Final answer:
Hammurabi, the ruler of the Babylonian Empire, established the Code of Hammurabi, an extensive and enduring set of laws applicable to all his subjects.
Step-by-step explanation:
The ruler who established a code of law that had application for everyone in the Babylonian Empire was Hammurabi. Hammurabi ruled from approximately 1792-1750 BCE and is famous for creating the Code of Hammurabi, which is one of the earliest and most complete written legal codes known to history. It covered various aspects of daily life, and its inscriptions on stone pillars were erected throughout the empire to inform citizens about the laws and proper behavior. This set of laws included 300 edicts covering everything from inheritance and trade to sentencing for crimes, reflecting a deep concern for justice and fairness within the society.