Idaho Code § 50-1521

No paid policeman shall be retired under section 50-1514[, Idaho Code,] prior to January 1, 1950, unless he shall be discharged from service because of his incapacity in a degree which prohibits efficient service as defined in subdivision (h) of section 50-1502[, Idaho Code]. The provisions of sections 50-1501 through 50-1524[, Idaho Code,] shall apply only to persons now employed or hereafter to be employed as paid policemen.