Estimates from the Bureau of Justice Statistics show that there are approximately 18,000 state and local law enforcement agencies in the United States. Two-thirds of these are local agencies. Local law enforcement agencies derive authority from a local governing body such as a municipal or county government. The bare minimum educational requirement to work as a local law enforcement agent is a high school diploma, and certification from a police academy. Local police, special jurisdiction police, detectives, sheriffs and deputy sheriffs constitute officers who facilitate law enforcement in the local government.
Police agencies usually designate their police officers to patrol a certain area within their jurisdiction to ensure proper law enforcement. Patrol officers dress in uniforms to allow the public to identify them. In the course of their patrols they look out for any criminal activity. Patrol officers have the authority to apprehend and arrest suspected criminals and conduct searches on persons or premises that they reasonably suspect to have an involvement in criminal affairs. During patrols, the officers respond to emergency calls and offer any necessary assistance such as first aid.
Local police officers are in charge of investigating any complaints received in their respective agencies. The investigation procedure includes interrogating suspects and witnesses; collecting evidence on an accident or crime scene; conducting surveillance of suspects; examining relevant documents; conducting raids; and arresting suspects. After arresting suspects, the officer in charge writes reports and files the required paperwork. He might have to appear in court as a witness for the case. Many local detectives operate as plainclothes officers and usually concentrate on a specific type of case until they solve it.
Local police agencies organize and oversee community policing programs aimed at creating a link between the public and police agencies. This allows them to work together to prevent criminal activities. An example is the Neighborhood Watch program, which advises residents on how to keep an eye out for suspicious activity and report it to the police. City agencies usually promote such programs to the public and educate citizens about crime and the law.
In some cases police personnel are responsible for enforcing laws in particular areas. For example, sheriffs and their deputies oversee county law enforcement duties not covered by municipal police forces. They run county jails, serve court summons, and may work in local courts as security officers. Public colleges and universities usually have police officers who maintain law and order in the institution. Transit and railroad police provide protection for passengers and workers in transit stations and railroads.