This paper provides a broad introduction to criminal law in the United States, examining how crimes are defined at the local, state, and federal levels. It outlines the primary functions of criminal law, including due process guarantees, victim protection, prosecution, and sentencing. The paper also discusses justification and excuse defenses, the roles of prosecutors and defense counsel, and the constitutional safeguards — particularly those found in the Bill of Rights — that protect individuals from wrongful prosecution. Drawing on the Model Penal Code and foundational legal principles extending from the Magna Carta, the paper situates criminal law as both a practical framework and a cornerstone of democratic governance.
Criminal law is defined at both the state and federal levels of American government. In the United States, "most crimes are established by local, state, and federal governments," with the exception of common law crimes ("Criminal Law," 2010). While some definitions of crimes vary significantly from state to state, for the most part states conform to the Model Penal Code. Criminal law is the aspect of government that focuses on the prosecution of acts defined as crimes at the local, state, or federal level.
Criminal law therefore invokes constitutional clauses such as the due process of law. Individual citizens have the right to legal representation and are theoretically equally protected under the law. Criminal law thus serves several distinct and sometimes conflicting interests: the prosecutor (usually the local, state, or federal government); the victim of the crime; and the defendant or accused.
When a crime is committed, any suspects are subject to criminal legal procedures of the state. Due process always applies, and criminal law operates within the realm of constitutionally guaranteed rights and freedoms. The state bears the burden of proof to determine whether an individual is guilty of a crime. At the same time, the state has at its disposal a wealth of resources that can help victims achieve justice for criminal wrongdoing.
The main functions of criminal law include the following. First, any person deemed a criminal offender is guaranteed due process, a right established in the United States Constitution and extending from the Magna Carta. Second, when a crime is committed, the victim is guaranteed protection by the state. When a crime is victimless, the state acts on behalf of public welfare, health, or safety. For example, drug crimes are generally considered victimless offenses. White-collar crimes may be classified as criminal yet have no specific identifiable victim, as in cases of fraud.
Further functions of criminal law include the ability of the state to prosecute or pass judgment on an offender. This process involves access to due process of law, which may or may not involve a trial. In many cases, criminal matters are resolved outside of a courtroom through legal proceedings that do not depend on a public jury. The state prosecutor and the accused each have access to legal services, and a series of negotiations determines any sentencing. In such negotiations, a formal declaration of guilt or innocence may not be entered.
When a criminal case is brought to trial, a jury of peers determines the guilt or innocence of the defendant based on evidence presented in court. Criminal law is therefore an integral part of the democratic process. Ideally, citizens are engaged enough in the judicial process to evaluate evidence in an unbiased manner and to determine the best course of action based on the laws of the state. A judge — who may or may not be elected by voters — typically determines the sentence. Different crimes warrant different sentences.
The distinction between cases resolved through plea negotiations and those decided at trial is significant. In plea negotiations, the defendant may agree to plead guilty to a lesser charge in exchange for a reduced sentence, bypassing the need for a full trial. This practice is a central feature of the American criminal justice system and shapes the outcomes of the vast majority of criminal cases. For a broader overview of how these procedures work, see criminal procedure in the United States.
Depending on the jurisdiction, criminal justice sentencing may exist for punitive (punishment) purposes, for preventative purposes, or for public safety purposes. In some cases, sentencing is also intended to serve rehabilitative purposes. The philosophy underlying criminal law is important, but the practical applications of criminal law are equally — if not more — consequential in determining outcomes for defendants, victims, and communities.
"Punitive, preventative, and rehabilitative sentencing goals"
"Justification and excuse defenses under criminal law"
"Bill of Rights guarantees against wrongful prosecution"
You’re 58% through this paper. Sign up to read the remaining 3 sections.
Sign Up Now — Instant Access Already a member? Log inAlways verify citation format against your institution’s current style guide requirements.