As used in this act the following terms shall have the following meanings:
(1) “Firefighter” shall mean the paid members, except supervisors, of any regularly constituted fire department in any city, county, fire district or political subdivision within the state. The term “supervisor” means any individual having authority in the interest of an employer to hire, direct, assign, promote, reward, transfer, lay off, recall, suspend, discipline, or discharge other employees, or to adjust their grievances, or to effectively recommend such action if in connection with the foregoing the exercise of such authority is not merely routine or clerical in nature but calls for the consistent exercise of independent judgment; provided, the term “supervisor” shall include only those individuals who perform a preponderance of the above specified acts of authority on a day-to-day basis; and provided further, a supervisor’s administrative responsibilities must include demonstrated involvement in policy and budget formulation for the department. Nothing herein shall prohibit any individual employed as a supervisor from becoming or remaining a member of a labor organization, but no employer subject to this act shall be compelled to deem individuals defined herein as supervisors as employees for the purpose of any law, either state or local, related to collective bargaining.
(2) “Corporate authority” shall mean the council, commission, trustees, or any other governing body of any city, county, fire district or political subdivision whose duty it is to establish wages, working conditions, and other conditions of employment of firefighters.