Private police or special police are types of law enforcement agencies owned and/or controlled by non-government entities. Additionally, the term can refer to an off-duty police officer while working for a private entity, providing security, or otherwise performing law enforcement-related services. Officers engaging in private police work have the power to enforce the law. However, the specific authority they have, and the terms used for it, vary from one place to another.
In jurisdictions that allow private police, private police may be employed and paid for by a non-governmental agency, such as a railroads, ports, campuses, nuclear facilities, and hospitals and other "special police" but they are peace officers or law enforcement officers who are commissioned, licensed, and regulated by the state. They are required to swear an oath to uphold the laws of the state where they are commissioned and follow the same regulations peace officers / law enforcement officers must abide by. The main difference between a private police officer and a regular police officer is who is signing their paycheck and their jurisdiction.
Many people confuse private police with security guards, which is separate or arguably a subset. Security officers are regulated by the state, but generally do not have police powers, such as the ability to arrest on a warrant, or issue citations and summons for misdemeanor offenses. In contrast, most private police are sworn police officers employed by private entities, or even small governmental departments (such as library police, etc.).
Even though private police departments receive their commissions from the state (or counties, municipalities, etc.), they are generally not considered government actors.
Private military companies providing law enforcement services may be referred to as private gendarmeries or private civil guards, due to their more militarized nature.