In the United States’ legal system, there are four main sources of law. These are constitutions, statutes, administrative regulations, and case law.
- Constitutions are the laws that establish systems of government (state or federal). They set out the limits of what governments can and cannot do. Within any state, the constitution overrides any law that contradicts it. The US Constitution is the supreme law of the land and no law (including a state constitution) can violate it.
- Statutes are what we often think of as law. These are the laws passed by legislative bodies. Congress passes statutes that apply to the country as a whole, state legislatures pass state laws, and local legislatures (often called city councils) pass laws that apply only to their own localities.
- Administrative regulations are rules that are written by agencies of the executive branch. These government agencies have the authority to write rules because the legislatures give it to them. These agencies’ employees are supposed to be experts who will be better at writing detailed rules than the legislators are. Any administrative regulation can be overridden and repealed by the legislature.
- Case law consists of decisions and opinions issued by courts in various legal cases. Courts are asked to interpret the laws. When they do so, their opinions as to what the laws mean help to shape the law. For example, the recent Supreme Court ruling on gay marriage shaped the law to say that the Constitution recognizes a right to such marriages.