In the earlier discussions of government, I've noted that it needs to determine the general principles or rules that determine what is an appropriate use of force. The goal is to determine an objective method of deciding whether an action is appropriate or not. This objective methodology is called the law. The law comprises the principles that determine what actions are appropriate or not, the methods used to determine this appropriateness, the appropriate punishments, and any other details necessary to provide an objective method of retaliatory force.
If the goal of the government is ultimately to protect individual rights, one important step is to explain clearly what exactly is a violation of rights, and what isn't. Communication of the principles of proper use of force would need to be stated clearly and ahead of time. The law satisfies this goal. It puts the standards of judgment into an objective format that people can understand and apply, avoiding any violations of the law.
The legislative branch of government is responsible for defining the law. This is one of the key functions of government. Making a decision with a huge number of people involved can be very difficult. Just try getting 10 people to agree to a restaurant for a meal.
So actually determining the law is a significant part of the job of the government. If everyone agreed ahead of time what was an appropriate action and what wasn't, there would still be plenty for the government to do. But when you have widespread disagreement on many issues, you start seeing some of the complexities associated with the epistemological need for government. Coming to a conclusion with so many people involved is incredibly difficult.
But remember that's the job that needs to be done. We have to solve the problem of being able to use retaliatory force in a way that doesn't itself appear to be an initiation of force to others. The government is instituted to find a reasonable solution to this problem. And the first step is to establish the standards by which actions are to be judged.
I've also written an article that briefly explores the idea of what form laws should take.