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.
Constitutions
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