A police department may be the branch of presidency concerned with enforcement of law and prevention of crime. The definition of police department means the central organization that takes good care of the functioning of various sub agencies under it. Within a vast and extensive country such as the US, each state carries a separate police department that can proper care of maintaining the law and order. The authorities department plays a pivotal role within the smooth functioning with the law and order machinery within the respective state. The usa of America carries a amount of the police that function towards preserving peace and security.