Government: In both Sumer and Babylon, there was an unusual form of government that came pretty close to an early form of democracy. There was a king and nobles who made the laws and declared war and decided how to honor the gods. Then there was an assembly of wise men, elected by the people, who could overrule the king and say, this is not a good law, get rid of it; or the assembly might say we don't want to go to war, so stop it. Each city-state had its own king and its own assembly. Government was quite different, however, in ancient Assyria.
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, whether they were rich or poor, everyone would be treated equally under the law. Most of these laws were taken from Sumerian law.
The Assembly in ancient Sumer and Babylon: In both ancient Sumer and ancient Babylon, kings were not gods. Kings were mortals, just like the common man. In this, at least, all men were equal in these ancient civilizations. The kings were just as eager and just as responsible for keeping the gods happy as were the common people. So, it made sense to these early people that a Council of Elders, an assembly of wise men (called the Assembly), should be elected so that the people would have someone to check with, to make sure that what they were planning to do would not anger the gods. The king sought approval for his actions from this assembly, just like everyone else. The assembly might say to a king, 'No king, you can't do that. That would anger the gods." And the king would not do that. Even the gods had to seek the approval of the assembly. The gods didn't actually appear in front of the assembly (and wouldn't that be a neat trick!) but the assembly did discuss how the gods should behave and arrange themselves in the heavens - which god could marry whom and who had what job.
Assyrian Laws: Things were quite different in ancient Assyria. 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 ancient Mesopotamians, the Assyrians liked to keep lists and write things down. At one time, the Assyrian Empire stretched all the way from Mesopotamia to Egypt. But in ancient Assyria, there was no assembly that could overrule the king. The king's word was law.