There are a variety of law enforcement agencies in the United States, and they come under the jurisdiction of many different authorities at federal, state, county, and municipal levels of government. The U.S. does not have a national police force, but there are a few federal law enforcement agenies, best known as the Federal Bureau of Investigation (FBI).1
The FBI is the principle investigative arm of the U.S. Department of Justice. The FBI gathers and reports facts, and compiles evidence in cases involving federal jurisdiction. The Drug Enforcement Administration (DEA) is also a part of the Department of Justice.1
The majority of the U.S. states have police departments, but most state police force activities are concentrated on high way patrol and other traffic work. County governments maintain police forces under the command of a sheriff.
The mission of the United States Department of Justice is as follows2:
To enforce the law and defend the interests of the United States according to the law; to ensure public safety against threats foreign and domestic; to provide federal leadership in preventing and controlling crime; to seek just punishment for those guilty of unlawful behavior; and to ensure fair and impartial administration of justice for all Americans.