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 amended to grant authority to all corporations, firms, or individuals who owned, leased, or operated coal mines, furnaces, or rolling mills within the state. This amendment also required that "coal and iron police" be displayed on their badges. A total of over 7,632 commissions were issued for these officers.