples of Utu were both called E-babbar, or White House, and were located in Sippar (in the North) and Larsa in Southern Sumer.Utu´s social role is therefore as guardian of justice, as judge of gods and men. In such position, he presides in the morning in cournts such as the one we know from the Bathhouse Ritual, where demons and other evildoers are sued by their human victims. At night, Utu/Shamash judges disputes among the dead of the Underworld. He is the last appeal of the wronged, who can obtain no justice from their fellow men, and their cry of despair to him, i-Utu, was feared as possessing supernatural power.
Basically, each morning Utu rises from the 'interior of heaven' with rays out of his shoulders in the East and crosses the firmament and all heavenly luminaries before finally reentering through the corresponding set of gates in the west. This means the Sun god travels to the Underworld everyday, becoming one of its Luminaries of the Land of No Return during nightime. Thus, Utu/Shamash is one of the Ever-Returning Deities of Mesopotamia, who travel to the Depths Below entering its Gates at Sunset and returning to brighten up the Heights Above at dawn every single day. The West Gates where the Sun sets in the Epic of Gilgamesh are said to be guarded by the Scorpion People, beings half human, half scorpion, the first Otherworld challengers Gilgamesh had to meet and win over in his search for immortality. Utu/Shamash travels the skies either on foot or in a chariot, pulled by fiery mules. His domain is called in The Phoenician Letters (by Wilfrid Davies and G. Zur, Mowat Publishing, Manchester, UK, 1979) the High Country, the heavenly sphere where the stars can be found.
In terms of character, Utu/Shamash is the Light that All Sees, and thus regarded as a god of truth, justice, and right. Thus his association to law and order, as well as a provider of clarity for oracles. He rules over the facts and acts which should guide righteous living, the standards for truthful action and deeds in the world, thus being the god for omens and oracles, because His is also the Will of the Ensouled Universe. Marduk, on the other hand, can be associated with the Law in the sense of being the Letter of the Law, the power that should be applied to Perfection to ensure the prosperity of the land. What the Spirit of the Law dictates (Utu/Shamsh) is accomplished by the coding of Harmonious Living, or the Power of Marduk. Utu/Shamash together with the storm-god Adad, he was often invoked in extispicy rituals.