The Main Parts of the Criminal Justice System

There are three main components of the American criminal justice system, each linked to one of the United States’ three branches of government. 

The legislative branch creates the laws which must be followed by members of the criminal justice system, ranging from law enforcement officers to lawyers and judges to jailers and prison personnel. The legislative branch also creates the laws which must be followed by all citizens, thereby creating the beginning of the criminal justice system. When one of a legislature’s laws is broken, a person may be arrested and charged with a crime. Legislatures exist at the local, state, and federal levels, with laws from different legislatures applying in different locations. A city council’s regulations apply within city limits, a state legislature’s laws apply within that state, and the U.S. Congress, the nation’s federal legislature, creates laws that apply throughout the 50 states or to actions that occur across state borders.

Due to the effects of the U.S. Constitution, all states must have similar laws.

The executive branch enforces the law and apprehends those who break it. Law enforcement is part of America’s executive branch, and various law enforcement organizations exist at the local, state, and federal levels. These organizations cannot arbitrarily create their own laws and must obey the laws set forth by their respective legislatures. Local law enforcement is often conducted by city police officers, county deputy sheriffs (sheriff’s deputies), or local constables or marshals. Local law enforcement officers must be certified as peace officers by their respective states, and local law enforcement organizations do not have jurisdiction outside their city or county borders.

State-level law enforcement is conducted by state police, highway patrol, and investigative bureaus. Personnel from these organizations have statewide jurisdiction. State police and highway patrol may perform local law enforcement duties for small villages and towns who do not have their own police forces, assisting county sheriffs. Typically, state law enforcement organizations serve rural areas and stretches of highway.

Federal law enforcement consists of many different organizations, ranging from the U.S. Border Patrol to the Federal Bureau of Investigation (FBI). These organizations investigate certain federal crimes, which are specifically delegated to the federal sphere, or crimes that crossed state borders. When crimes cross state borders the federal government often investigates to avoid states’ arguing with each other over jurisdiction. Federal crimes usually include major crimes like drug trafficking, organized crime, terrorism, kidnapping, and hate crimes. Crimes committed over the Internet, such as hacking or fraud, are also considered federal crimes because the criminal and the victim are often located in different states.

The judicial branch tries and sentences those accused of a crime. After law enforcement apprehends a suspect, the suspect is tried in a court of law. The suspect is then known as a “defendant” and has the right to an attorney and a trial by a jury of his or her peers. If a jury reaches a unanimous verdict of guilty, with guilt being found beyond a reasonable doubt, the defendant is given a criminal sentence. The sentence may be determined by a judge or jury.

After sentencing a convicted defendant is placed in the corrections system, be it probation or prison. While defendants awaiting trial may be held in county jails, prisons are institutions, usually much larger, that house convicted defendants for sentences of one year or longer. All 50 states and the federal government have their own prison systems, which must treat prisoners according to the laws laid out by their respective legislatures.