Ever since Cain slew Abel (if not since Adam and Eve ate the apple), societies have had to deal with those whose acts seem “wrong.” A conclusion that an act is wrong may be simply innate. Some wrongs, however, seem worse than others. Thus, breaking a promise or tripping someone seems wrong, but homicide, rape, maiming, and so on seem “really” wrong. If a general consensus arises that specific acts are really wrong, there will be laws against such acts. Some acts will be criminally punished, while others will be handled by civil parts of the legal system. This book focuses on how that behavior is defined and punished as “criminal.”
American criminal law has three main sources: (1) the common law, (2) statutory law, and (3) constitutional law. Of these, the most important is statutory law, since it is now accepted that it is unconstitutional to punish someone unless his conduct was previously proscribed by the legislature. Nevertheless, criminal statutes are interpreted in light of an 800-year history of common law principles and against more modern constraints imposed by constitutional doctrines. The criminal law is yet further limited: Since most of criminal law consists of statutes, courts have established maxims of statutory interpretation, some rooted in the Constitution, others not. Of these, the most important are examined on pages 10 and 11, including the void-for-vagueness doctrine and the rule of lenity.
Finally, this chapter explores, if only briefly, the procedural limitation that requires the prosecution to persuade a jury beyond a reasonable doubt that the defendant is guilty. Just as important as the standard and its articulation are the reasons why the Supreme Court has held this standard to be required by the Constitution.
Early English custom condemned as felonies seven offenses: mayhem, homicide, rape, larceny, burglary, arson, and robbery. All other offenses were misdemeanors. These classifications became known as the “common law” because they were commonly shared.
The term “common law” is usually employed to refer solely to judge-made law, typically in the areas of torts and contracts. However, legislatures early became interested in defining crimes; therefore, in the context of criminal law, the term “common law” incorporates both statutes and judge-made law as well as judicial interpretations of statutes. The power of courts to “create” crimes existed until well into the nineteenth century and in some rare instances continues even today.