Under section 17 of the Police Act, 1861, the purpose of appointing Special Police Officers is to:

Section 17 permits appointments when the ordinary force is insufficient for "the protection of the inhabitants and the security of property" during the specified disturbance. The appointment supplements the force for that situation. Section 18 gives special officers ordinary police powers and duties; their purpose here is not permanent replacement of the regular investigative force or exercising judicial trial powers.