In the American legal system, all of the substantive rules of law emanate from one of the following sources: Constitutions Legislative Enactments (Statutes) Case Law The term substantive law refers to those laws which define the rights and duties of individuals towards one another and towards the state. Federal and State administrative agencies are also authorized to promulgate rules and regulations. For Federal Agencies these rules are found in the Code of Federal Regulations. Procedural law, which makes up the ground rules for the way cases proceed through the court system, is often found in rules laid down by the courts themselves. California's rules are found in the California Rules of Court. For the Federal Judicial System these rules are found in the Federal Rules of Civil Procedure and the Federal Rules of Criminal Procedure. The Federal Rules of Evidence are a hybrid of substantive and procedural law. Back to top of page.