Government includes the people and resources—as well as departments, agencies, programs, processes, laws, rules, and regulations—that define the relationship between federal, state, and local governments and their citizens. Some legal principles have a unique application when private citizens or entities interact with their governments.

In Illinois, as in other states, the government is composed of three levels: federal, state, and local. Each level has its own departments, agencies, programs, processes, laws, rules, and regulations that govern the interactions between the government and its citizens. The federal government operates under the U.S. Constitution and federal law, while the state government of Illinois operates under the Illinois Constitution and state statutes. Local governments, such as counties and municipalities, have their own ordinances and regulations. Legal principles that apply to interactions between private citizens or entities and the government include administrative law, which governs the actions of state and federal agencies, and constitutional law, which protects citizens' rights. Illinois has its own body of administrative law and procedures that guide how state agencies create and enforce regulations, as well as how citizens can challenge agency decisions. Additionally, the Illinois Constitution provides for a range of individual rights and outlines the structure of the state government. When private citizens or entities in Illinois interact with the government, they must navigate a complex web of laws and regulations that are specific to the level of government they are dealing with.