substantive law

Substantive law defines and regulates legal rights and duties. It encompasses the body of law that dictates how individuals and entities should behave and what rights they possess. For example, substantive law would describe how two parties enter into a contract. In contrast, procedural law outlines the methods for enforcing those rights and duties through the court system, including rules on jurisdiction, pleading, evidence, and appeals.1

Substantive criminal law specifically defines offenses and the principles for judging them, such as self-defense or insanity. A key principle is legality, meaning there can be no crime without a law, and laws must be clear, interpreted strictly, and not applied retroactively.2