Substantive law is statutory law passed by a legislature that dictates how people should behave. Procedural law ensures adherence to due process and governs how a legal case flows. These two types of law work closely together in civil and criminal cases.
By definition, substantive laws deal with the areas of the law that establish obligations and rights of individuals, and dictate what people may or may not do. Each law has independent power to decide the fate of individual cases, but it cannot be applied in non-legal contexts. This type of law is passed by a government.
On the other hand, procedural law, by definition, determines how substantive law may be enforced, and according to Duhaime, seeks to ensure the fairness and transparency of such enforcement. This type of law comes with no independent powers and can be applied to non-legal contexts. Procedural law can be regulated by statutory law.
An example of procedural law in practice may be something like a person having the right to be made aware of all charges against him or her within 72 hours of being arrested. Substantive law in the real world would be gathering facts and evidence to substantiate the charges brought against someone. In other words, certain things must be proven before someone can be taken into custody and charged with a crime.