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Criminal law (also known as penal law) is the body of statutory and common law that deals with crime and the legal punishment of criminal offenses. There are four theories of criminal justice: punishment, deterrence, incapacitation, and rehabilitation. It is believed that imposing sanctions for the crime, society can achieve justice and a peaceable social order. This differs from civil law in that civil actions are disputes between two parties that are not of significant public concern.
The process begins, obviously, with an alleged crime. A complainant makes an accusation, which is investigated by the police, acting as agents of the government. The police file a document, in most jurisdictions known as a complaint, with a court in the appropriate jurisdiction. If the alleged offense is classified as a felony, the Constitution of the United States requires that the case be referred to a grand jury for an indictment. An indictment is the official charging instrument accusing the defendant of criminal conduct.
The interests of the state are represented by a prosecuting attorney, while the interests of the defendant are represented by his or her defense attorney. While the specific process varies according to the local law, in virtually every jurisdiction the process culminates with a trial, followed by appeals to higher courts.
Criminal statutes spell out the exact circumstances which constitute a crime. These circumstances are known as the elements of the offense. Unless all the elements are proven by the prosecuting authority, the defendant is not guilty of the offense. There are three kinds of elements: the act itself, the actus reus, guilty act; the requisite mental state, the mens rea, guilty mind; and the attendant circumstances. As an example, the common law definition of burglary was as follows: unlawful entry into a dwelling house at night with the intent to commit a felony therein. It is the duty of the prosecution, therefore, to prove not merely the act (the entry), and the mental state (the intent to commit a crime), but all the attendant circumstances (that it was a dwelling house, and that it was at night). Most modern criminal statutes have, among other changes, eliminated the "at night" element.
In defense, the accused could argue that he had no intent to commit a crime inside the house, that it occurred during the day, or that his entry was lawful. He could also, of course, argue that the incident never happened, or that someone else committed the offense.
Criminal law in most jurisdictions, both in the common and civil law traditions, is divided into two fields:
Criminal procedure regulates the process for addressing violations of criminal law
Substantive criminal law details the definition of, and punishments for, various crimes.
Criminal law distinguishes crimes from civil wrongs such as tort or breach of contract. Criminal law has been seen as a system of regulating the behavior of individuals and groups in relation to societal norms at large whereas civil law is aimed primarily at the relationship between private individuals and their rights and obligations under the law. Although many ancient legal systems did not clearly define a distinction between criminal and civil law, in England there was little difference until the codification of criminal law occurred in the late nineteenth century. In most U.S. law schools, the basic course in criminal law is based upon the English common criminal law of 1750 (with some minor American modifications like the clarification of mens rea in the Model Penal Code)
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Unlike criminal law, civil law regulates relationships amongst persons and organizations. Civil law, in this sense, is usually referring to redress to civil law courts (as opposed to criminal courts) and is often used as a means to resolve disputes involving accidents (torts such as negligence), libel and other intentional torts, contract disputes, the probate of wills, and trusts, and any other private matters that can be resolved between private parties. Violations of civil law are considered to be torts or breaches of contract, rather than crimes. Depending upon the regional government, this field of law contains commercial law and some kinds of administrative law remedies, though sometimes administrative law judges adjudicate penal law violations such as parking tickets and other minor offenses.
Contractual law enforces contracts by allowing a party(the plaintiff), whose rights have been violated or breached