The law dealing with rights, duties and liabilities, as contrasted with procedural law, which governs the technical aspects of enforcing civil or criminal laws
That law which establishes rights and obligations, as distinguished from procedural law, which is concerned with rules for establishing their judicial enforcement An easier way of looking at this is that "substantive law" is what you sue someone for or over, and procedural law is the "nuts and bolts" of how you would bring that suit