The Titaness known for divine law who sided with Zeus during the Titanomachy was Themis.
Themis was one of the twelve Titans, the daughter of Gaia and Uranus. Her name refers to divine law, established custom, and the proper order of society rather than merely human legislation. She was associated with justice, assemblies, prophecy, and the rules that maintained harmony among gods and mortals.
Most summaries of the Titanomachy identify Themis as an ally of Zeus rather than a supporter of her brother Cronus. Prometheus, her fellow Titan ally in many accounts, also joined the Olympian side. Their choice helped distinguish the war from a simple conflict between every older god and every younger one.
After Zeus’s victory, Themis retained an honored position among the Olympians and became Zeus’s second wife in the standard genealogy. Together they were said to have had the Horae, including Eunomia, Dike, and Eirene, and in some traditions the Moirai. She was also linked with ancient oracles, especially Delphi, before Apollo’s association with that sanctuary.