Substantive vs. Procedural Law

All law is either substantive or procedural. Substantive law is the law setting forth the rights and duties of individuals. For every right, there is a corresponding duty. Procedural law is the law setting forth the rules that must be followed when working within the legal system. The case law created by the courts can be either substantive or procedural law. Contract law, is a type of substantive law which defines what parties must do to create a contract and what their rights are if the party with whom they contracted fails to honor their obligations under the contract. The primary source of procedural law in the federal courts is court rules. Judges create and adopt their own rules for the conduct of cases in their courts. Each court similarly also has their own sets of rules called rules of civil procedure. Failure to comply with procedural law can result in a case being dismissed or some other consequence. Although paralegals must learn a certain amount of substantive law, they must master procedural law.
All substantive law is either public or private or criminal or civil. Public law consists of rules which involve the relationship of government to society as a whole. Constitutional law, administrative law, and criminal law are examples of public law. Private law consists of rules which involve the relationship of private individuals to each other. Most civil law is private law, including tort law, contract law, and most property law.
Criminal law consists of rules designed to protect society by providing minimum standards of conduct which must be observed by each of its members. Civil law consists of legal rules that focus on the rights and duties of individuals in relation to each other.