Crime is an inexcusable offence that may take different forms. For example, sedition, treason and espionage are crimes against the state where as murder, rape, kidnapping and assault are crimes against a person. Under criminal law, the government always files the suit where as in case of civil law a private party always files the suit.

Criminal law explains criminal offences and its elements and the punishment for the convicted offenders as an effective means of social control. The most important feature of the U.S. criminal law is its provision for common punishment. Certain criminal laws prescribe rules and regulations to observe and maintain higher standards of conduct. For example, helping the police in investigation when asked to do so and reporting to authorities immediately after a culprit is identified are examples of moral or ethical criminal laws.

According to the U.S. constitution there are certain crimes called strict liability crimes like drug abuse and weapon offences where the act itself is sufficient to punish the offender. Here the criminal law imposes liability without fail. In the U.S. crimes like conspiracy, terrorism and sexual harassment are dealt under inchoate crime laws where anyone aiding in planning and execution of the crime is subjected to the same penalties as a person who actually commits the crime. The crime could be the result of a direct cause or a legal cause or an intervening cause. Therefore, criminal law gives immense importance to the concept of causation.

Everybody wants the criminal to be punished for the crime he has committed. Penalties should be of such nature that the criminal would not dare repeat the act he has committed.