Michigan Compiled Laws, Chapter 51. Sheriffs § 51.357

Sec. 7. After the date this act takes effect, appointments to and promotions in sheriffs' departments subject to this act shall be made only according to qualifications and fitness to be ascertained by examinations, which shall be competitive, and no person shall be appointed, reinstated, promoted or discharged as a member of the department regardless of rank or position, in any manner or by any means other than those prescribed in this act. The positions of undersheriff and departmental heads are exempt from the operation of this act, and the sheriff shall have the sole power and authority to fill such positions.