Jonas's society is filled with rules about anything and everything. They even have rules about when a child has to give up his or her comfort object. The text isn't exceptionally clear about who established the rules. The Giver tells Jonas that many of the rules were established long before his time. He doesn't say who the original rule makers were.

The society is governed by the Elders, and they presumably make new rules, modify existing rules, and even get rid of certain rules. I would like to point out that chapter two does have a reference that some rules might be changed by a committee, and the committee isn't necessarily made up of Elders. Changing a rule isn't easy, and it apparently takes committees a long time to come to any consensus about a change:

There was talk about changing the rule and giving the bicycles at an earlier age. A committee was studying the idea. When something went to a committee for study, the people always joked about it. They said that the committee members would become Elders by the time the rule change was made.

That quote seems to suggest that the Elders have given committees composed of non-Elders the power and ability to establish or modify certain rules.

Jonas's society is controlled by the Committee of Elders, which is an oligarchic group that makes every significant decision throughout the community. The enigmatic Committee creates the rules and regulations that the citizens are required to follow in order to avoid being "released." The Committee of Elders sanctions marriages, plans individual families, controls the birth rate, organizes community functions, regulates the number of community members, and decides each citizen's occupation. The Chief Elder is the Committee of Elders' representative, who hosts the annual ceremonies and speaks on behalf of the ruling group. With the help of the Speaker, the Committee of Elders successfully creates a stable society that is driven on the principles of Sameness. Overall, the Committee of Elders is the oligarchic ruling group that creates laws and regulations in Jonas's austere society.

The rulers do. They are the elders in the community and function as sort of a government council. There is a chief Elder who is elected every 11 years.