At the federal level, statutory laws originate in Congress. When a proposed law is written by a member of Congress, it is called a bill. CSU Stanislaus explains that when a bill becomes law, it turns into a public law. After that, the law is codified in the U.S. Code. On the state level, legislatures create regulatory laws that are eventually codified in state codes.
Regulatory laws from federal departments start as proposed rules in the "Federal Register" before codification in the "Code of Federal Regulations." Regulatory laws further interpret statutory laws by listing standards and procedures to follow, according to the National League of Cities.
Case law emanates from state and federal courts. On the federal level, district courts handle the initial jurisdiction before an appeal goes to circuit courts, according to CSU Stanislaus. The Supreme Court has the final say on case law in the United States.
LawHelp.org explains that different types of federal laws include immigration, bankruptcy, copyright and criminal laws. Each state passes its own laws as long as they do not conflict with federal laws.