(a) Except as provided by § 158.010, the commission shall adopt, publish, and enforce rules regarding:
(1) the definition of a county employee;
(2) selection and classification of county employees;
(3) competitive examinations;
(4) promotions, seniority, and tenure;
(5) layoffs and dismissals;
(6) disciplinary actions;
(7) grievance procedures; and
(8) other matters relating to the selection of county employees and the procedural and substantive rights, advancement, benefits, and working conditions of county employees.
(b) The commission may adopt or use as a guide any civil service law or rule of the United States, this state, or a political subdivision in this state to the extent that the law or rule promotes the purposes of this subchapter and serves the needs of the county.

(c) The commission may not adopt or enforce a rule requiring a county employee to retire because of age. The commission may adopt a rule requiring a county employee, on reaching an age set by the commission, to submit annually to the commission an affidavit from a physician stating that the employee is physically and mentally capable of continuing employment.