Substantive law is distinct from remedial or procedural law. Its primary function is to create, define, and regulate rights and duties. Substantive law provides the essential foundation for the legal system, as procedural law cannot exist without it.

An example is Article 1170 of the Civil Code, which is substantive law that makes obligors liable for damages resulting from fraud, negligence, delay, or contravention of their obligations. These defined rights and duties form the basis upon which legal actions and procedures are based.