GOV §3599.75: (a) In determining an appropriate unit, the board is governed by the criteria in subdivision (b).

(a) In determining an appropriate unit, the board is governed by the criteria in subdivision (b). However, the board shall not direct an election in a unit unless one or more of the employee organizations involved in the proceeding seeks or agrees to an election in the unit. (b) In determining an appropriate unit, the board shall take into consideration all of the following criteria: (1) The internal and occupational community of interest among the employees, including, but not limited to, all of the following: (A) The extent to which they perform functionally related services or work toward established common goals. (B) The history of employee representation in state government and in similar employment. (C) The extent to which the employees have common skills, working conditions, job duties, or similar educational or training requirements. (2) The effect that the projected unit will have on the meet and confer relationships, emphasizing the availability and authority of the employer’s representatives to deal effectively with employee organizations representing the unit, and taking into account such factors as work location, the numerical size of the unit, the relationship of the unit to organizational patterns of the employer, and the effect on the existing classification structure or existing classification schematic of dividing a single class or single classification schematic among two or more units. (3) The effect of the proposed unit on efficient operations of the employer and the compatibility of the unit with the responsibility of the employer and its employees to serve the public. (4) The number of employees and classifications in a proposed unit and its effect on the operations of the employer, on the objectives of providing the employees the right to effective representation, and on the meet and confer relationship. (5) The impact on the meet and confer relationship created by fragmentation of employees or any proliferation of units among employees. (c) Political affiliation shall not constitute a community of interest for purposes of determining an appropriate unit.