The US Department of Justice exists to enforce the law and make sure there is punishment for those who are guilty of breaking it.
There’s a lot of incredibly interesting departments and areas inside the DoJ. These include the FBI, Tax Division, Civil Rights Division, Interpol, Drug Enforcement Agency and more.
The department describes its role as: “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.”