1. Bargaining unit standards. In the event of a dispute between the public employer and an employee or employees as to the appropriateness of a unit for purposes of collective bargaining or between the public employer and an employee or employees as to whether a supervisory or other position is included in the bargaining unit, the executive director or his designee shall make the determination, except that anyone excepted from the definition of public employee under section 962 may not be included in a bargaining unit. The executive director or his designee conducting unit determination proceedings shall have the power to administer oaths and to require by subpoena the attendance and testimony of witnesses, the production of books, records and other evidence relative or pertinent to the issues represented to them. In determining whether a supervisory position should be excluded from the proposed bargaining unit, the executive director or his designee shall consider, among other criteria, if the principal functions of the position are characterized by performing such management control duties as scheduling, assigning, overseeing and reviewing the work of subordinate employees, or performing such duties as are distinct and dissimilar from those performed by the employees supervised, or exercising judgment in adjusting grievances, applying other established personnel policies and procedures and in enforcing a collective bargaining agreement or establishing or participating in the establishment of performance standards for subordinate employees and taking corrective measures to implement those standards. Nothing in this chapter is intended to require the exclusion of principals, assistant principals, other supervisory employees from school system bargaining units which include teachers and nurses in supervisory positions.

2. Bargaining unit compatibility. The executive director of the board or his designee shall decide in each case whether, in order to insure to employees the fullest freedom in exercising the rights guaranteed by this chapter and in order to insure a clear and identifiable community of interest among employees concerned, the unit appropriate for purposes of collective bargaining shall be the public employer unit or any subdivision thereof. No unit shall include both professional and nonprofessional employees unless a majority of such professional employees vote for inclusion in such unit, except that teachers may be included in a unit consisting of other certificated employees.

3. Unit clarification. Where there is a certified or currently recognized bargaining representative and where the circumstances surrounding the formation of an existing bargaining unit are alleged to have changed sufficiently to warrant modification in the composition of that bargaining unit, any public employer or any recognized or certified bargaining agent may file a petition for a unit clarification provided that the parties are unable to agree on appropriate modifications and there is no question concerning representation.

4. Unit merger; same bargaining agent. If there is the same certified or currently recognized bargaining representative of public employees in multiple bargaining units with the same public employer, the public employer or certified or recognized bargaining representative may file a petition with the executive director to merge those bargaining units. Upon the finding of the executive director or the director’s designee that the expanded unit would conform with the requirements set forth in this subsection, the executive director shall order an election within each bargaining unit to determine whether a majority of the employees voting in each bargaining unit wish to be within the expanded unit. The only question on the ballot in a merger election is approval or disapproval of the proposed merger. The executive director or the director’s designee shall certify the bargaining agent for an expanded unit consisting of any bargaining units in which a majority of the employees voting approved the merger.