Government: The government of the ancient Mesopotamians was an unusual form of government. There was a king and nobles who made the law and declared war and decided how to honor the gods. Then there was an assembly of the people who could overrule the king and say, this is not a good law, get rid of it, or we don't want to go to war, so stop it. The kings, if they were wise, would listen to the people.
Sumerian Laws: The Sumerians did not, to our knowledge, write down their laws. The king passed a law, and everyone was expected to learn it and obey it. If you broke the law in Sumer, you would be punished. The punishment was set for each infraction. If you stole something, you were punished according to what you stole. If you offended the gods, you were punished. Everyone knew what the punishment was so there was no escape by saying you didn't know. The thing is, the Sumerians were organized into city-states. Each city-state had it own royal family and its own military and its own king and assembly of people. So a king in one city-state might pass a law, and pretty soon, if it was a good law and stuck around, all the city-states adopted the same law. So, although they were separate city-states and fought each other all the time, they also had pretty much the same laws and punishments, culture, urban life-style, language, and religion. People were free to move from city to city for trade and also to live.
Babylonian Laws: As the Sumerian city-states weakened, the city-state of Babylon took over. For a while, ancient Babylon ruled the whole Mesopotamian region in the south. The government and laws of Babylon were like the government and laws of Sumer. There was a king and other nobles who ruled with the help of an assembly of the people. The laws of Babylon were taken from the laws of Sumer. Everyone was expected to know and obey the laws. To ensure that the laws were followed by everyone, one of the kings of Babylon, King Hammurabi, had the laws written down on stone tablets so that everyone would be treated equally under the law. Most of these laws were taken from Sumerian law.
Assyrian Laws: Assyria was a powerful military state in northern Mesopotamia (in what is today northern Iraq). The Assyrian government was led by a king. The king ruled as the earthly representative of the god Ashur, the most powerful god to the ancient Assyrians. Military officers were in charge of local government. The king had other advisers as well, pulled from the nobles. The most important advisor was the chief of staff. The chief of staff decided who could talk to the king on any one day, and who couldn't. Scribes were the only people who could read or write. Like all the Mesopotamians, the Assrians liked to keep lists and write things down. At one time, the Assyrian Empire stretched all the way from Mesopotamia to Egypt. In ancient Assyria, there was no assembly that could overrule the king. The king's word was law.