In 1866, a supplement to the act was passed extending the privilege to "embrace all corporations, firms, or individuals, owning, leasing, or being in possession of any colliery, furnace, or rolling mill within this commonwealth". The 1866 supplement also stipulated that the words "coal and iron police" appear on their badges. A total of over 7,632 commissions were given for the Coal and Iron Police.
In 1866, a law was passed to regulate the coal and iron industries in the state by granting authority to individuals or organizations who owned, leased, or operated mines, furnaces, or rolling mills. This law mandated that "coal and iron police" be displayed on their badges. A total of over 7,632 commissions were issued for these officers.