The two main branches of law are substantive and procedural law. Procedural law sets forth the steps and procedures involved in enforcing civil and criminal laws. Substantive law is the sector of the legal system that determines the obligations and rights of people and legal entities. This branch of the legal system refers to private law and public law and included contracts, real estate, torts and criminal justice.
Substantive laws derive from common law as well as legislative statutes. As more statutes are created and passed, the volume of substantive law increases and changes. In the 20th century, substantive laws were refined to replace many statutes based more upon conservative common law principles. For example, in the United States, new substantive laws have provided the Uniform Commercial Code governing commercial transactions. This code has been adopted in part or whole by all states as the authority of substantive law in the commercial sector and has made application of complex legal principles more uniform in order to facilitate more consistent laws of interstate commerce.
Some legal concepts seem to overlap both branches of law, which can cause confusion. Substantive law defines how a crime or tort will be charged and how the evidence and case facts will be presented and handled. Procedural law dictates how the processes leading up to trial and including the trial will occur. The criminal code that sets out the elements of a crime and what evidence is necessary to charge and support a verdict of guilt is substantive in nature, and the procedural laws that determine how the rights of the plaintiff and defendant will be protected and enforced throughout the course of the case are procedural. For example, the definition of manslaughter is substantive, and the right to a speedy trial for a person accused of manslaughter is procedural.
Many people consider procedural law more important than substantive law, but one would not be effective without the other. Substantive law concepts define what is right and wrong but also give the expectation that doing wrong will come with a penalty. Police and courts rely on procedural law to determine how evidence is obtained, searches are conducted, arrests are made, bail is set, defendants are treated, juries are chosen, presentation of evidence will occur at trial and sentencing will proceed. Without laws of a substantive nature, procedural law would not have much to regulate, and without those of a procedural nature, fair and consistent application of substantive law would be nearly impossible to maintain and enforce.
