Criminal Law 1.2: The Sources of Criminal Law
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Sources of Criminal Law

So this is a class in criminal law. However, there's a problem with that idea, which is that there is no one criminal law. There's no "the criminal law" for the whole country. Why is that? As I noted in the last lesson, criminal law is statutory. You can't have criminal law without some legislature writing down criminal law in a statute book.

And that means that the criminal law in Illinois is going to be very different than the criminal law right across the border in Missouri. So in fact, we have criminal law that looks different in each of the fifty states in the country. There's also federal criminal law that's passed by Congress at the federal level. There's criminal law in the district of Columbia, and then every city or municipality might have its own municipal criminal code as well. So how can we have a class in "the criminal law" if there is no "the criminal law"?

Well, what we're going to do is we're trying to teach you some principles and common approaches so that whatever jurisdiction you happen to be in, you can have the tools you need to understand what criminal law looks like. And we're going to do that by drawing on a couple of significant sources of criminal law rules.

Common Law Approach

The first we're going to call the common law approach. Now I said before that criminal law is not a common law area. It's not an area where judges are making the rules. Instead, criminal law is going to come from statutes, but that wasn't always true. For hundreds of years, criminal law was made by judges. And so when we talk about the common law approach, we made a continuous approach that started way back in England and that continues in many jurisdictions to this day where some of these criminal laws that were originally recognized by judges have been written down in statutes and judges have continued the traditions of the criminal law and applying those rules and using a certain interpretive approach to the statutes.

Model Penal Code

And then we're going to contrast that with a different source of law. This is something called the Model Penal Code. This is a model law drafted by the American Law Institute through its lead reporter, a law professor named Herbert Wechsler, in the 1950s. The American Law Institute is a private nonprofit organization that publishes documents that you might have heard of like the Restatement of Contracts or the Restatement of Torts. Restatements are documents that are designed to explain what the common approach is to a particular area of law across the country. The Model Penal Code was different. It was designed to try to influence the law. The hope was legislatures would read the model code and use it as, well, a model and amend their criminal statutes and move it away from some of the antiquated notions of the common law. That hasn't totally happened. Legislatures in some places have codified bits and pieces of it. And the Model Penal Code has been influential.

And sometimes we can look at a particular jurisdiction and say it has adopted this Model Penal Code rule for this area of law, but this other area of criminal law, they're still following the common law rules. And so we are going to try to teach you both of those sources of rules so you can understand what the rules are going to be in any one jurisdiction. But that's not all.

Constitutional Rules

There's one other important source of law we're going to look at and that is constitutional rules. This is not a class in constitutional law, however, there are a few areas where constitutional law imposes some important limits on criminal lawmaking. And those are particularly important for us to learn because when that is the case, no state, no jurisdiction can violate those constitutional rules. So you should take special note of any constitutional provisions that we're going to cover.

And the goal is if you learn these different sources of law, if you learn the general approach that courts took in the common law tradition, if you learn the alternate approach suggested by the Model Penal Code, and you understand the constitutional constraints that are imposed by the constitution, you will have the basic tools you need to practice criminal law in any jurisdiction. Although you will have to learn the specific rules that apply in that specific jurisdiction.


I. Statutory Criminal Law

  • Criminal law is statutory law, meaning that criminal laws are written down in a statutory book by a legislature.

  • Each state has its own criminal laws, as does the District of Columbia.

  • The federal government also has federal criminal laws.

  • Every city or municipality might also have its own municipal criminal code.

II. Sources of Criminal Law Rules

A. The Common Law

  • Judge-made criminal law was used back in England. Future court decisions had to be made in line with legal precedents from previous court decisions.

  • Today, much of this old judge-made law has been codified in statutes. And judges have continued the Common Law traditions in criminal law, applying those rules and using a certain interpretative approach to the statutes.

B. The Model Penal Code (MPC)

  • The MPC is a model law drafted by the American Law Institute in the 1950s.

  • The MPC was designed to influence legislatures, who could look to the MPC as a model for their own criminal statutes, in an attempt to move statutes away from some of the Common Law’s antiquated notions.

  • Some jurisdictions have followed the MPC model for some of their criminal statutes. In some jurisdictions, the criminal code may follow the MPC model in certain areas of the law but follow the Common Law in other areas of the law.

C. The Constitution

  • The Constitution places some limits on criminal lawmaking. No jurisdiction can violate constitutional rules.

III. Conclusion

  • Understanding these sources of criminal law rules provides the basic tools for understanding criminal law in any jurisdiction, although you will have to learn the specific rules that apply in the particular jurisdiction.

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