28  Section 3.1: Sources of Criminal Law

The primary function of the substantive criminal law is to define crimes, including the associated punishment. The procedural criminal law sets the procedures for arrests, searches and seizures, and interrogations. In addition, it establishes the rules for conducting trials. Where does criminal law come from?

  The Common Law

The term common law can be disturbingly vague for the student. That is because different sources use it in several different ways with subtle differences in meaning. The best way to get a grasp on the term’s meaning is to understand a little of the history of the American legal system. Common law, which some sources refer to as “judge-made” law, first appeared when judges decided cases based on the legal customs of medieval England at the time. It may be hard for us to imagine today, but in the early days of English common law, the law was a matter of oral tradition. That is, the definitions of crimes and associated punishments were not written down in a way that gave them binding authority.

By the end of the medieval period, some of these cases were recorded in written form. Over a period, imported judicial decisions became recorded on a regular basis and collected into books called reporters. The English-speaking world is forever indebted to Sir William Blackstone, an English legal scholar, for collecting much of the common law tradition of England and committing it to paper in an organized way. His four-volume set, Commentaries on the Laws of England, was taken to the colonies by the founding fathers. The founding fathers incorporated the common law of England into the laws of the Colonies, and ultimately into the laws of the United States.

In modern America, most crimes are defined by statute. These statutory definitions use ideas and terms that come from the common law tradition. When judges take on the task of interpreting a statute, they still use common law principles for guidance. The definitions of many crimes, such as murder and arson, have not deviated much from their common law origin. Other crimes, such as rape, have seen sweeping changes.

One of the primary characteristics of the common law tradition is the importance of precedent. Known by the legal Latin phrase stare decisis, the doctrine of precedence means that once a court makes a decision on a particular matter, they are bound to rule the same way in future cases that have the same legal issue. This is important because a consistent ruling in identical factual situations means that everyone gets the same treatment by the courts. In other words, the doctrine of stare decisis ensures equal treatment under the law.


When the founding fathers signed the Constitution, they all agreed that it would be the supreme law of the land; the Framers stated this profoundly important agreement in Article VI. After the landmark case of Marbury v. Madison (1803), the Supreme Court has had the power to strike down any law or any government action that violates constitutional principles. This precedent means that any law made by the Congress of the United States or the legislative assembly of any state that does not meet constitutional standards is subject to nullification by the Supreme Court of the United States.

Every state adopted this idea of constitutional supremacy when creating their constitutions. All state laws are subject to review by the high courts of those states. If a state law or government practice (e.g., police, courts, or corrections) violates the constitutional law of that state, then it will be struck down by that state’s high court. Local laws are subject to similar scrutiny.

  Statutory Law

Statutes are written laws passed by legislative assemblies. Modern criminal laws tend to be a matter of statutory law. In other words, most states and the federal government have moved away from the common-law definitions of crimes and established their own versions through the legislative process. Thus, most of the criminal law today is made by state legislatures, with the federal criminal law being made by Congress. Legislative assemblies tend to consider legislation as it is presented, not in subject order. This chronological ordering makes finding the law concerning a particular matter very difficult. To simplify finding the law, most all statutes are organized by subject in a set of books called a code. The body of statutes that comprises the criminal law is often referred to as the criminal code, or less commonly as the penal code.

  Administrative Law

The clear distinction between the executive, legislative, and judicial branches of government becomes blurry when U.S. governmental agencies and commissions are considered. These types of bureaucratic organizations can be referred to as semi-legislative and semi-judicial in character. These organizations have the power to make rules that have the force of law, the power to investigation violations of those laws, and the power to impose sanctions on those deemed to be in violation. Examples of such agencies are the Federal Trade Commission (FTC), the Internal Revenue Service (IRS), and the Environmental Protection Agency (EPA). When these agencies make rules that have the force of law, the rules are collectively referred to as administrative law.

  Court Cases

When the appellate courts decide a legal issue, the doctrine of precedence means that future cases must follow that decision. This means that the holding in an appellate court case has the force of law. Such laws are often referred to as case law. The entire criminal justice community depends on the appellate courts, especially the Supreme Court, to evaluate and clarify both statutory laws and government practices against the requirements of the Constitution. These legal rules are all set down in court cases.

Key Terms

Administrative Law, Case Law, Commentaries on the Laws of England, Common Law, Criminal Law, Cybercrime, Damages, Embezzlement, Felony, Hate Crime, Misdemeanor, Ordinary Crime, Organized Crime, Phishing, Precedent, Procedural Criminal Law, Reporter, Sir William Blackstone, Stare Decisis , Street Crime, Substantive Criminal Law, Tort, Visible Crime 


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