Crimes are usually classified as treason, felony, or misdemeanor. The fundamental distinction between felonies and misdemeanors rests with the penalty and the power of imprisonment. In general, a misdemeanor is an offense for which a punishment other than death or imprisonment in the state prison is prescribed by law. The term "degree of crime" refers to distinctions in the culpability of an offense because of the circumstances surrounding its commission. Crimes are sometimes divided according to their nature into crimes mala in se and crimes mala prohibita; the former class comprises those acts that are thought to be immoral or wrong in themselves, or naturally evil, such as murder, rape, arson, burglary, larceny, and the like; the latter class embraces those acts that are not naturally evil but are prohibited by statute because they infringe on the rights of others (e.g., acts in restraint of trade that have been made criminal under antitrust legislation).
In the United States, the power to define crimes and set punishment for them rests with the legislatures of the United States, the several states, and the territories, the principal authority being that of the individual states. This power in the states is restricted by the federal Constitution, e.g., in the Fourteenth Amendment and in prohibitions against acts of attainder (an act of attainder is a legislative declaration that a particular individual is guilty of a crime) and against ex post facto laws (laws that retroactively declare certain actions to be criminal). State constitutions may also limit state legislative action. The courts cannot look further into the propriety of a penal statute than to ascertain whether the legislature has the power to enact it. Administrative rules may have the force of law, and violations of such rules are punishable as public offenses, provided that the legislature has made such violations misdemeanors.
A common-law crime is one punishable under common law, as distinguished from crimes specified by statute. In many U.S. jurisdictions, including some in which comprehensive criminal statutes have been enacted, the common law in relation to crimes and criminal procedure has been recognized by the courts as in force, except insofar as it has been abrogated or repealed, expressly or impliedly, by statute. Thus the state may prosecute crimes that were indictable at common law even though they may not be denominated as such or be provided for by statute. In many other jurisdictions the courts have held the common law as to crimes as being abolished, and no act is punishable as a crime unless it is made so by statute, or unless the act is made punishable as a crime by the constitution. Criminal procedure is entirely regulated by statute. There are no common-law offenses against the United States, and one may be subject to punishment for crime in a federal court only for the commission or omission of an act defined by statute or regulation having legislative authority, and then only if punishment is authorized by Congress. In general, crimes must be defined in a penal statute with appropriate certainty and definiteness; the constitutional requirement of due process of law is violated by a criminal statute that fails to give a person of ordinary intelligence fair notice that the contemplated conduct is forbidden by the statute.
Except as otherwise provided by statute, to constitute a crime an overt act (actus reus) must be accompanied by a criminal intent (mens rea) or by such negligence as is regarded by law as equivalent to a criminal intent. Motive, or that which leads or tempts the mind to indulge in a criminal act, as distinguished from intent, is neither a crime nor an essential element of a crime. The motive with which an offense was committed is immaterial. Proof of motive may be material in proving that the defendant committed a particular crime, but it is not essential to a conviction.
Every accused has the right to any and all defenses the law recognizes and permits—e.g., insanity, mistake of fact, or self-defense. An accused having the right to resort to several defenses may make an election as to the one on which he or she will rely. The fact that one undertakes a crime on the advice, or as the agent, of another is not a defense; on the other hand, except in the case of homicide, an act that would otherwise constitute a crime may be excused when committed under duress or compulsion that is present, imminent, and impending, and that produces a well-grounded apprehension of death or serious bodily harm if the act is not done (see coercion). Religious belief is not ordinarily a justification or excuse for the commission of a crime (see bigamy).
The procedure in criminal cases is substantially the same throughout the United States. The person suspected of crime is taken into custody by a police officer, sometimes by service of a warrant of arrest. If the crime is serious, the case is first presented to a grand jury, which draws up an indictment if there is sufficient evidence to justify trial; otherwise it discharges the accused. While action is pending, the party charged may be released on bail. Trial is by jury or before a judge alone if a jury is not required, or if the defendant consents. The government presents its case (i.e., attempts to prove the allegations of the indictment), through the public prosecutor, usually called the district attorney, while the accused is represented by counsel that he or she has chosen or that the court has appointed. The legal presumption of innocence puts the burden of proving guilt beyond a reasonable doubt on the prosecution, unless, of course, the defendant pleads guilty to the charge. Special rules restricting the introduction of evidence in criminal trials further protect the defendant. If the accused is found or adjudged innocent, he or she is discharged; if the accused is found guilty, the judge pronounces sentence. (For types of criminal penalties, see capital punishment; corporal punishment; prison.) If the defendant is convicted, an appeal may be filed; the prosecution, however, cannot appeal an acquittal. Generally speaking, this procedure is confined to felonies; misdemeanors, being relatively less serious offenses, are handled in a more summary fashion. It is generally accepted that no court will enforce the criminal law of another jurisdiction, but by means of extradition a fugitive from justice may be delivered to the competent authorities.
See G. Williams, Criminal Law (2d ed. 1961); W. J. Chambliss, ed., Crime and the Legal Process (1969); S. H. Kadish, Criminal Law and Its Processes (1969).
Criminal Law is a film directed by Martin Campbell released in 1989. It is notable for having been an inspiration for Canadian serial killers Paul Bernardo & Karla Homolka, who changed their last names to "Teale", in honor of the film's villain, serial killer Martin Thiel, played by Kevin Bacon. Despite the fact that Karla requested a divorce from Paul in early 1993, she never bothered to revert back to her maiden name, she instead chose to keep Teale as her last name.